Paint Experts What The F%$$ Happened!!!!

a little back ground for ya to maybe help me figure out what the hell happened here...cab was blasted, bodyworked, epoxied, fill primed, sealed with the same epoxy, sanded with 600grit, cleaned then painted, couple days later color sanded and buffed. this was over a month ago.... i primered the cab the other day so i masked off the fire wall used the green 3m tape. removed the tape today and it peeled off the paint easier than my buddies sister.. i could see it lift the paint but not rip it up in some other spots. it did not stick anywhere. the epoxy stuck bitchn so what the hell went wrong? the epoxy is the 2k stuff and the paint is a Dupont/Nason single stage that i was told was comparable to the ppg single stage i usually use but they couldnt mix the color in a single stage i guess. i have never used the dupont before... i dont paint all the time but ive sprayed around 10 cars with great results..planed on painting the rest of the truck tomorrow, but now im afraid to spray it until i figure out what i did wrong... SO WHAT THE HELL!!!

 

How much time between the final coat of epoxy that you sanded with 600 and the application of colorcoats? If you waited several days and then sanded with 600, The epoxy is too hard to get chemical adhesion and 600 grit is too fine to get mechanical adhesion.

 

WTF DUDE????????? Is that a pile of paint on the floor? Looks like it just didn't bond. Looks like you covered the whole thing with vinyl graffics.....

 

X2- I'm not a professional. But this is what it looks like to me.
Frank

 

epoxied in the afternoon, sanded next morning and sprayed later that day.. maybe i applied spray wax instead cleaner

 

what bumpy said....

On the plus side, it's peeling off! Get the rest off, rough it with a red scotchbrite and shoot it again(with PPG this time----haaahahaha!)
Sorry for your loss of time and materials, though

I'm not a big believer in sanding epoxy, fwiw.Primer, yes.....but epoxy...never more than a nib raking if it looks dirty. I use it strictly as a sealer, following with color after flashing.

 

It looks like it just flat out isnt compatible with one of the products. Primer or paint.
I never seen it come off like that.

 

Looks like a real bad dream .

 

Well the obvious thing here is - No ADHESION! But damn, its pulling off in sheets? Is this April fools? 600 is too fine as the other guy said. You need around 320 depending on the product. Read the tech sheets for the base. Maybe PPG can tolerate 600 but the DuPont can;t?

 

I don't use epoxy primers at all. I've had perfect results for 20 years from urethane primers, so to me it's "overkill". The only advantage I can imagine is as a moisture barrier, if you aren't going to use paint designed as a topcoat.

I can offer this.....I blocksand primer using 360 wet or dry, and the basecoat paints fill the surface just fine.

You might talk to your paint store. A good working paint system requires getting adhesion between each coat. This involves drying time between coats (not too long...not too short), sometimes sanding between coats, using adhesion promoter when in doubt, and understanding the chemical aspects of adhesion. If you miss something important on one coat....that will be the weak link. I would try to determine which two layers did not adhere.

Being a painter is a trial and error learning curve. The guys who have done this for many years, have been in the position you are, more than once. Don't give up. It gets a little easier as you do each job.

 

Ive seen this happen before and 600 Hundy is way to fine for paint ...
switch to 400 or 500 grit... clean then paint.. good luck

 

i actually think i use 500grit on the firewall when i did it. it turned out pretty orangepeely that is why i waited for it to dry to sand it. ya im goin to the paint store tomorrow to see what they say. neither one of the girls i talk to at the paint store was there today so hopefully if i have to buy more they ll hook me up alittle. sucks, i have almost a full gallon left and im afraid to use it!!

 

Don't be afraid, just make sure you rough it up enough before you put the base on. I wouldn't go over 400 until you're ready to color sand.

 

Epoxy when used as a final sealer does not nead sanded and should
be sprayed with top coats within an hour or two. Same day for sure.
Sanding gives paint teeth to lock into. 600 is tiny teeth.

GM had a rash of peelers in early 90s. I figured they were Friday preps that didn't get final paint till Monday. Paint around door and window openings stuck like glue, everywhere else would come off
like your pictures. the sealer just got too hard over the weekend for paint to stick. They needed to scuff with 320 or 400 , spray a midcoat adhesive coat and then finish coats. A straight edge razer
blade in a holder works great to carefully shave a peeler.

 

320 or 360 grit is what i would do then hit it with the paint you have, it should be ok . i never go over 400 grit for the final sand unless im doing candy graphics over flake or something like that.

 

The only way to make sure is to contact the paint rep for both paint and primer
they will tell you fer sure... sometime's the guys at the paint store dont know shit and sell ya stuff ya dont need... and try to get your hands on some tech sheets..

 

Talk with your paint store. 320 - 400 grit max, the 600 is way too fine. But even at that I'm leaning toward an adhesion problem from incompatable products. I can't see it pulling off that easily from just the 600. Always stick with the same product line / manufacturer to minimize problems. Best of luck with the rest!

 

ya ive never had a problem with using 600 grit, but then ive never used nason either. i usually do not let the epoxy dry forever, i always stay within the window alowed on the back of the can. well i probably wont get to paint tomorrow now, and wont be able to make the hamb meet at pomona. when i paint stuff for myself everything usually works out fine... do it for other people and.........

 

Hey Matt,

That Nason product, is it a synthetic enamel? I haven't shot any of
Nason's product in years, but it wasn't that great 25 years ago!
Cheap and good should never be used in the same sentence, when
paint is bein' talked about.
As mentioned above, too long a "flash time" on the epoxy primer,
and 600 grit for a final sanding were the kiss of death for this paint
job.

Swankey devils C.c.

"Meanwhile, back aboard The Tainted Pork"

 

clean . sand / clean and spray a small area with the paint you have to make sure its gonna stick.....


good luck.

 

Here is a tip, although it is probably not why you had a problem. When you lift the tape be certain to pull it at the most extreme angle possible, that is, do not pull straight away from the painted surface. If you pull the tape straight up you will put the most stress on the paint possible. This is generally not a problem with fully cured paint, but with fairly fresh or fresh paint it will save you a potential problem. As urethane dries is also shrinks which makes the paint "tighten" on the painted surface. Good luck.

 

600= no sticky

 

Stick a fingernail in the primer under where the paint peeled to see if it leaves a mark or dent in the primer. This tells you if the primer is soft and maybe not fully cured and still releasing solvents. Primer that isn't cured may absorb solvents from the paint partially into the primer film and when the paint cures solvents may be trapped between the paint and primer. That peeling and the flexibility of the paint film could be from trapped solvents between layers. Double check the hardner ratio for both primer and paint. A little short on hardner for either one can result in slow or partial cure which lets the solvents soak in. Also how warm was the weather (day to nite temps). Warm days and cool nites may have slowed the cure of the primer and when it warmed up it released some solvents. Primers and paints with hardners will still dry in cool conditions but may not fully cure or let the hardner crosslink with the resin. They will sand OK but the film wil be more susceptable to absorbing solvents.

overspray

 

All of the guys have good suggestions, too fine a grit, not enough cure time, (I don't have any problem with sanding epoxy, but I use HOK), perhaps the cheapo Nason paint had problems?
I didn't see oone possible cause mentione, though. I had another guy prep a car, and it did the same thing as yours. He used Prep Sol for a final cleaning before painting. PrepSol is a petroleum based cleaner designed to remove wax and grease, not as a final cleaner for paint. It leaves a bit of a film behind that paint might not stick to. What did you use as a final cleaning agent? It must be specifically designed for final cleaning, no residue left behind. Also, it must be applied correctly...sprayed or wet applied and wiped off with a clean rag before drying, or it just spreads contamination around, instead of removing it.

 

what you have there is chemical incompatiblity. Even sanded with 600 grit, the paint will not peel off in sheets like that. That is NOT a sanding related problem.

 

brianangus is right, many paint manufacturers recommend from 400-600 grit final sand for modern urethanes.
I think chopolds may have it , if you mixed your substrates properly and followed recommened flash and cure times. You must use a alcohol based final prep cleaner.
Note: ask your jobber for P-sheets on the products you are using. Do not use the can instructions, it's minimal information.

Taking a close look at your picks, you'll notice the sealer is the coat that lost adhesion, not the top coat. It came off with the paint.
Good Luck has nothing to do with it... we make good paint jobs happin', Frank

 

what temperature did you shoot this at? and is there a "hardener" that goes along with that paint? or is it sopose to have it mixed into it? either way dupont sells a Adhesion additive... i dont know if that helps at all...

 

25 years ago, I had the exact same problem. I was new to painting and decided to paint a firewall with Rustoleum primer and shot lacquer over it. The paint peeled off like a vinyl sheet, exactly as your pictures show it. I believe your whole problem is due to chemical incompatability between paint & primer.

 

I am not a professional painter by any stretch of the imagination, but I too am using epoxy primers. I am using the epoxy mostly because of the extended time in primer, with chances of getting rained on before paint. I agree with the suggestion of the 320, but you never mentioned if you are wiping the surface down with a prep product. I also learned from PPG that incompatibility of products will be the biggest downfall. Good luck, resand with 320, wipe with a wax and grease remover and give it another chance.

 

Several people have given the correct answer for the correcting the problem but the cause like in many cases can be one or several contributing factors. In this case the most obvious cause was the application of product beyond the recommended crosslink window. This window is affected by several things , air temperature, surface temperature, reducer and hardner choice. You really need to be familiar with the paint product line your using. Most paints are designed around a 72 degree working temp. But raising or lowering temperatures can produce significant changes in the working and drying times of the products. Did you know you can take catalyzed primer , sealer or clearcoat , seal the can , put it in the fridge and if the temp is lower than 45 it will not cure. Raising the surface temp to 130 degrees can cure most products within 15 minutes. As far as final cleaning before application of sealers and top coats. Prepsol is not the prefered cleaner. We use an alcohol based final cleaner that is part of the recommended procedures from our paint manufacturer.( Dupont 3909s or equivalent). Once a catalyized product cures there is no chemical bond between coats or products . You can see the sealer attached to the top coats as the paint is peeled off in the pictures as evidence of this occurring . The only bond that will exist is mechanical ( sanding ) and 600 is way to fine . 320 or 360 will be necessary. Always be extremely familiar and follow the product data sheets religously. Check the paint company's web site and look for the troubleshooting / problem pages. Most have picture documentation of the problem with the cause and repair recommendations .

Best of Luck!

Ain't painting fun !!!!!!