Transtar 2k Epoxy Primer Problem

[79K10Step]

Looking for any Ideas here, 4 weeks ago stripped stepside bed down to bare metal. Then applied 3 coats of 2k epoxy primer. It has been cold and the primer won't cure finally warm enough to put out in the sun but still will not sand without gumming up the sandpaper. I let the guy at the shop mix the primer and hardner and fear he mixed like regular primer 4 parts paint to 1 part harder vs Epoxy Primer that is 1 to 1. Should I keep putting in the sun and wait or strip it off and start over? Very hard to sand out as my next phase was to put high build primer on before final paint and clear. Would wiping off top coat with acetone or lacquer thinner help??

 

[waterpirate]

I would give it 2 days in the sun for the " old college try " and then if it is still no joy, I would scrape some of the gummy $hit off the bed and go down to the shop and ask for some " splaining". Even in cold conditions that epoxy primer should have cured by now.
Eric

 

[CalSgt]

What @waterpirate said…

If it didn’t cure already I would bet you had bad catalyst, or improper mix. Is it still sticky? If so I’d just strip it off, why spend all the time and money building up from a poor foundation.

Epoxy is is a PIA to sand and will clog paper quickly compared to a urethane product. I use epoxy to seal the metal and topcoat with urethane high build while it’s still in the re-coat window just to avoid sanding epoxy.

 

[mxer147]

That sucks, nothing worse than doing that 2x. My dad was a bodyman and painter, never did a car for me ever until about 2 years before he passed we decided to paint my 88 Silverado shortbox. It didn’t need any bodywork except maybe a small ding filled here or there while we sanded down the blue sun faded paint. We even moved the box back so we could paint both sides between. So he sprayed the primer then an hour or so later he laid the first coat of white. He goes out to smoke a cigarette and I was looking at the first coat and it starts crackling. I go outside and mention it to him and he goes what? Go back inside and the paint was lifted. Ahhh, we can paint over that right? Nope it all has to come off, I almost cried and cursed the entire time sanding the paint and primer off again. He said he probably mixed the wrong reducer so the paint and primer weren’t compatible. That paint mixing room had all kinds of unmarked cans which was a good lesson for me when I mix plural components…use quality mixing cups, strainers and be 100% certain what you are mixing and the correct ratios.

But still, I hated doing it twice!

 

[79K10Step]

Thanks for the replies, left it out in the sun each day last week, it was in the 80's and still never cured. Could dig my finger nail in and finally pulled the plug. Got 5 gallons of lacquer thinner a bunch of rags and a new respirator. Coming off with effort but starting again...ugh

 

[fast 99]

Many paint brands have mixing formulas on the can and complete instructions sheets should be available. Yeah, too bad it's expensive and time consuming to start over.

 

[CalSgt]

Thanks for the replies, left it out in the sun each day last week, it was in the 80's and still never cured. Could dig my finger nail in and finally pulled the plug. Got 5 gallons of lacquer thinner a bunch of rags and a new respirator. Coming off with effort but starting again...ugh

Yeah, in 70+ heat that stuff should have catalyzed and hardened within a day even without being in the sun. You made the right decision to strip it off.

You said someone else sprayed it for you right? Was there any product left over? If so, the leftover should be 50/50 or even amounts if they mixed it at the right ratio.

Also, what was under the epoxy? Bare steel, or old paint or what?

 

[Doppleganger]

Yeah, in 70+ heat that stuff should have catalyzed and hardened within a day even without being in the sun. You made the right decision to strip it off.

You said someone else sprayed it for you right? Was there any product left over? If so, the leftover should be 50/50 or even amounts if they mixed it at the right ratio.

Also, what was under the epoxy? Bare steel, or old paint or what?

I think he said bare steel. Every time I've seen this stuff sprayed it flashed in 15 min or less.

 

[Grit dog]

I’m trying to figure out how you had it mixed at a paint shop and then diy painted it later.
And why would you catalyze all of it at once?

 

[79K10Step]

So my truck bed (cab is done) is at a body shop where I do all the grunt work sanding, grinding, welding, mechanical and the shop does painting, bondo etc. I do all the sanding/prep between coats. One of the young guys just out of body shop school mixed/sprayed the 2k epoxy primer after I had stripped to bare metal and put bondo on the ruff spots (pitting etc.). Knowing 2k epoxy needs 3-5 days to cure before I sanded it down for high build primer. (wanted the 2k to seal whole bed and the high build to make it smooth). The shop owner told me to try and put it in the sun to cure as he felt like the mix of hardener to 2k primer was wrong. I scuffed the top coat best I could so the sun could get deeper. Never cured now back to bare metal.