I'm using Dupont ChromaSystem on my car. In the technical manuals, it lists a few different sealers for the URO primer-Filler 1120S/1140S. But in the manual for the ChromaBase Basecoat, it lists both URO Primer-Filler AND the sealers as substrates. Does this mean I can spray the basecoat over either one, or do I need the sealer?

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Rob F.
TC member 312
68' SS396 6-spd EFI Elky

Hey Rob, forget the sealer, you'll be throwing away money..
The only time I use a sealer is going over another type of paint that doesn't require uroprime.

RandyB.. www.angelfire.com/ky2/mycars (http://www.angelfire.com/ky2/mycars)

I respectfully disagree here, I've always sealed after primer/filler. It gives less bleed-through and you can match topcoat colors more closely for a more uniform color hold out. Not to mention less topcoat color if you're clearing. Also the sealer makes a great guide-coat and gives a final opportunity to do a once-over. Catch something you might have missed in the dull primer/filler. To each his own, however, I'm sure it's been done both ways. Just my biased opinion.

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'68 SS-396 1/4 stroker "54" (soon)
'99 GMC 7.4 Vortech
'01 T-Cat 1404 Hooper 2X156"
"no replacement for displacement"
-2 Below Custom Automotive
Fbks, AK.

good points by both, I tend to use a sealer.
only if there was alot of body work on most of the car.

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Wayne
ACES 1556
TCG 186
So many Mustangs
So Little Time

I say use the sealer.On my car i sprayed uroprime blocked it and sprayed Chromaone over it.And now five years later i have a lot of weird stuff coming up though the paint,Chemical pop ect.Not to say sealer would have stopped it but thats why they make it.

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70 chevelle,400cid turbo400.blue with silver stripes.
http://members.spree.com/entertainment/ochrisl/

I had been painting for almost 20 years, self taught, and used sealer EVERY time. Then I went to a S-W tech school. After learning what a urethane primer is and how it works I NEVER use sealer. If you have a properly applied urethane primer (I know that sounds like a "dig" or a smart a** remark but it is not, if not applied properly you have have things like solvent trapped that wil soften the film) and you sand the primer with 400 or 500. You will have ZERO shrinkage your paint will look the the day it was shot years later.
The urethane primer (or any 2K) is (if a quality product applied properly) non-soluable and will take the color coat perfectly.
There are reasons to use a sealer, but if you have full panels 2K primed, with littel to know feather edges, you do not need it. It will only cost you more money and add texture (read that "orange peel") in the top coat.

As far as color for the color coat to cover, well this mayt be an issue, but it should be corrected with the primer color choice or with the color coat choice. BUT there are times a sealer should be used because of coverage as the "bestest fastest" way to solve the problem.

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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"

On the bike I just painted I used sealer on all of it, and had to "Redo" some work on the tank because of lifting.. took the tank to bare metal, 2K primed it and painted. I feel the paint flowed better and covered just the same. So I guess it's up too you..

I dont know about "zero shrinkage".2k's definatly hold up better to shrinkage but theres always some.Uroprime is a three component prime.One being a reducer.Reducer = shrinkage.newer primer like 4004 has no reducer.Also the basecoat can shrink back into the 400 - 600 sandscratches in your primer.That is one reason Dupont has the non sanding sealer, so that your not sparaying your color over a sanded surface. Everyone has their own opinion,probably either way would work fine.If the point is to save money,skip the sealer. http://www.chevelles.com/forum/smile.gif

Thanks for the replies guys. The URO 1120S I have is light grey and is very close in color to the metallic silver basecoat, so I don't think I'll have any color/coverage problems. And, this is pretty much a daily driver, so I'm not trying to achieve a "perfect" show quality paint job. I think I'll try it without the sealer. I have plenty of time to play around with it and get it right.

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Rob F.
TC member 312
68' SS396 6-spd EFI Elky

70isfine, I have to agree with you I shouldn't have said "Zero shrinkage" But ALL products have solvent (reducer). Some you add it ( add "more", actually) and others have it in them already. What I was saying about "properly applied" is if you apply it properly there will be little solvent left on in the film and then it will shrink much less. Some products (like anything low VOC) will be much tougher to pull this off. The acetone used to reduce these low VOC products is very heavy and hard to "get rid of".

As I said, it is a toss up in many different projects, but I have found that the sealer will shrink just as much as the base coat so it is a self defeating step.

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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"