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My Method of Spraying a Car

by Nigel Warner

I have been painting cars, mostly on an every now and then basis ie. when I have restored a car, for over 30 years. The following is meant to be an aid to getting a good finish on your car. The methods I’ve described below are how I have done it on a trial and error basis over the years and are not necessarily the correct way but the way I find gives a good finish. You can hire spray equipment at a reasonable cost but I have found in the past that the spray guns are not necessarily always cleaned too well and have bee use for spraying things other than cellulose paint. Once I found traces of creosote. If you are going to do this more than once it is better to buy at least your own spray gun (saves cleaning out the hired one before using it) or possibly a compressor as well. The one I have used for many years has given me no trouble and cost about £100.

Preparation

I always spray outside on a hot or very warm day with little or no wind as I find my garage, being a single, isn’t big enough to do it very easily. After preparation hose down the floor and try to keep the floor damp during the painting of the body (to keep dust down). Remove all the trim, glass, etc if possible or mask up the areas not to be painted. If you are leaving the glass in I find that if you lift the rubber where it meets the body and put some rope or wire under it the rubber is kept proud of the body and you can spray underneath a little and don’t get a nasty paint edge.

Rubbing Down

First thing to do is to decide how bad the paint is and if it’s been resprayed before.

If you are in any doubt take the paint back to bare metal or gel coat. If there are too many old coats and/or a mixture of 2 pack & cellulose this can easily cause you problems later on. If you are thinking about doing a respray in 2 pack paint and are spraying at home or near other homes then DON’T. 2 pack is designed for professional use and is not healthy to people or animals. You will also need special breathing equipment. 2 pack is also harder to rub down, and it is difficult to correct any small mistakes. This is one reason I use Cellulose and the other is that I think it gives a better finish and it’s easier to blend into existing paint if you are touching up a small area.

Stripping the paint.

Etch Primer

If you have gone down to bare metal or gel coat it is recommended that you use etch primer but I have never used it and haven’t had any problems but the decision is up to you.

Spray Putty

This is really good for giving a bare shell/panel or a largish dented area you have repaired a good coat to work with but you can just use more coats of primer surfacer.

Primer

If you have decided to paint over the original paint, rub it down then repair if necessary. You can spot prime any repairs and rub down with 320 wet & dry but I prefer to prime over the whole area being painted as it gives a better finish and will show up any problems earlier.If you go for the bare shell option I always give the surface 3 coats with a mixture of 50/50 primer and thinners going over any repairs first. You don’t have to worry about runs too much at this stage.

Painting Sequence

When spraying a complete body shell I always spray any openings first such as door, boot and bonnet before starting on the roof. Spray a line down the centre of the roof, then work back towards yourself until you reach the gutter. Move quickly to the other side of the car and then do the same. Make sure the gun is about 7-12 inches from the roof and as square on to the panel as possible. You are aiming to put a good wet coat on the roof with a 50% overlap at each pass. From the roof move to the rear and spray any horizontal surfaces and then do the same at the front, this mainly applies if you have not removed the bonnet or boot. Once all horizontal surfaces are done move to the side you started from and paint the rear wing from the roof down. If you haven’t removed the doors then I would have thought it would be easier to have them open and then paint the front wing. I then move to the front of the car and paint that before moving on to the other side and then the rear. If the doors are left on I would leave the car to dry over night and then mask the wings etc and paint them separately the next day. I must admit I have always removed the doors, bonnet and boot and sprayed them separately with them either suspended from the garage rafters or stood up on pieces of wood.

Leave the car overnight if possible to dry out.

Priming and final coat painting of panels.

Guide Coat

Any cellulose will do for this, but preferably the same or lighter colour than the finished job. Mix guide coat to 70% thinners & 30% gloss, and then spray lightly and quickly over the shell. You are aiming to just have a mist coat all over the car.

Rubbing Down The Mist Coat

Rub down the whole car with 320/400 wet & dry using plenty of water and a good rubbing block. Do not use circular motion as this always shows through the top coat. Any imperfections will stand out in the guide coat. You can then spot fill any low spots as required with more primer or spray putty and rub down with 400 wet & dry. Any high spots will require lowering with a hammer & dolly and then refilling.

Base Coats

Mix the colour 50/50 with good quality thinners. Spray pressure should be about 50 to 60 PSI. at the gun. Before painting it is best to remove all the masking paper and re mask.(this stops any loose dry paint on the masking from falling on to the fresh paint). Clean the body with clean fresh water. Blow off any excess water, paying attention to gutters, door edges, intake ducts etc. and make sure the car is thoroughly dry by leaving it out in the sun for a good few hours. Use tack rags and lightly rub over the prepared area. Using the same sequence as before, coat the car with a good wet coat making sure you overlap 50%. Put plenty of paint on the edges of all the panels and swage lines. Once you have been around the whole car do it again starting from the same point. The whole car should take about 2 to 3 litres of paint mix. You are aiming for a nice wet finish without too many runs. Don’t worry about runs at this stage. If you have got them, then leave the car overnight. Flat out the runs with 800 paper & block.

Final Coat Preparation

Once you have rubbed out any runs, flat the whole body with 800 paper and block. You are aiming for a uniform flat finish. Check the body for any faults and rectify them now. (Spot prime, flat with 600, spot with colour, flat with 800).

Wash the body with clean water, leather off & blow down. Tack rag using light strokes and leave in the sun again for a good few hours. Mix the paint 60% thinners 40% paint. Make sure you mix enough to coat the whole body twice, (about 3 litres mixed). Use the same sequence as before, putting on two coats back to back. Aim for a nice wet finish.

Final Finish

If you are happy with the finish then leave it for a few days and use T Cut.

If you want a better finish then flat with 1200 paper used with a little hand soap to lubricate the paper. Wash the car then use polishing compound (Farecla G7).

Then finish with T Cut. Do not use wax polish for at least 2 weeks as you could end up with lots of little white dots all over your nice shiny paint.

Important

It is very important that the car is completely dry before spraying as any moisture can get trapped below the paint and can appear even years later as small bubbles of water under the paint. I always choose a very warm day to spray and also I make sure the car has been left out in the direct sun for at least 1 day before painting as this will dry out any trapped moisture. Also try and use a moisture trap in the hose from the compressor to the spray gun.

Disclaimer

I won’t be held responsible for any damage or misfortune that may occur as a result of your following my method of preparation and spraying as it is only intended as a guideline.

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