Rosco's paint tips

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rosco
Posts: 2569
Joined: Wed Feb 04, 2004 8:34 pm
State: VIC
Location: Melbourne

Rosco's paint tips

Post by rosco »

Hi Cam,
this gives us a bit of "space" where we won't bother those who do not want to follow what you are doing regarding panels.

I suppose we must start with a basic outline.........

My basic procedure goes like this - this is for acrylic only - my enamel procedure is a little different..............although preparation is identical..

Degreasing, drying. - We need to discuss a fair bit here - there are pitfalls which most people fall for the first couple of times around........silicone is one of those which is often overlooked - now is the time to chemically strip any silcone waxes from your work - before you go grinding it further into the existing paintwork................we do this with a wax and grease remover - before any sanding or abrasion takes place!

Scraping, grinding, filing, brushing and sanding back.
A bit like erecting something - we need to establish a sound foundation from which to start from...

Grinding out or treating rusted areas.
If one thing is going to prematurely destroy your work - it will be rust.
Lots to talk about here.....

Welding in new sections too large or where filler is not suitable.
I remember you saying you cannot weld - sometimes it is better to get someone to weld in a piece rather then just try and fabricate using filler - or "bog" as it is known.....

Beating out dents.
If you can, get a cheap set of hammers and dollies - they don't need to be more than around 20-30 dollars - you will use them forever......
It is often much better to get some of the deep dents out rather than just filling and filling with bog - you will find in an accident that bog will break open very quickly - and reveal to the world where you have used it to fill big holes.......

Heavy sanding using very coarse paper/discs.
We need to create a substrate which is going "key" subsequent coats.

Thoroughly blow out all dust/filings.
We don't want stuff in cavities crevices to make an appearance later on when you come to laying down those precious top colour coats....

De-oxidine to exposed metal.
You MUST do this - it will neutralise any microscopic spots of surface rust - this process starts almost immediately metal is exposed to air - especially when humid........

Filling using a re-enforced filler.
This is used to fill larger gaps, dents, holes - it has fibre=glass or stainless particles in it which "hold" the filler together. It does have limits though, refer to welding above.......
To apply this stuff, you must mix it up exactly according to the instructions - don't be "tempted" to make it go off quicker by adding more hardener.
Only mix up enough which can be used in three minutes - again it will "go off - or gel" in warmer/drier conditions.
We use a plastic "card" to apply this stuff - you will learn to "scrape" it along the panel filling the voids as you pass.
You will need some acetone for cleaning up the mixing cup and "card" - not to mention your hands......... try to "clean up" before the stuff goes hard.

Sanding back.
You use a fairly coarse type of paper/disc here - it is pretty hard stuff to sand.
Getting a basic "shape" of how the panel should look, still with sanding scratches and tiny imperfections.

Filling using a fine filler.
This stuff is worth its weight in gold - in fact the stuff I use is in fact call "K & H Gold filler" very easy to sand and very, very fine - gives a very smooth finish when sanded.
Again, use your "card" or applicator. Acetone is again the stuff for clean up.

Sanding back.
This is where we actually start to "block back".
We use a very firm pad - one which will not crush, but just flexible enough to follow any contour.
of fine filler to obtain desired shape without voids.
This process is repeated a number of times rather than plastering the stuff on - if you plaster - you are both wasting material and time.
It can be applied quite successfully over itself, providing you wipe down with prepsol or a wax/grease remover and allow it to dry.


De-oxidine to surrounding exposed metal.

I am going to race ahead and put a bit into the next section - it is probably the bit most people have trouble with - it probably needs to be re-iterated that the most important part though is and always will be preparation of the panel prior to this...............

Spray procedure outline..............this is just an outline - although will probably be quite lengthy......and some of it will be quite detailed......
I could probably write a book on what I have leaned - both good and bad..

I do not spray below 18 deg or above 30
You run the risk of trapping thinners in the paint at cooler temperatures.
Flash off time must be lengthened accordingly.
If it is too hot, your paint will "air dry" as it makes way to the panel and results in the paint "sticking onto" the panel and not dissolving into the previous. In extreme cases you will see a sandpaper or heavily dusted appearance - do NOT try to correct this by applying futher wet coats.
Allow it to dry fully then block back - yo will only do this a few times before you "learn" not to spray "dry".......
If you must spray on a hot dry day - you can add a percentage of "retarder" into your paint mix - but you must also reduce the amount of normal thinners and end up with the same thinner/paint ratio.
On cooler days, of if you want a super gloss hard finish - you can opt for a "hot" thinner - be warned, this will penetrate "deep" into existing paint and may cause issues with fillers underneath - identified by "wet" looking patchies in the overall finish........ arggghhhh, there's a lot here Cam, thinners and how to get the most from them.......
We will discuss later the advantages of using different thinners and changing mix ratios - at specific times...............but for now, stick with the recommended mix just get some general purpose acrylic thinners and learn what "you" are doing with "it".

Pick the "right" day for your spray job - you will probably spend weeks in preparing panels for paint - don't get gung ho just because you have a day off - I have been known to "take" a day off because there didn't appear to be a suitable window approaching.

I do not spray above 50% humidity - there is no problem with humidity below this - we don't want to "trap" humidity in the paint.

Consult your gun handbook or notes - it will state what recommended pressure to spray at - it may even give you a number of different setting for different paint types.
You must have a compressor capable of keeping up to the demand of the gun. You will not ever have too much, but if you do not have enough - all sorts of problems start to arise - your settings will alter as the pressure drops - I believe this to be more applicable with suction type guns......
Make absolutely sure you have a filter/dryer fitted to your air line - I use two, one on the compressor in the regulator and a final one just before the air line. You will probably appreciate that when air is compressed, it is heated - when it cools down it cools and attracts moisture - this moisture becomes water droplets which if they get into your airline will also get into your gun - and paint - I can't tell you how frustrating that is when you finally get a great finish only to have a trickle of water run down the wet paint and ruin it..................... arrggghhhhhh...........
If you can, buy an extra long length of air line - suspend it from a fairly high up point and have it run back to the drier on the compressor - whilst you are mixing up the next pot of paint, remember to "blow" down the compressor and drier.

I have designed and fitted a "shop" air line into my garage - it is comprised of about sixty feet of 3/4" copper pipe. It uses a flexible connection from the compressor and the entire length runs upwards around the inside of my garage. Finally it drops down to the second regulator/drier where my flexible air line is coupled - I have never had anything come out of this second drier...........just me, I'm afraid.
It is important to try and get any moisture out of your air line......
Drain your compressor frequently, always open the drain valve just slightly at the end of each day (or break) and let the reservoir "blow down" slowly - this helps get most of any crud, oil, water out of your system.
Always leave that drain open when not in use.

Back to spraying................
Normal distance from gun tip to panel is the span of you hand - approx 8 - 10 inches - I'm a dinosaur, you will have to convert that to cm.
Before you even get a gun, you can "play" with this just by passing you hand along an imaginary or existing panel - see if you can learn to make a pass keeping your hand exactly the same distance from the panel without "rolling your wrist" Try to imagine overlapping a previous pass by one third and whilst doing both of these, try to maintain a consistent speed.
You are going to have to actually spray some paint to learn what this speed will be.
I try to "look" at the wetness of the paint immediately behind the fan as it runs along the panel - that gives me the best indication of whether I am running fast/slow enough - too fast and the coat will be thin/dry - too slow and it will be "wet" and very likely to run..............you will learn to identify this, but not for some time...............if you now get a chance to see someone spray some paint - you will begin to "see" more than you previously were able to understand..............
When you "run" your gun along a panel, keep your distance and speed constant.
Try not to "roll" or "wave" your wrist as you go - that is don't "sweep" in an arc as you move along the panel - your coat will "build" at the closest point and be quite thin (possibly dry) at the start and end of any "wrist" stroke.
Try to keep the gun pointed at right angles to the panel - that is, don't allow the gun to point anywhere but at the centre of the line where you want to spray.

Learn to "trigger" the stroke - start your pass by starting a foot or so before the panel, get your speed constant then pull back the trigger before you reach the panel sp that the fan gets setup.
Continue all the way beyond the panel before releasing the tricker.
You do not want to have the gun start to reach it's settings after you reach the panel - always just prior.
Continue your run just beyond the panel end so that the settings to not start to break down as you reach the end.

Try to overlap each pass along the panel by one third - a good quality gun will be designed and machined to provide a slightly thicker film in the centre section of each pass - this allows previous and following passes to obtain an overall flat application...........
There is much more - you will start to ask questions once you have had a play with this............. but for now - it will give you an outline of laying paint down.

We will need to discuss spraying curves (both concave and convex) how to "plan" how you are going to make your passes (this is important for panels such as roof and how to shoot a whole vehicle at once).

I will later reveal my tips for tricky spots, crowns and working within recesses/door "shuts" and spraying "overhead" from beneath.

I must include a "faults and fixes" page which you may wish to keep handy.

that's enough background ........... for now...

One thing on gravity guns Cam, if you forget to connect the air line, have not opened up the gun air control valve and pull back the trigger - paint will run out in a stream................... I've done it... I bet others have too!

So hopefully some of that will have found a "home" and you may feel you are ready to begin...........

It is now time to get out that new face mask, fit the filters and get used to wearing it when you spray.......... if you are contributing to superannuation, this is the bit which may help you retrieve some of it........
When ever you can "smell" paint whilst wearing the mask - it is time for new filters. With some of them - mine is a CIG or now known as BOC gases, you can get pre-filters which a just little thin paper pieces - they help prevent paint dust getting in and blocking your main filter - they will extend the life of main filters for quite some time.
Change these pre-filters after each session.........

Now to spraying.......

Always find something to "practice" on before you actually hit a panel.
It doesn't have to be anything special - I use an old fridge door......... there is that much paint on it now I could probably remove the metal and still fit it to the fridge..........
We need to get your paint, gun and pressure set as best we can before applying it to your panel.
What we want is to be able to make a pass and get a good even coat with a nice slightly wet fan.
Distance is going to be very important - when you get your needle, fan, pressure and speed ready, you must apply exactly the same technique to the panel.........makes sense......
Spray a quick burst at the panel from 8 - 10 inches. Have a look at what the paint looks like. If it is split, you have too much fan or too much pressure. Likewise, if it is centred or round, you have too little.
When you get a fan of the correct height and roughly even spread, run another one but this time along the test piece - you need to find out how fast/slow to make a pass.
You are looking for a nice slightly wet result of consistent height.
Too fast and it will be dry and thin, too slow and it will probably run - or remain wet looking for five or more minutes.
Our pass is going to start to visibly dry in about two to four minutes.
I suppose many people here will use a different style, I can only speak of what I do...........
Run another pass which overlaps your first - you are looking for the two to look as one large pass. This is going to give you how much to overlap.
When you start to get a feel for each of your guns, you will have enough experience with each one to know how much to overlap.
General rule is by one third............
Ready to spray the panel?

We start with 1k etch - this stuff is important - it etches into metal and provides a sound base onto which primer will "stick".
Some people go straight for the primer - don't, the etch is a great way of keeping your finish attached to the panel......

Spray ONE! medium coat of 1K etch primer - this is generally pre-mixed but make sure you "stir" the contents - the particles will settle in the bottom. Don't be tempted to try and "cover" with this - it is a translucent coating - you should be able to "see" everything under it.

If your coat is too thin, fast or pressure too high, you may find (spider web) starts to grow outside your spray area. This is because the etch is drying prior to reaching the surface. You can either drop back pressure slightly (although with a suction gun this will probably reduce the amount of "draw" up the pipe), open up the needle a bit or slow your pass down...........
You will know if you are too heavy, slow, or have the needle opened too far - it will run........... leave it, block it back - these words are going to "haunt" you forever Cam................

Initially your challenge is to find the combination where everything is set in unison (pressure, fan, needle, distance and speed) you will then be able to run a good moderate wet coat without runs................

note:- I do find that the 1K etch sprays a bit different to that of primer and top coats............

Mix up your primer/surfacer according to the data sheet for the product
- I use the old Dolmio, Aloro or Kan-ton glass jars - these have measures both in mls and ozs - try to learn to work with one not both.
I find these glass jars are great. I hope you can still get them.......don't think much of the food - we had to consume quite a bit, but it was a sacrifice I was prepared for my family to make............

Mix up enough paint to do the job - initially you are going to waste a bit - you'll get a feel for how much you'll need as you get into this.
I have a little trick which helps me determine just how the paint is going to "spray" - I shake the mix for twenty/thirty seconds or so in the glass jar and quickly place it on the bench - I count out in seconds how long it takes to see the bubbles appear - it is a guide - with most paints I spray it takes around 4 seconds - by my counting.
If it doesn't take that long - the paint is thin or the temperature is high.
If it takes longer - it is either thick or cooler - both these indications will have a bearing on how I will adjust my gun and run my passes............
You'll learn all of this as you go............. but most of it will only come when you actually start to spray.............speaking of which.....

Spray two/three coats of primer/surfacer and let it dry for a few days.
Block back using blocking pad and wet/dry papers working up from around 240 through to 400.
I want to walk you through blocking back, but not yet........ there are a number of tricks I have learned which may save you a lot of grief......
If you now see great spots which require quite some build - you are better off re-applying some fine filler and blocking back, rather than keep filling with primer - filler will not shrink in time - primer will to some extent.
But be warned - if you use a "hot" thinner later on - this will make any filled spots look "wet" and will cause different drying times in localised areas........ we'll get to this...........

Repeating primer/surfacers and blocking back until satisfied with preparation that is when you believe the surface is flat or follows the contour of your panel without "high or low" spots.

Final top coats of primer.
These ones are probably going to be blocked back - it's just an additional layer so that the following "guide coat" can be removed with.......

Spray mist coat of sub-frame black (guide coat) - keep this coat just barely visible- your are going to remove it all, it is only to provide a view of any problems prior to starting colour coats..

Block back to "find" low areas (remain black whilst sanding)
Build up again with primer as required by guide coat indications.
If you want that almost perfect panel, you repeat and repeat this until it only takes two/three light rubs to remove "guide coat".
When you have reached this stage your preparation is ready for colour coats - we do not "build" our surface with colour coats - the primer/surfacer should have done this for you.
Colour coats are for decoration and sealing of the primers......
I am going to confuse you if I go into this........... let's just say - colour coats are the "finish"...... primers will not seal and will permit moisture to penetrate - this is called hygroscopic - absorb water (I think this is whee your whole question originally started.... whether to go with Matt or Gloss.......?).

Some people only put down a few colour coats - I like to go a bit overboard and get a very sound sealing coverage in about three separate applications.
Every time you cut (and I hate the word "polish") you must remove some of the paint. Paint will deteriorate if left unprotected - to keep a finish looking fresh you must wax it. When it breaks down only the outer layer need be removed. This is done with an abrasive "cutter" and you will "see" the colour of your paint on the rags - it is thus logical that eventually you will run out of paint film............. so, I like to put that little extra on to begin with..........
I also run an extra pass over "crowns" and bits where people are likely to "touch" - I have an abhorent hatred for people touching my paintwork - most enthusiasts will never "feel" another person's vehicle - if you "must" then please ask permission - I will gently wipe away any dust/grit with a soft towel preferably by first spraying some "detailer" over it to lubricate the film........aarrggghhhhh those fine finish scratches can be so hard to remove..........

I know this is going to sound as if my vehicle is a show piece Cam - it's not! - but I am ever so proud of what I have done, with the little "training" I have been given.......... hopefully you will appreciate some of this in time...

My colour coats go like this.......

First 2-3 colour coats. Allow to fully dry - 2 - 3 days.
Block back colour coats with 600 wet until fully "flat" appearance.
We will need to talk about what we are aiming for, but again not here.
(Stop blocking back if primer appears - this indicates insufficent "work" using primer. Color coat is purely for finish - not building).

Further 2-3 colour coats.
Let dry and block back as previous.

Inspection for final coats - again we need to discuss this.....

Final 2-3 colour coats.

Leave for sufficient time for thinners to fully evaporate and film to flatten down - this may take weeks - I have panels which did not fully flatten for months - but only in an attempt to get a "plate glass" finish.
Tell you how to do that, but not probably for some time

This next bit is how we are going to get a nice gloss to your work.......

Begin compounding with a coarse cutting compound. I do this by hand but most will use an orbital buffer and pad...... I can't help you with this.
We need to discuss when to move up to finer cutters..........not now..

Move to finer cutting compounds until level of gloss is obtained.
Leave a few weeks before again compounding with fine cutting compound.

The reason I do this is to allow any trapped thinners to escape and further flatten down the paint.

You must allow sufficient "time" for thinners to "flash off" or escape between each coat whilst spraying - you risk trapping thinners under over lying coats if you don't.

The data sheet you receive with your paint (make sure you ask for it Cam - you can even get it prior to purchasing any from your chosen supplier)
This sheet will state what flash off is required between coats - it will only mention one specific temperature/humidity - if it is colder or more humid - it will take longer..............

Only after a couple of months should waxes or silicone sealants be applied...............
I do not like silicone - but it does provide lasting protection.
Silicone used on existing panels which are prepared can cause lots of trouble - if the get embedded into the paint, you will get "fish eyes" or crazy circles in your finish.......... I have learned to "hate" silicone around paint......
You can get an additive to mix in with your paint - it is supposed to "capture" any silicone - I have never used it. I find it easier to just keep away from the stuff..

Now for the between coat stuff - make sure everything is dust free - including you!
Wipe down with prepsol or a wax/grease remover - do not allow this to "dry" on the paint/surface - only wipe down as much as you can wipe off with dry, clean cloths at a time..............
Blow the surface to remove dust lint etc.
Try very hard not to disturb anything in your garage which will cause dust to get into the air............ I usually "spread" a bucket of water over the floor just before spraying - this is just me, Cam.............
Gently wipe over the surface with a "tack" rag - keep this in a sealed container. It will usually pick up all those little microscopic bits of dust you will find annoy the living daylights out of you when inspecting a finish.
Finally, don't be "tempted" to run you fingers/hand over paint until it is dry - it may look great/dry whatever, but you will find it is still soft and touching it may break its composition.............

So Cam, these are the basic steps - others will undoubtedly suggest different methods of performing each stage......... this is what I do, and it works for me - I can't say that it will for you but it is a start..........

There are quite a few additional "notes" and techniques I perform and will explain during each of the above...............

That should give you another five or ten minutes material to digest..........

looking forward to questions.

I have only every uploaded one pic onto this site - I may look at posting a few more which hopefully will aid to the explain some of the above..............

I would suggest you purchase a breathing mask prior to spraying - the one I use has replaceable filters - make sure you purchase the filters recommended for automotive spray painting.
Just looking at the above - we've got to seven pages already - there is probably enough for a book here................you may wish to save this in a folder somewhere............
I'd like to talk on spray guns a bit before you go out and purchase one.....
but that's enough for now.............

frats,
Rosco

ps I'm going out to the garage to take a pic of my guns..........
I'll try and have it up this evening - with a brief discrption and what I use each one for..............
Last edited by rosco on Fri Apr 11, 2008 7:42 pm, edited 6 times in total.
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Devilrod
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Post by Devilrod »

Wow!!! 8) 8) 8)

Rosco, I don't think I've typed that much in all my posts. :lol: :lol:

This is one of the reasons though why I like this forum. Great information and probably one of the most helpful tools in building a car....
Speed and Style........... One day I'll get the speed bit.
Mephious
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Post by Mephious »

Nice post rosco !
MINT62
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Post by MINT62 »

geez rosco :shock:

thats an amazing effort, well done
that would of taken me 1/2 a day to type :lol:
you should write a novel, what am i saying :roll: - you just did
thats gotta be a record, talk about dedication to a cause :wink:

cheers ray
camstuart52
Posts: 221
Joined: Tue Oct 02, 2007 10:35 am
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Location: Hobart, TAS

Post by camstuart52 »

I am unable to show you the level of appreciation that the information you are providing deserves through the internet!!! If i cant do this with that sort of knowledge and help, then i dont deserve the car!!! :)

I must say that I'm looking forward to getting started on this...........quite excited!!!

Your post lengths make mine feel like a poor excuse of a reply!!!

Someone give this man a medal!!! :wink:
rosco
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Joined: Wed Feb 04, 2004 8:34 pm
State: VIC
Location: Melbourne

pix

Post by rosco »

As promised,

here are a few pix together with a bit of a "brief" on each......

The first is a group shot of all my guns -
Image

My "history" in spray painting.............. this is the bit you aren't going to have to learn by experience.......... I've done it for you.......... just read and be entertained..........

The very first time I ever sprayed paint onto my vehicle was using a very clever little system called Preval.
This was in 1974 after a chap backed his brand new XC panel van into the right rear of my old bus........... I wasn't happy, Jan!
Insurance companies were impossible - I think you may appreciate at the time that an EK Holden was 13 years old - it didn't take much damage for them to be considered "write-offs" - mine wasn't quite that bad, but the insurance companies weren't prepared to give new for old repairs.........
I spent many very worried nights over the damage until I decided to try and do my own repairs........... the chap came to the party and paid for all materials and a little towards some of the equiment....we parted on good terms......

I "found" this Preval system in Holden's Ringwood paint shop - pleading poor and showing them the vehicle - all were very disappointed that it had been "damaged" it was truly in magnificent condition - tell that to Insurance companies.............. never forgave them... life's learning curve, eh?
They put me onto the Preval system knowing I didn't have a hope of buying a compressor, gun and all the associated needs........ but I think I owe them a great deal in the beginning of my spraying experience.......I drove them nuts, I can still see their faces after about the twentieth visit with yet another question - I think they would have done the job for me if they knew what a persistent customer I was to become.........

The paint colour of my car was not available in aerosol "touch up" cans.....
and it was before the time when you could get a supplier to "mix" up an aerosol for you.......so hence the little magic Preval system (it is still available today.....).

With this system, it came with three 6 oz bottles and a power unit (aerosol tube with plastic spray button) I thought this was marvelous - what I was to find out was that it was very restrictive and you had to always have a few "spare" power units........... but yes, I could spray..........

Some time later, I got into radio controlled aeroplanes and purchased a Badger 200 air brush (pictured - blue) - Cam, you can't appreciate how much time I spent playing with that little unit - I soon grew tired of purchasing aerosol cans of "air" and found I could get a "spare tyre" adaptor. I drove the local garage nuts with my regular trips to his tyre hose and re-filling as many spare wheels that I could fit into my boot.......I sprayed the entire vent intake in front of the window with that air-brush - it too is still untouched - can you imagine how long that took.................?
Spraying in 1/8th inch runs..........

Next, after I sprayed up a model locomotive for a work colleague, he "gave" me a very crude home made compressor.......... it consisted of a Villiers four stroke engine modified with a 1/2" plate head into which were two Holden fuel pump check valves - from there it was connected to a gas bottle as a reservoir. It had an adjustable safety valve which controlled pressure. Basically, the thing worked all the time, the safety valve blew off any excess - I had a ball with that using the air brush.......I had to replace the check valves regularly - they weren't meant for the high temperature of compressed air - I knew when one was spent............ the pump would give a number of odd beats whilst the valve was trying to seat and then come good for a while............ risky buisness when it came to spraying acrylic paint...........

My horizon then grew a little further when I found the next gun - I believed the crude compressor had an output of approximately 3 cfm...........in good condition - not much, but enough to step up to the smallest of touch up guns - you will see that at the very left of the above pic.

I removed and sprayed my boot (not footware, silly) using this system - it gave a reasonable result, except that the gun would "flutter" without warning - I later found this out to be related to lack of volume - we will discuss this in another post........

My bootlid to this day is still as sprayed back in around 1988......... I can show you every defect, but most will have to be "told".......

In 1992 I finally got enough coupons together to purchase the air compressor below -
Image

I did a lot of research and beleived this to be best value for money at the time - really, it is a great unit.
I made some modifications (lengthened the air line from the tank to regulator, fitted regulator/drier, and fitted a sports paper element type air cleaner - I have never felt the little foam ones do much except stop rocks)
Once I had the air, that touch up gun just didn't improve my results.

I then moved on to the large red gravity spray gun - below

Image

I was told it was HVLP - High Volume/Low Pressure - meaning high volume paint output at low air pressure -which it is - but wasn't told it still required a lot of air volume - the compressor worked almost continuously keeping up with this unit - it has numerable "fan" holes all which consume a lot of air volume......
I played with this for quite some time and it was here that I learned a bit about needles and tip sizes - the one in this is a 1.2 mm - too small to spray primer - great for pearlescent/metallic and clear coats - but not for what I wanted.
I persevered with it, but just couldn't get top coat to flow "wet" without thinning it right down to the point you could almost see through it.......

I saved up and finally purchased the Iwata W 77 - below.

Image

haven't looked back - this gun is magnificent - it is probably a tradie's gun........... from day one - it just blasted paint onto anything I took it to with a great fan, excellent coverage and a "feel" in adjustment which was starting to make sense.......

To do my door shuts, I bought a gravity touch up gun third from left - it is called a Hi-Tech 826 - below - it has a tip/needle of 0.8 mm-

Image

- Cam, I can't tell you how I love that little gun - I use it without any hesitation for any job............ I'd be lost without it.

For intricate stuff I use the little blue Badger 200 airbrush.....

For touch ups and engine bay components and the bay itself - I used the Hi-Tech touch up.

For large panels and items requiring a full even cover - the Iwata.....

That now leaves us to the final gun in the picture- the centre gravity one below-

Image

it is an Air Gunsa - made in Italy under license from Iwata - If I were to only have one gun - this would be it. It has a 1.5 mm needle/tip .......... it can come down to around 1 1/2 inch fans and open up to nearly six.............. it has fan control, air control and of course - paint control - all on the gun...............
The quality of that gun is exceptional - just like the Iwata.............

So, Cam - you are going to ask me - my favorite - still the little Hi-Tech gravity touch up.

My suggestion to you.......... I don't know.... sorry, as we mentioned previously, you are going to be the one who must get comfortable with what you decide on......I am more comfortable with the big Iwata suction gun for spraying large volumes........ I just don't have confidence in using the big gravity gun.
Others reading this will suggest my changing the needle and tip to a larger 2.0 - yes I could do this, but having the 2.0 mm in the Iwata really makes this a bit unjustified. I prefer to keep each gun intact and not change components.......
I will get another large gravity gun later, but with a 2.0 mm tip and needle set............ it will be used for etch and primer only.

Before you even think about purchasing a compressor - you have to do a bit of research - you must get the minimum sized compressor for the maximum sized jobs you are going to do - air tools - grinders/ snaders/ rotary machines use a lot of air............. they are hungry little beasts.
Your compressor will be the life-line of any spray painting you do - you NEED enough air.
Don't be fooled by some of the manufacturer's quoted capacities - you need to know how many CFM (cubic feet per minute) the unit is capable of and at what pressure - most should state 100 psi....
I hear a lot of people speak of litres - sometimes this just relates to the size of the fitted tank - that in no way gives any indication of what the pump part of the compressor can supply............ I think we need to discuss this prior to you making any choice.......... I have a set of times which relate to "true" CFM - we need for you to understand this a bit more to get a unit which will not become an achilles heal.......

That's enough for now......
You are going to have some more questions from this, I hope..........

frats,
Rosco
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Devilrod
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Post by Devilrod »

I have been told by the guy who painted my roof (ex beater sprayer), 2 pak 1.2 - 1.4 and for Acrylic colours, clears 1.8, Acrylic Primer/putty 2.0 and metal flake 2.0 or bigger.

I know we used 1.4 for the white (borrowed gun) and the roof not done by me but by Craig had a way better finish due to nozzle size according to him. He has seen how we paint and can't fault that, just what we used :oops: :lol: :lol: :lol:
Speed and Style........... One day I'll get the speed bit.
rosco
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nozzles

Post by rosco »

Thanks DR,
I need input............ I can only relate to what I have found - as mentioned I have absolutely zilch experience in 2K, metal flake/ pearlescents/ clears.
One day will have to learn it - maybe by choice.....
Thanks again DR - will add this to my notes......
frats,
Rosco
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Devilrod
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Re: nozzles

Post by Devilrod »

rosco wrote:Thanks DR,
I need input............ I can only relate to what I have found - as mentioned I have absolutely zilch experience in 2K, metal flake/ pearlescents/ clears.
One day will have to learn it - maybe by choice.....
Thanks again DR - will add this to my notes......
frats,
Rosco
Sometimes though if you are used to a certain setup it is hard to change.... whether right or wrong the end result could still be tha same.
Painting can be funny like that. It might mean more work for the same finish :?
Speed and Style........... One day I'll get the speed bit.
Oldnblue
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Post by Oldnblue »

Hey Rosco et al.
Any chance this post par excellence can be added to the Tech Archive when it's 'finished'.
It's too good to let slip away.
Great stuff.
Cheers, Scott
camstuart52
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Post by camstuart52 »

When buying a compressor - what CFM (cubic feet per minute) would be recommended for this sort of application. Like you say, I dont want to be under resourced, and I dont really want to have to buy twice!!! I`m getting into building shortly and i`m going to need a compressor anyways, so this is a good excuse i can use......hahahahahaha

Guns it appears are quite a complicated little item and really i have no idea what type to go for!!! Rosco (or anyone else) is there a particular gun that you would recommend, that is going to be the simplest and most forgiving........

I`m thinking I might start with an even smaller and more simple panel now!!! :lol:

Is going back to bare metal recommended??? Is it required??? Already I`m feeling a bit more confident thanks to all this info!!!

Now what is "blocking back"??? Its been said a lot and now I`m quite intrigued as to what it is!!! I thinking I`m starting to get my head around some of this!!!
captainbill
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Post by captainbill »

Hey cam i used a 15 cfm compressor for years and it wasnt too bad for painting but it was average for airtools.When purchasing a new one recently they recommended a 17 cfm.There was lots to choose from and were reasonbly priced,a little over a thousand bucks.You may like to look into one of those.
As far as guns go i have 18 assorted guns but my most used one is a china special.
All my resprayes are baremetal although its not law.The more paint you leave on is more potential for reactions or shrink back.If you dont baremetal,prime well.
Blocking back is a term for rubbing either orange peel or defects out of paint by using a block of some sort.They can be cork,rubber or even rounded for curves.
rosco
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compressor

Post by rosco »

Relax everyone - this is short..............sorry, no it's not (sic)
Compressor - if you can afford a 17 or 18 cfm - I wouldn't hesitate........ make sure it is single phase, ie can be plugged into an ordinary wall socket........ if you need more on this, please reply.
If you can use it for "work" purposes and can have Wayne Swan assist with your purchase - I wouldn't hesitate in getting an industrial quality unit....... but look after it.......

Ok - a few words on existing paintwork - it will probably be neglected to some extent................ if you want to be "absolutely sure" that there are no underlying problems which may not become obvious until you shoot that last magnificent coat of paint - you must strip back to metal...............

If you believe the existing paintwork is fine, does not have "chips" or little rust stains here and there, or does not have any "humidity" bubbles in it............you may very well get away with a brisk block back to flatten and key the surface.............
I must admit I like to stip back to shiny steel and "build" the surface............
It is time consuming but does guarantee you know the "history" of the panel.

But I re-iterate, make sure you wipe down the surface with a wax and grease remover PRIOR to hitting it with any abrasive - you will "grind" that silicone/wax or whatever deep into existing paintwork..................

There is another little issue here which many will not be aware of - somewhere in the FB series - I am told, the General changed paint systems from nitro-cellulose to acrylic - nitro cellulose has "issues" with acrylic - acrylic does not have "issues" with nitro cellulose - this is from my paint supplier - I can't tell you Cam, anything from experience as my old bus was sprayed in acrylic - yours however is an FB........... can you please tell me what the colour code is on you vehicle's identification plate (front l/hs firewall) - we need to know the number - if it starts with a "585 - something" it's acrylic.............

Blocking back - must have skated over that, did I.....?

As CB says, it is the process of rubbing back paint or a surface until any defects are removed - obviously, you can't block back beyond the metal base.

When you start spraying Cam, you will need to block back between sessions. This is done to "work" up the surface so that each session gives the finish a flatter and more "filled" finish. It is also to create "keying" - fine lined scratches for subsequent coats to "get a grip into".
Secondly, you will undoubtedly make some mistakes and this will require flattening the finish back to remove the defect..........

As mentioned, it is done by using some sort of pad and fitting an abrasive paper over it.
The pad can be one of many differing types and the amount of "flex" in these pads differs immensely - for flat panels I use an extremely hard pad - have been known to use steel plate to get an absolutely "plate" finish.
For curves I use a pad with just enough flex to "follow" the curve.
For small valleys - eg along the stone-tray recess, I used a short length of 1" wooden dowel.
The "pad" is the instrument which ultimately will determine how "true" your "blocking back" will turn out............
- I will in time post an article just on blocking back - I believe it will assist many in obtaining a prepared primed surface which will afford every opportunity of a very good final overall finish.......

The abrasive is determined by the material which has to be removed.

Generally for acrylic primers and colour coats we use between 400 grit and 800 grit "wet and dry" a special paper which can either be used "wet" - ie with water as a lubricant/cleaner.
or dry - read below for my thoughts on "dry paper".

Wet........
One mistake which many make is to "block back" between coats with fine wet and dry - 1000 or even 1200.
This does provide a very "shiny" surface to the primer but it DOES NOT provide sufficient "keying" for the first (and all subsequent) colour coats to bond to.
I have some areas where this was done in the belief of a very flat and "plate" finish - it did indeed, but also chipped away from the primer whenever bumped or knocked.............. DO NOT be tempted to get this finish in you primer...........


Dry - although you can use wet and dry paper - I prefer to get a roll of dri-lube (white/light grey) aluminium oxide paper for dry purposes - I have rolls of varying grits - from 30 through to 240.
I use this paper for rubbing down bare steel, blocking back fillers and also blocking right back existing paintwork which has definite signs of neglect.
It is relatively cheap and suits may other "around the home" applications....
Anything "automotive" usually has an associated price tag - Bunnings is a good supplier of both wet and dry and also this "roll" paper..............
There's a bit her to learn about "cross-hatching" which I would like you to apply when "hitting" your first go at rubbing something down......
We'll get more into this later, Cam......................

Guns - as CB mentions - you are the one who is going to have to get comfortable in using one - I can't tell you which to choose............
Go into a supplier, pick a number of them up and have a "play" as previously mentioned - you must realise that they will NOT have an airline attached - this will be quite heavy and cumbersome - I need to tell you about air lines - there's a few tips to be offered which will prevent a bit of "grief" when you start using a lot of air....................

The gun will feel a fair bit different when it is filled with paint, has the airline attached and is "ready to shoot".......

Probably what I would suggest Cam, is to "handle" each gun and see how the "sit"in your hand - the controls are fairly basic in each - there are only a few to learn, but as previously mentioned, you must "learn" how to set them up so that all settings are in unison for the paint you are going to spray..................

I wasn't going to give you a quarter of what I have already typed, but will close with this little bit..............

On good quality guns there are three main adjustable controls..............

1.
the needle - it determines the "amount" of PAINT which will be admitted into the atomising head - adjustment is done by turning the screw on the rear of the needle -the further out the needle is set, the more paint.

2.
the fan - it determines the width of fan - there will be a knob on the side of the gun with a symbol of an increasing arc - turning the knob in the direction of the larger "arc" will increase the amount of air to "spread" the fan.
Without any fan air, the gun will shoot a straight squirt of paint.
Full fan air may "split" the paint fan pattern and leave the centre section almost clear of paint.............. you'll learn this when you read my previous and start to play on an old "something".....

3.
Pressure delivery control
Not all guns have this. It is located underneath the gun handle - you don't need it, but by golly having one when you are just a bit high in pressure is a lot handier than going back to the regulator and adjusting pressure there.
Simply, it is a LOCAL control of air pressure into the gun - it affects both the "shoot" and "fan" pressures........

The point where the paint comes out is called the head - it has two "wings" fitted to it.
On the underside of these wings the will be two or more holes - they are what creates the "fan"........
In the centre of the head, there will be the "tip" hole - where the paint comes out.
Around this central hole the may be anywhere from none to seven each side small holes - these are "atomising" holes - they help to keep the paint "atomised" as it travels to the panel..................

The front end, and in particular the needle and tip, head and wings are a very finely machined instrument - you must treat this part of any gun with the UTMOST respect - in particular the needle and the "tip" seat which is screwed into the front of the gun underneath the "head"............
We'll talk more on this later, Cam - I want to fully cover cleaning, maintenance and care of spray guns.................

Again, I've posted much, much more than I had intended at this stage...........

In one final paragraph, I would like you to visit a sales outlet - ask to have a feel of different guns........... always give them the impression you are about to purchase - but don't......... I would like to think you will have a number of visits before finally deciding on one in particular.

For acrylic AND primer, I would probably suggest a 2.0 mm needle and tip - as DR mentioned, they are (and I find for my purposes and style) probably the most appropriate for your initial needs................

Panel size - almost all of your work is going to be in preparation - it does not take "long" to spray - the preparation, and setting everything up ready to go and cleaning up is what will take all the time.................

If you are going to get a "full size" gun - you will probably be advised to take on something of around at least the size of a panel.............
If you (and this is what I would suggest) are going to try to do a smallish repair - I would get a "touch up" gun - something capable of throttling down to a 2" run but capable of opening up to around 4" - these little units are worth their weight in gold........... don't go overboard on price - you need to try and get quality.........i think by looking at the pic of my "Hi Tech" touch up gravity gun, you may see many available models around.
This gun will never be a waste - whether you use it for small repairs or working within the engine bay (I did my entire bay with my unit) or doing the door frames/shuts dash etc............ this is the one which will be very well suited to it.
My touch up gun has an 0.8mm needle and tip - I know that appears a paradox to what we mentioned about 2.0 mm - be are using this "little" gun under scaled down circumstances............. hence the smaller needle/tip.......

That's enough, you're probably asleep by now...............

mail me for more........

sorry folk, I lied - how many pages did that "few lines" get to......?

frats,
Rosco
oldnek
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Post by oldnek »

Rosco, Your tech info is a must for the tech archive, heaps of valuable information there mate. Nice touch on the photos for all, to tell the difference in the spray guns as well.

Regards John
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camstuart52
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Post by camstuart52 »

Rosco...I couldnt never fall asleep reading your advice or anyone elses......just to interesting!!!

With paint removal......what are the best options, I`m not going to sand blast, dip or bead as I`m on a budget.......and that really puts an end to it!!! So whats the easiest and most economical way in time and $$$??? I`m sure this might have been covered, but since this will be going to the tech archive, we might as well have all the information in the one place!!!

Maybe a basic list of items for the very start of the panel.....say looking at it with old primer, what will i need to start the work??? hahahahahaha....i`m so annoying :? I can see people shaking there heads!!!

Also i noticed in another post, someone used an HR column..........do you have to use the HR steering wheel or can you still use the ek...wheel...if not...whats the eldest wheel that will fit???

I had a brain wave the other day - My brothers good mates dad is a panel beater, and I have asked him if he would be happy to help/assist....so just waiting to hear back!!!

Anything else anyone thinks i should be doing???
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