Part Five, in what is steadily becoming the longest diy tutorial in history is all about applying the primer to the repaired panels.
A quick note before we begin. Always check the local rules and regulations regarding the use of automotive paints. Often times it will be illegal to spray these paints at your home and you may need to look for an alternative location.
In a lot of cities you can actually hire out spray booths by the hour or day/half day and this would be better than upsetting everyone and maybe even facing a fine.
And remember always use a respirator or at the very least some sort of mask. Automotive paints are not kind to the body, plus if you’re off with the fairies the job will probably end up looking pretty ordinary! As you can see my choice of mask does great things for my looks but doesn’t offer much in the way of protection and it scares the hell out of the kids! Seriously though it is very important to always protect yourself.
Always wear a mask while spray painting!
Some Important Basics
Now that we have that out of the way I guess the first step is to go through a few basics before we start the painting.
There is going to be a fair bit of bog (filler) dust around if you have done a repair or two and all of this needs to be removed before painting begins, both from the panels and the surrounding area. Compressed air is good for this however you need to either blow it all out in an area away from where you are going to paint or allow enough time for the dust to settle and then hose the floor down. Be as thorough as you can when cleaning down the panel as any muck that is remaining might just find it’s way onto your lovely new paint surface.
Obviously anywhere that we don’t want the paint to go has to be masked up. A newspaper and medium thickness masking tape will do the job. Be sure to mask every little nook and cranny that you don’t want to paint as over-spray finds it way into everywhere and there is nothing worse than spending a day or two removing it when you could be polishing your new paint job instead. Things like door handles and lights are best removed in my opinion but if that is not possible try your best to take the masking tape right to the edge so you have a nice clean finish.
Before we move on it is very important to wipe the panel/panels down with wax and grease remover. The idea is to use two clean rags, one to apply the wax and grease remover and one to dry it off. Once this is done ensure that nothing comes in contact with the surface as even the grease in your skin can affect the adhesion of the paint. A ‘tac cloth’ can be used after this to remove any remaining muck however I don’t find this absolutely necessary.
Next item – the spray gun. There is two types that are suitable for automotive paints, the suction feed and the gravity feed gun. For applying primer both types are suitable but I have found that for the best top coat results a gravity feed gun is the way to go. Once again I stress that I am not a qualified spray painter or panel beater, this is just what I have found works for me over the last ten or so years of spraying cars. I picked this gun up from ebay for about 80 bucks and for what I do at least it has done very well. The suction feed gun was retired a while ago and from memory it was a Super Cheap job for around the 40 dollar mark. Certainly not high quality but they are good enough for an amateur like myself.
The next thing is the primer itself. If you are keen to get a really good finish on your car I suggest you use high-fill primer or spray putty and spend the time wet sanding it once applied. If you just want to get the colour on and are not too concerned about minor imperfections a primer/surfacer will do. We are focusing on using acrylic paint with this article as two-pack, in my opinion, is best left to the professionals with the right equipment such as a booth, respirator etc.
The first step is to work out our thinning ratio. Generally speaking acrylic top coat and primers are thinned at a ratio of 1 part paint to 1 ½ parts thinners. Use only thinners suitable for acrylic paints, enamel thinners won’t do anything! This ratio is only a rough guide and it should be clearly stated on the tin what ratio is needed for that particular product. We are using an acrylic high fill primer and general purpose thinners and our ratio is 1 to 1½.
I have an old paint gun pot that I use for mixing the paint and have found the best way to measure the amounts is with a metal ruler. It is important that you give your primer a thorough stir before use, it could have been sitting around for quite a while and the heavier parts may have sunk to the bottom. Once again the old metal ruler is good for this. I also suggest wiping the top of the primer tin and thinners container before pouring. As a rough guide you will need about half a litre of thinned primer per panel for a medium to large size car. Before starting it is a good idea to mix up some paint and test your skills on something other than the car.
Which brings me to another point. The spray gun will more that likely have at least two adjustable controls. Your best bet here is to try each one and get a feel for what is best for you. Just a couple of pointers – you want the paint ‘fan’ to be reasonably wide but with enough paint material coming through to maintain a nice ‘wet’ edge. See the video below for an idea of what I consider a good paint flow and pattern.
Air pressure – most acrylic products that I have used recommend a spraying pressure of around 30 psi. I however find that I can get far better results using anywhere from 40 to 50 psi. Now I am not saying that use should ignore what is written on the label but I think the more time you spend practicing and changing around the settings the better result you will get simply because you can get a feel for what works best for you.
Finally, applying the primer.
Ok, on with it already! I will explain as best I can the actual painting procedure and suggest that after reading this you take a look at the video below which should make things clearer? Hopefully.
To start with, what we want is a nice even flow of paint onto the surface. Too little and we will have dry areas that are rough and the paint will be thin, too heavy and we will get the runs ( figuratively speaking). It all comes down to how fast we move the gun and how much paint is being sprayed.
Something that I found took a bit of practice is keeping the gun parallel to the panel. Particularly at the edges it is easy to lift the gun away from the panel. Try to be almost robotic in your movements and keep the gun at the same distance from the panel across the whole stroke. As you do each stroke you want to overlap the previous one by half. This ensures that there is no ‘dry’ areas towards the outside of the paint ‘fan’.
The best method I have found in maintaining a nice even coat is to position yourself and/or the lighting around you so that you can see the ‘wet’ paint edge at all times. We tried to capture this in the video although it may be a bit hard to see. If you can follow this wet edge across each stroke you will get a feel for how fast you need to go and whether or not there is adequate paint coming from the gun.
Next we will cover using a ‘guide coat’ to achieve a better finish and then get on to applying the top coats.
Best of luck! Part Six can be found HERE