Adhesion problem perhaps?

S

Steves69LS3

Hello first let me state the specs. Gallon of white epoxy and activator purchased in October 2011. Used some at he time then in winter months stored in 65 degree basement until this past Sunday.
I sanded bare metal and existing epoxy with 180 DA. Only shot half of the door and forward edge of quarter so not a big deal to remove.

I cleaned with waterborne to the "T" as you would waited at least an hour in the sun mixed epoxy 1:1 tacked and sprayed a light first coat 15 min flash then a medium coat with another 15 min flash and finally a last medium to heavy coat just getting anything I missed. Metal temp was in the 70's. Today about 3 days later I went to do some filler work around the door edges and noticed that if I take my fingernail I can scrape the epoxy off. Not easily. Kinda like if you were taking the price tag off of a picture frame.

Now is this because maybe my hardener went bad?? It is a honey color. Don't remember color when I first bought it

Or is it still curing and give it some more time??

Thanks guys
 
Sounds like your ok.
The part you broke through after 24 hours or a few hours in sun, see if you notice it getting harder- you will.
 
thank you for assuring me guys. tomorrow i will put my infrared curing lamp on it for a while while i do my trucks brakes.
i will definitly post an update!! goodnite
 
Set the infrared about 2.5 feet away, metal temp should be 120 or less.
Also just setting overnight you will see a big difference as solvents escape.
 
another thing the surface felt soft but like i said before it wasnt too easy to scrape with my nail. hopefully it just needs more cure time. i shot my cowl panel a few weeks ago with the same batch of epoxy and hardener and it is solid so i think i can rule out the bad hardener theory
 
would you need it to fully harden before any body filler would be applied?
 
Rustbuster77;20356 said:
would you need it to fully harden before any body filler would be applied?
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No, next day is normally fine but if solvents are trapped, the filler can soften the epoxy and you will notice this if you break through, no harm done but everything is slowed down at that point.
 
Barryk;20358 said:
No, next day is normally fine but if solvents are trapped, the filler can soften the epoxy and you will notice this if you break through, no harm done but everything is slowed down at that point.
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This may not be the right place to post this but the cause and principal is the same as putting filler over solvents trapped in an epoxy and this is why i thought of it.
A fresh paint job, up to 90 days old, if you tape for stripes or what ever, you never leave the tape on more then a day. The paint can pull off, as the tape stops the solvent from escaping and will re-flow and cause the base to pull off the epoxy or sealer.

Yesterday a real good shop i have dealt with for about 17 years called and said he pulled tape off of two cars and the base came off and yet a 1/4 inch past the tape edge he could not scrape the base off, thought he had bad base.
First question was how long was the tape on? One car about a week and the other car three days and both jobs were about three weeks old before taping but had no days out in the sun yet.
I get a call like this about every six months and this guy is one of the best but he got tied up on other jobs and the tape jobs were in the other part of shop, so out of sight, out of mind.

Edit:
I just remembered the call about last Christmas on the other one, this was a good production shop I have known for about 10 years, they pained a blue base clear on a corvette all over and the painter was doing the white stripes in SS and painted just before closing up for a long weekend and because it was a last minute deal he left it taped up until they came back 3 or 4 days later, sure enough the base came of in spots with the tape.

Edit:
This is also why you NEVER wax a car before at LEAST 90 days.
Think about this, as thin as a new factory paint job is and depending on the factory, they bake 450-500 degrees for usually 60 minutes and yet they say don't wax for 90 days as they know the solvents are not out yet until so many days in the sun.
 
good news to report maybe? just cama back in and tried scraping that same area with my fingernail and it seemed a little harder than before therefore i set up my infrared curing lamp i couldnt get it 2-1/2 feet away but its at exactly 2 feet metal temp was 105degrees i will check again in an hour and post up
thanks for all that helped!!
 
ok just came back in. and checked that same area. i was able to scrape a 2in line with my nail pretty easily. also some other areas were soft. then i took my infrared thermometer and the metal was around 130 degrees im guessing it is too hot and after a cool down it will all harden up?? should i shut down the lamp now??
 
Barryk;20359 said:
This is also why you NEVER wax a car before at LEAST 90 days.
Think about this, as thin as a new factory paint job is and depending on the factory, they bake 450-500 degrees for usually 60 minutes and yet they say don't wax for 90 days as they know the solvents are not out yet until so many days in the sun.
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Wow! I was unaware that paint could even take those kinds of temperatures for that long. You would think it would just be ash on the other side :p
 
dbohemian;20402 said:
Wow! I was unaware that paint could even take those kinds of temperatures for that long. You would think it would just be ash on the other side :p
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I have often wondered about that myself, I'm sure over the last few years this may have changed due to energy costs and not real sure how the water base has changed the curing.
I know years back the normal clear with the blocked accelerator most were set not to kick at anything under 350, as the factory's get their clear with the iso mixed in.

I no longer have the connections to know.
 
After letting it cool I feathered out all of the scrapes I made and everything is fine I will try to post pics later
Thank you all again
 
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