Polishing 2-part urethane clear coat

[87 Pete]

How long should you let it cure before wet-sanding and polishing?

24 hours? 36? Longer?

Also, what grit sandpaper, and what type of compound should I use?

Thanks.


Pete

 

[klrv6]

Wait

I always wait at least one week on the good cars (sometimes 3 depends on outside temp) let it set in the sun. My funky little s10 I painted took almost 3 weeks to buff. 1000 blocked - 1200 -blocked - 1500-blocked. Be careful, you can burn straight through the clear!!!! With the 1000 take almost all of the orange peel out, using long strokes in a criss cross pattern. I even buffed the door jambs on my s10. I will try to locate some pics. Always have the buffer rotate off of the part not onto it and go slower with lighter pressure on edges. What brand/system did you go with?

 

[klrv6]

Compound

I have used many 3M & such. I have had really good luck with this stuff called turbo cut. Talk to your auto body supply shop.
This person has a quick write up on color sanding, although he recommends not using blocks but rather harder foam blocks (this will leave slightly more orange peel, it's up to you).
http://66.34.72.138/howto/colorsand/

http://www.customclassictrucks.com/howto/137_0403_paint/

Never use the thick paste type compound on clear coats.

 

[Turbo T/A 1543]

I'm colorsanding / buffing in 24 hours. Read the back of the clear can for recommendations, but in the first 24 hours or so the clear sands / buffs great, but gets harder to work with the longer it sits.

 

[klrv6]

It will die back.

If you get on it too soon it will die back, as all the solvents have not yet left the clear. Yes it is harder but you won't have to buff it again. If buffing within 24 hours plan on a repolish 6-12 months out.

 

[Red Regal T]

I think a couple days is good. But waiting longer really shouldn't cause a problem. How much, or many coats of clear is on the car? How were you planning on going about sanding the car? I start with coarser paper and end up with 1200 in the end. I just use PPG fast cut compound and then something to remove swirl marks. I've heard 3M finnesse is great but they can have it for $32 a qt. I use 3M Imperial hand glaze at the end.

http://community.webshots.com/user/redregalt

 

[87 Pete]

I was using OMNI MC161, I believe it's a PPG product.

I was painting a motorcycle gas tank, and there are A LOT of layers of paint, bondo etc., so I am a bit nervous about the sanding-marks coming thru later.

At any rate, I put on 4 coats of clear, waited 24 hours, and wet-sanded with 3M 1200 wet-or-dry.

Polishing it was a pain, till I got some 3M Finesse-it, and a buffing wheel

It came out pretty nice, thanks for all the tips.

BTW, do any of you guys use fish-eye eliminator? The last coat of clear had lots of fish-eyes/craters. I tried to be very careful, and keep things clean/oil-free, and the compressed air was filtered.

Pete

 

[klrv6]

Oils & Silicone

A "trick" many companies like 3M use is to, add machine oils or silicone to the product. These tricks make you think you did a great job of buffing, only to dry out weeks later when you write off the scratches as wear or from washing. Almost all of the hand glazes do this. Every wonder what used car lots put on paint to make a car look new again for a few weeks. Yes 3M seems to use alot of silicone, check out this company http://www.bodymagic.com/bmbody.htm I used the 0800 then 010 then 020 all three products can be lubricated with the 050 although it does smell moldy. Another thing is to not wax the can for a least 3-4 months unless it was baked on. Wax seals paint, most autobody polishes meant for body shops, don't seal. Oh yea check out the body magic prices, 1QT of 0800 cost around $8 from local shops.

 

[BobbyBuick]

We waited 24 hours and used 1000-1200-1500-2000 wet sanded the top down to 2000 and the sides down to 1500
I noticed after 1 day it went a buch faster than after 2 days it didnt cut near as fast.use a small squeegee to dry off surface to see if their are any shiny spots .Keep sanding if their is plenty of clear till it is all dull .Then Buff WAALAA.
OHH to answer the question IMHO 24 hours IM NO EXPERT

 

[slowsix]

KLRV6....
Thanks for posting the URL on the Body Magic products.
Been looking 3 years for a supplier. Just about out of all of it. Great stuff, beats any 3M product I've used.
Response to original questions: Follow can directions, but at least 48 hours should be good. Grit depends on base color, especially black, go with 1500 as a finish cut. I don't use a block, I use a half of a paint stir stick, yep, wet sand the whole car with it, primer (600 grit), color and clear (1000 then 1500) for that elbow deep look. I still use the old PPG DAU with hardener so I can wet sand the color (idiot proofs the paint system). HVLP systems seem to leave more orange peel than the hi-psi guns (maybe just mine) getting a new Binks M1G soon, maybe it will be better.
Regards,
Howard

 

[klrv6]

Paint stick = block

Sorry,

When I say I use a block, I mean it is a paint stick about 10 inches long. The ones from hardware stores seem to work better (twice as thick).

 

[Red Regal T]

To answer a couple questions, I always use fisheye eliminator. Without it, you run the risk of fisheyes for sure, which is a major setback. I have used a paint stick for years for blocking but just lately I purchased a "durablock". Kind of a hard rubber block that is 11" X 3/4" X 1". Comes in other sizes, also. You rap your whole sheet of sandpaper around it and block away. It's easier to hold and less fatigueing than a paint stick. For more rounded areas, take a piece of scotchbrite and wrap half a sheet around it in thirds. This will avoid making any "finger" impressions. Sometimes a sqeegee added in the folds helps make it flatter if needed. Compounding I use PPG DRX 55 fast cut.

I never use higher than 1200 grit. Doesn't seem to take anything off. May have a use, perhaps for sanding scratches, but I think it's just something to sell. If I'm doing a show job, using a lot of clear, I use 500 to start. These higher number papers, 1200 and up, have very little effect. If you don't flatten out the surface by taking off material, you'll have a finish that looks like a rolling ocean. The more clear you put on, the more paint buildup you will have. You have to make the painted surface flat, like a mirror. Did you ever look in a wavy mirror?

I just started with Body Magic. I didn't want to pay $32 for finesse. I used to use Ebony for years, but they went out of business. The last quart I bought was under $10. It turns out, Body Magic is about 3 miles from my house, so I went over and started off with a quart of their finishing polishes for $22. It's pretty thick and you don't have to use much. I'm happy with the product and for me the convenience of picking it up.

And, buy a binks if you want, but I find the cheap guns to work just as well and are cheap enough to throw away anytime they acts up.

 

[Red Regal T]

By the way, I have a siphon style spray gun w/cup, new in the box, never used, of the same that I use. No disappointments. If anyone is interested, I'll shoot you picture of it. $55 shipped.

Another point I'd like to touch on is, if you have done any bodywork in areas, or used heavy sandpaper, you may get paint shrinking back into the sanding scratches after you have polished out that area. Usually, you can wet sand it out with 1000 or 1200 or lighter and that will take care of it. You may still get a little more shrinkage over time and you'll have to do it again. The only way to avoid this is to be painting over bare metal which may not be possible. Even imperfections in the previous paint job may come back but can be taken care of in the same manner.

 

[Red Regal T]

Originally posted by Red Regal T


I never use higher than 1200 grit. Doesn't seem to take anything off. May have a use, perhaps for sanding scratches, but I think it's just something to sell. If I'm doing a show job, using a lot of clear, I use 500 to start. These higher number papers, 1200 and up, have very little effect. If you don't flatten out the surface by taking off material, you'll have a finish that looks like a rolling ocean. The more clear you put on, the more paint buildup you will have. You have to make the painted surface flat, like a mirror. Did you ever look in a wavy mirror?

Would just like to re-cap..........Always use a block or paintstik when you wet sand. Better a paintstik or block as described in my above post. When you start with the coarser paper as I do, 500, this is the main sanding for flattening out the finish. Of course, stay off the edges. The successive papers you use, just take out the coarsness of the previous paper, so you don't have to sand as much. Last job I did (black), I used 500, 800, and 1200. 500, 1000, 1200 will also work as will 500, 600, 1200. 600 seems to work the same as 1000 grit to me but is much cheaper. Using these grits with a block, compound and polished out, will give you a show paint job, worthy of comment.

 

[first turbo]

paint

i remember one of your posts about synthetic enamel getting close to doing paint could you enlighten me on this paint, is it a ppg product? what about sanding? will be using black. not a expert at paint have painted 2 cars over the years with lacquer.
thanks Don

 

[Red Regal T]

Yes, you can do a black synthetic enamel job that can't be told from the much more expensive acrylic urethane. I use NASON /NASCO synthetic enamel, doesn't do anything crazy, will spray over anything without reacting.........a Dupont product. Black costs around $32 a gallon. Spray 2 gallons (6 or 7 coats) on your car and double up on the hardener. Use Smoothie fish eye eliminator. Let it cure at least 3 days and wet sand as I've described above and put it in a show.

 

[first turbo]

THANKS FOR THE INPUT, WHAT PRIMER DO YOU USE

 

[Red Regal T]

First of all, never, never use lacquer primer. In fact, forget everything you ever knew about lacquer. PPG epoxy primer is a very good primer, though a little pricey. Sometimes I paint over urethane 2K primer. If there's no problem with the paint your painting over, such as checking or cracks, just paint right on it. It depends what you're painting over and what color you are painting. Nason black will cover anything first wet coat. I painted my car with Nason synthetic enamel.

http://community.webshots.com/user/redregalt

 

[first turbo]

MOST OF THE CAR WAS CHEMICAL STRIPED TO FACTORY PRIMER SOME BARE METAL , DECK LID BARE METAL AND HAS BEEN PRIMED IN URETHANE. IWAS GOING TO USE ACRYLIC URETHANE UNTIL I READ YOUR POST ON THE SYNTHETIC ENAMEL. PAINTING THE CAR IN PIECES IN A SLOW PROCESS. THIS IS A DRIVER NOT A SHOW CAR I JUST LIKE IT TO LOOK GOOD. I HAVE FORGOTTEN ABOUT LACGUER CAN'T GET IT AROUND HERE. IT IS BLACK

 

[Red Regal T]

I'd get the rest of that primer off and get the car to bare metal. Seeings you went to that much prep, I'd go for the two part PPG epoxy primer to protect the metal. Then shoot the whole thing in 2K urethane and block it with 320 or 400 for your finish prep before you shoot it.