Paint question

[Rob M.]

Hi all,

I'm afraid I finally bit the bullit and decided next year to do a fresh paint job on our car. Since I would like to have it as close as possible to original I decided to go for the real thing: urthane laquer

I already have found a supplier for it and also have the correct paint chip for it but I have still a few minor questions:

1) How much paint do I need per layer for the whole car ?
2) Does it hurt to spray 4 or 5 layers on the car ?
3) What base should I apply under the paint and how many layers of this should be applied ?
4) What size nozzle should be used to spray laquer ?
5) What spraying distance should be obtained ?
6) How much time do I need to wait between each layer sprayed ?

thanks as always,
Rob.

[Michael H.]

Re: Paint question

Hey Rob -

Corvettes used nitrocelluose lacquer and then acrylic lacquer. I'm not sure they ever used urethane lacquer.

[Keith B.]

Re: Paint question

You should get a full 2 gallons of color. You will need 1.5 gallons of grey primer. I have about a quart left over of color on my 67. Make sure you seal the fiberglass first then use primer. I sealed mine with a product called Rust Defender sprayable filler (1 gallon). You will also need about 5 gallons of thinner mid temp. My car has 7-8 coats of paint that was wet sanded after the 3rd or 4th coat. The laquers of today are very soft and will scratch very easy. We used 3000 grit paper to wet sand after the car sat for nearly a month in color. I used PPG products and was very satified. The judges make me pull color because the paint is a little too nice but there is not a drop of clear in the paint. Good luck.

Keith

[Mike M.]

Re: Paint question

Also use the slow thinner with the paint. You can use the faster (cheaper) thinner for cleanouts.
H. a. N. D.

[Chuck S.]

Re: Paint question

"1) How much paint do I need per layer for the whole car ?
2) Does it hurt to spray 4 or 5 layers on the car ?
3) What base should I apply under the paint and how many layers of this should be applied ?
4) What size nozzle should be used to spray laquer ?
5) What spraying distance should be obtained ?
6) How much time do I need to wait between each layer sprayed ?"

Urethane lacquer? Maybe this is a difference between European and US terminology, but I have never heard urethane called lacquer. In PPGs system, urethane is "acrylic urethane"...no additional description. PPG acrylic urethane is a single stage product, meaning it does not require clear on top. They also sell two stage products that must be topcoated with urethane clear. Typically, a "layer" is referred to as a "coat".

1. Varies depending on the system. Refer to the paint manufacturer's data sheets for acceptable products below, and on top of the paint being used. Typically, you will have a primer coat, then maybe 2-4 coats of primer-surfacer (sanded between coats), a sealer coat, 2-3 color coats, plus 1-2 clear coats if you are using a two stage system. I haven't painted a Corvette, but on my 4Runner (larger than a Corvette), I used about 1.5 gallons epoxy primer, 2 gallons primer-sufacer, 1.5 gallons of color, and 2quarts of clear. Be advised that it if you have to buy three quarts, you may as well get a gallon...the price is the same.

2. No. See above. Four or five coats would probably be typical of factory production, but not the usual way to get a good paint job today. Call me an "over-restorer".

3. Again it depends on the system you chose. Stick with the same brand products that are compatible according to the manufacturer's data sheets.

4. A typical paint job will require maybe three or four different nozzle sizes in a professional quality spray gun...HVLP is the new technology. Sata is an excellent gun that will give you really nice, high gloss, nearly orange peel-free finish if you know what you're doing. For an epoxy primer coat you will need probably a 1.4mm fluid nozzle with matching air cap and material needle. For the primer-surfacer, you will probably need a 1.7-1.8mm fluid nozzle set, for the sealer maybe 1.3-1.4mm, for the color probably 1.3mm, and if you are using clear, maybe 1.2-1.3mm. Be advised that nozzle sizes can vary somewhat with different gun brands. Those nozzle sizes are what I found to work for PPGs acrylic urethane system using a Sata NR2000 HVLP gun. I sprang for the Digital 2 that has the micrometer pressure adjustment built into the handle...Set 2 bars (29-30psi) at the gun and confirm pressure easily while painting...no extended length and weight from a separate micrometer gage.

Edit: I actually didn't spray full clear, but a 50/50 mix of color and clear on the last coat. Even with the 50/50 mixture, the lower viscosity of the clear was obviously felt in a greater tendency for "running" with a 1.3mm fluid nozzle. For full clear topcoats, you will need to reduce your fluid nozzle diameter and/or turn in the material needle to avoid runs. With the Sata, your nozzle set is probably going to need to be 1.1-1.2mm for 100% clear topcoats.

5. Sata recommends 13-17cm with the material needle fully open...that is about the distance between the end of your thumb and outstretched fore finger. I found that to be pretty close for a guy used to a Sears' siphon gun. Consider that to be a setup for a pro that knows what he's doing...if you don't keep the gun moving in a spirited fashion you will be in "Run City".

6. It depends on the product and what the next coat will be. Epoxy primers can be topcoated with the first coat of primer-surfacer in 30 minutes to an hour depending on the catalyst used. If you are spraying successive color coats, the required "flash time" between coats may be 5-15 minutes, again depending on the catalyst used. All this info should be on the manufacturer's data sheets for each product...if the manufacturer has no data sheets or poor data sheets, I would find another paint manufacturer. All this information is essential for good results.

[Rob M.]

Re: Paint question

Thanks all for this great extensive response...

greetings,
Rob.