Ok as the title says its basic but from other forums I have tended to gather that painting is a black art only to be undertaken by the chosen few . Lets put this record straight right now.
A bit of background here . I have been painting for the last gawds knows how many years cars . It's my trade and something I can do quite easily and with no thought at all . I was asked a while back if I could write a basic tutorial on painting techniques and after a bit of thought I did.
Believe me it took a LOT of thought to actually write down something that is automatic to me each and every day and try to make it understandable .
So below is the result of my efforts .
Bear in mind that I paint cars for a living and the tutorial was made for rc aircraft builders but the techniques remain the same .
If you have any questions please feel free to post them or PM me . I look in at least once a day
Shane
Preparation
This is most probably THE most important section in this article, without good preparation you are simply wasting your time, effort and money.
So what does good preparation entail?
For the purposes of this guide it is to be assumed the object to be painted is already glassed , or finished ready to accept paint .
Firstly you need to make sure that any imperfections are taken care of. Small dents can be filled with Balsa filler or a product made by 3M called Acryl red, a very fast drying lightweight and easy to sand filler used in the car repair business.
High spots can be sanded away using fine 800 grit wet and dry sanding paper (used wet) on a small rubbing block .Once you are sure that the surface is as smooth as you can make it ,you can move onto using primer.
For this guide we will be using car aerosol primers, as they are readily available and ideal for the job in hand.
What colour primer?
A good question, there are a multitude of colours available but as a general guide, try to imagine the top coat being opaque and you can see the primer underneath. Ask yourself if the primer colour detracts from the topcoat colour.
I.e. you wouldn’t put dark grey primer under a white topcoat. Then again you wouldn’t put a white primer underneath a white topcoat either because it is very difficult to see where you have and haven&undefined;t painted.
Try and find a colour that is either a close variant or one that will enhance the topcoat.
Light grey primer will suffice in the vast majority of cases, white is good under bright colours like yellows and reds.
Also get a primer of a different colour to the one you will use , it will be beneficial during the preparation stage.
So your ready to start priming are you?
No .............. You still have preparation to do first.
You are satisfied with the finish ready for the primer, what else is there to do?
CLEAN UP!
At the very least you should have a good sweep of the workshop and work surfaces to get rid of as much dust as is possible.
Dust is one of the main reasons a paint finish looks bad. So make sure the area you are painting in , is clean.
Don’t paint in the cold either, a warm environment is better for the paint as it flows better, take this as meaning each paint drop from either can or spray gun flow together creating a nice smooth finish.
Make sure you have adequate safety equipment for yourself as well; rubber half facemasks with screw on filters are ideal for the job. Believe me you DONT want to fill your nose and lungs with paint vapours, apart from the looks you will get when blowing your nose to remove brightly coloured mucous, do you really think lungs were designed to be painted on the inside?
Ok let’s start
First we need to make sure that the surface is totally clean so we use another couple of automotive products for this job.
We need to make sure that there is no grease or oils on the surface as these create fish eyes in the paint, which are very hard to remove without rubbing the paint away completely. So we use a product called panel wipe /spirit wipe which is a gentle thinner. It’s important to use 2 different cloths for this 1 to wipe the solution on with the second to wipe it off with; this ensures you are not just pushing the oils around.
Next up is a "tack" rag which is exactly what it says ,a tacky rag !!, this is lint free so will leave no residue on the surface. The tacky covering it has will pick up any remaining dust from the surface.
Now we can start priming.
For the first coat we need to very lightly cover the surface with a single "dust coat", NEVER EVER try to put any primer or paint on with one good thick coat, you will get a terrible finish that will need removing.
Build up to the finish.
The second coat can be applied after the first looks dry but is still tacky, (flashed off); this coat can be thicker than the first but don’t go overboard with it.The third and any subsequent coats are applied in the same manner.When you have a nice smooth even finish you can consider the job “primed “.Allow the primer time to cure and harden off, usually about an hour will be fine in a warm environment. Then take your second and differently coloured primer and dust a light coat over the top of the finished job.Now when you rub this down with 800 grit wet and dry paper (used wet) you will be able to see low spots in the surface (the second colour will remain).These low spots can be filled with 3m’s Acryl red, a very light and easily sanded filler that dries very quickly. By this stage you should of removed most of the primer that you have applied leaving a very smooth finish.All “dings” now filled? Apply another coat of primer, again , building up from a dust coat to a top coat. Then rub down again, use wet, 800 grit wet and dry sandpaper on a small rubbing block .You should now have a very smooth surface ready for painting .
CONGRATULATIONS!
Materials used in the above are generally available from good motor factors stores like Brown Brothers . You may struggle to find these materials in Halfords.
Now you are ready to paint !!
Equipment
For this we will be using a small touch up gun and an air compressor with a 25 litre tank. A tank of that size will help to ensure an adequate supply of air, at a constant pressure, without the compressor continually recharging itself .
The spray gun, to do its job effectively, requires air at an even pressure and a constant flow.
While smaller tank volumes can be used, there is always a danger of the gun being starved of air and the compressor will constantly be recharging the tank.
Using the spray gun.
Don’t be fooled into believing it’s just a case of pull the trigger and a fantastic finish will appear.
Practice with your gun, with your chosen paint, on some scrap material, before committing to the job. This practice will enable you to improve your technique and learn about the limitations of the paint and the spray gun.
One of the biggest mistakes people make is how they actually move the gun from side to side.
Practice moving the gun whilst keeping the spray head the same distance from and parallel to the surface. This will ensure an even coverage of paint.
If the gun is moved in an arc, a common mistake, this causes a heavier build up of paint in the centre of the arc and light coverage at the outside edges.
The secret here is to be able to move the gun while bending your wrist to keep the gun at the same angle to the job at all times .
When you are confident you can apply an even coverage of paint, it is time to think about the next stage.
As with the primer, top coating, is all about careful preparation. Clean up again and carefully mask off all areas of the model, or surface, that do not require painting.
The best material for masking large areas is masking paper, it is commercially available, not expensive and can be obtained from your paint suppliers. Newspaper is OK, but because of it&undefined;s porosity, two or three layers should be used to prevent the paint from soaking through, and spoiling the finish underneath.
Normal masking tape will be fine, and as long as your primed surface was well prepared, you will not damage the surface when removing the tape.
Time to paint….
Wipe the surfaces over with panel wipe, one rag to apply one to remove. Then use a tack rag to remove any traces of dust.
You are now ready to go.
Load the gun with mixed paint, put your face mask on, and apply a gentle dusting of paint over the whole surface. Try to overlap each pass of the gun by about 50% of the pass before, this will ensure a nice even coverage.
When this coat has flashed off you can apply a second slightly heavier coat. This should be just enough so that you can barely see the primed surface . Let this coat flash off and then spray a third heavy coat. Make sure that this coat is not too heavy or you will start to get runs in the paint.
If runs do appear, DON’T panic and try to wipe them off. You will create a bigger mess. Instead let the paint dry thoroughly and correct the problem later.
The term “flash off” in case you were wondering refers to the point where the solvents in the paint have evaporated enough to give the appearance of dry paint when actually its still wet . This will become clear as you paint .
Troubleshooting
Runs in the paint.
When the paint is thoroughly dry, these can be removed by rubbing back with 1500 wet and dry sand paper, used wet, on a small rubbing block. Don’t worry if you rub through the paint you can always dust over with more paint to blend it back in.
Orange peel effect.
Either caused by working in too cold an environment, which prevents the paint from flowing smoothly, or applying the paint too heavily.
Simple remedies are keep the work place warm and practice your spraying technique. If you do get this effect it’s a case of rubbing down with 800 wet and dry, used wet, until its smooth again, and spraying another top coat.
Very dry paint.
Feels rough to the touch, like fine sandpaper.
This is the result of spraying too far from the surface, causing the paint to be almost dry when it hits the last coat.
Remedy as for orange peel
atchy areas.
A result of bad painting technique, you have not overlapped the passes and some areas have received more paint than others.
Go back to your test surface and practice spraying an even, consistent coverage of paint.
Foreign bodies in the paint.
These are bits of dust, and everyone experiences them, the paint soaks into the dust and builds up around it, creating these spots.Only one way to deal with them, and that’s to rub them away with very fine wet and dry sandpaper, used wet. I would start with 2000 grit and work up through 4000 and 8000 until the spot has gone.
For multiple colour schemes and camouflage, the paint techniques are identical, there is only one rule to remember, and that is, to paint the lightest colours first. It is easier to paint over a light colour with a dark one, rather than the other way around, and also uses less paint. Less paint = less weight.
Happy painting and if in doubt practice first on scrap material.
Have fun and bear in mind this was written for model aircraft but the principles are the same as are the techniques
Shane
ps any questions I might help with pm me
Practice makes perfect.