Spray Painting Tips and Tricks

[threedogs]

So was my first comment to you correct,??
if you can pee you can paint?
A great product for diff coatings is called POR 15 ,this stuff is un real
your Auto paint shop will know of it, pricey as but best for its job IMO

[daves]

That must be why im good at drinking beer

[stevogq]

painted a couple of cars and one very usefull tip i learnt was to spray the putty on the car and get a can of black paint and roughly spray the car so when you sand it back you can see if you have high/low spots and touchup with the spray putty and sand back again and the more clear coats gives the impression of "deeper colour"

[mick.]

painted a couple of cars and one very usefull tip i learnt was to spray the putty on the car and get a can of black paint and roughly spray the car so when you sand it back you can see if you have high/low spots and touchup with the spray putty and sand back again and the more clear coats gives the impression of "deeper colour"

This thread is based on 2 pack so there is no need for spray putty but I get what you mean.

The guide coat is a great idea though and used by all spray painters. Although most use guide coat powders or dies such as Purple Haze now. I personly use basecoat on a rag and soak the rag in reducer and smear that all over the job. That actually gets the guide coat in the scratches so if your going from 400 wet to 800 wet using this method you are garenteed to remove all your 400 scratch marks. With a guide coat out of a gun or spray can it usually just sits on top. Rubbing the guide coat off doesn't mean you have actually removed the scratch marks which is why dies and powders are used these days. Don't do this with acrylic though it will wipe it off. lol

threedogs if your comment is true "if you can pee you can paint" there must be a lot of guys out there with trade certificates who still cant pee on the own let alone backyarders or a lot of guys who have no idea what there looking at.

Cheers Mick.

[Rustyboner81]

True if you can piss you can paint. But it'll look like youve pissed all over it. I got out of painting a few years back now. 2k all the way.

[Timbo]

Righto, I know I can make a call and get this information, but thought I'd post up here so it's all recorded on the forum for posterity ...

Soooo .... the lads rig is not far off paint. Questions as follows from someone who's NEVER done automotive spray painting (except from a can with a ball bearing in it!! lol).

Here goes:

1. I take it there is 3 coats applied - primer, enamel (not using 2pac), and clear coat?

2. Should I apply two coats of primer? If so, why and should it be etch primer? Why?

3. Should I lightly sand the primed finish with 140 grit to remove any small imperfections that come through the coat from the original surface and make it ready for the top coat? If not, why not?

4. When applying enamel coat, how many layers? I sort of understand the actual application process, but unsure whether it should have multiple coats.

5. What is the usual mix of thinners to enamel?

6. I take it the clear coat doesn't require thinners, but if so, what mix?

7. How many coats of clear?

So basically, it's a big "I've never done it before, want to have a lash, but don't want to stuff it up" bunch of questions.

Any and all assistance and advice greatly appreciated!

I'll try and answer your questions for the sake of it. I don't think anyone has tried to yet.

1. Number of coats can depend obviously. In general, your pretty much right. With metal, I use an etch primer first to bite into the metal, then prime over it, either with a filler primer if there's light scratches or a surface primer if body is fine, then your paint plus clear if you need clear.

2. As above, for metal, I'd use an etch primer first so it bites in. Normal primer was hang onto etch primer easier than bare metal in most cases. Number of coats can depend on how thin your primer mix is. Might be 2:1, 3:1 etc. If it's thin, you could afford to apply a couple coats. If it's thick then one should suffice. Depends on if you have to use bog on the primer too. If your sanding the primer back, which you should be, then you want a bit of lee-way so you don't rub through the coat. Think of it as a buffer.

3. After priming the surface, you usually apply a guide coat which is usually a REALLY pissy black colour that you spray with a lot of Air and minimal Material. You set this on the gun. This helps to find high and low spots when rubbing back. 140 grit is pretty rough. I would think more like 400 or 800grit wet and dry paper would be reasonable. The rougher your paper is, the more marks will show in the paint.

4. Haven't sprayed much enamel, but from memory 3-4 coats is good. A simple rule I found was "tack coat, colour coat, glass coat". So first coat you dust on some colour to the primer.. some call it a haze coat. Then your second coat is going for colour. Basically lay colour down so you can't see the primer but not too much that it's running. Glass coat is obviously a finish look. For Clear, you can use the same theory but it's harder to see results unless your in a very well lit area like a booth.

5. The paint tin will have your mix ratios on it. It varies between manufacturers.

6. Same as above really. I can't see why you wouldn't use reducer with clear. All the paints and Clears I've dealt with used a thinner or reducer because it's too thick otherwise.

7. As per 4. Normally 2 coats is fine. You can apply the tack, colour, glass rule to the clear as well or just two decent coats if you know what you're doing.

If you're keen to do it, try a door first or a piece of sheet metal etc. Get comfortable with overlapping your spray line. There's many factors to painting that can make it hard and daunting, not gonna lie. I'm in no way a pro painter but I learned a lot over 2 years of doing signs. A lot of signs were much larger than a car too. The process is the same, it's all metal.

So grab a piece of sheet metal and try. If I was doing a car in a solid colour (not a metalic or pearl) I would break the car up into pieces. Take off all of the doors, guards and bonnet. Lay them all down on tressels flat. Much easier to spray. Then do whats left of the body starting at the roof.

Temperature is one of the biggest things to watch. If it's too cold, don't try. Too hot, don't try. Find the ample spray temp for the brand your using and do it at that temperature. Easier in a booth but you might have to wait for a nice sunny, wind free day if doing it at home.

[mick.]

I did a detailed write up earlier in the thread on 2 Pack which is the same as enamel. All enamels should be used with a hardener to get best results.

Timbo for future reference never put more then 2 to 3 as a last resort (not covered) coats of enamel on anything. It is to much paint and can run very easily plus there's a very good chance of solvent boil.

Cheers Mick.

[Rustyboner81]

Too many coats can result in crazing and solvent pop. Crazing shows up as fine cracks in the paint finish. Solvent pop shows up as pin holes. Both are caused buy paint film thickness. Popping more in enamels where the surface tacks off and the evapourating solvents pop through the tacked off film. Crazing is caused buy the paints film being to think and contracting as it cures.

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[Aldrich08]

Well i think there nothing bigger tips then it that you just shake the spray bottle and then don't stop your hand when you are spraying. Because when you stop your hand on one place then it lead to the over paint on some places.