Wrong mix with epoxy

bill3337

bill3337

Member
Ok, it's embarrassing enough to have to ask this question, and yes, I am an amateur home painter doing only my own car. I mixed up some epoxy yesterday
(Sherwin Williams E2B 931 black) and mixed it incorrectly. Unfortunately, I didn't realize it until after I had sprayed the body and doors. The mix should have been 4 parts epoxy, 1 part hardener and 1 part reducer, however, I used 8 parts epoxy, 1 part hardener and 1 part reducer. It sprayed nice, seemed to set up properly and sands ok, doesn't peel or show signs of failure when sanding, but I'm concerned with the wrong mix, it may cause problems down the road. If I have to take it off I will, but not looking forward to it. I haven't been able to contact anyone at Sherwin so far and I know Barry sometimes will answer questions about general problems, so I'm trying here. Thanks, Bill
 
I know what I would do, and that would be to take it all off. But if you are willing to take great risks with the ultimate outcome of your paint job, one simple test would be to check solvent resistance of the coating after a couple weeks. If you can get the primer to start coming off onto a towel soaked with reducer, you should consider the application a failure.
 
Thanks for the reply. The coating will not rub off or ball up with reducer or lacquer thinner after the first 24 hours, even after sanding the surface. Is it more likely to fail after more time?
 
I don't know if it will be OK, but generally good solvent resistance indicates that the required cross-linking reactions are taking place.
 
If it was mine, I could give you an honest answer but I don't know the resin or amines S&W is using.

Sad part here is the jobber will be of no help and not sure they can give you a tech number, where you are talking to someone that is not reading from a standard note pad of answers.

My BEST GUESS, is your OK, because you can wipe it with solvent and you seem to have adhesion, most epoxies in automotive cure similar to body filler, if it was mine i would tell you to let it set 2 days to a week or a day or two outside, then test if OK, sand re-coatcoat with proper mix.

Of course the proper answer is --Strip.

Also feel free to call.
 
if it were anything other than shrink and wrinkle i would most likely go on with it but in this case i would remove as much as possible. try wet sanding with 180 or 80 to get it off.
 
shine;26275 said:
if it were anything other than shrink and wrinkle i would most likely go on with it but in this case i would remove as much as possible. try wet sanding with 180 or 80 to get it off.
Click to expand...

HA Shine used the Shrink and Wrinkle Term!love it.

i would think u are okay if Reducer or Thinner wont take it off.

Travis
 
kicked does not necessarily mean adhesion. i would do some serious 2 in tape testing but in the long run you are risking a complete failure. not something i care to do. i know this car and it deserves the very best. if i could i would send bill some spi !
 
Barry, Shine, Crashtech and Hotbo, thanks for your opinions. I'd love to take the car outside for a week in the sun, unfortunately it's too big to fit in my suitcase to take to Maui with me........as we won't see sun in this part of the great north until June........ I'm going to try to get in touch with a chemist at Sherwin tomorrow, but I have sanded the bulk of it off on the main body panels and will try to get virtually all of it on the main panels by hand. The tough parts are the firewall and inside rain gutters and interior of trunk weather strip channels etc and I don't want to use any chemicals to strip it. Even when I've sanded the panels to the point where I've gone through slightly, lacquer thinner or reducer still won't affect it by rubbing with a towel soaked in it. I'm reluctant to let a soaked towel sit on it for any length of time in case it soaks in and causes problems in the future. Barry, one more question for you....if I was to switch to SPI epoxy, which I think I can bring in through a rep here (I don't think anyone stocks it here in Victoria, B.C.), is it compatible with the Sherwin products if I was to use SW base/clear over? and would it be compatible with the SW epoxy that's on it? Thanks again, Bill

I'll let it sit a few days to a week then try to do the final sanding by hand. Right now 80 grit on a D/A sands it normally, doesn't gum up the paper or anything, but if I try hand sanding with a long board and 120 it plugs up the paper within a few strokes.
 
I can answer one part of that question, I was a Sherwin shop for five years and sprayed many S-W products over SPI epoxy, never a negative reaction.

Honestly, I've had more wrinking problems with Standox, I never had S-W base wrinkle anything, ever, though it definitely shrinks at higher film builds.
 
I talked to the Sherwin Rep at their head office today and based on my descriptions (sands easily, doesn't ball up or peel with thinners etc) he thinks it's ok.........however, I have sanded about 90% off now, so it's just a thin film at its thickest and gone in some. As a final test I'm going to spray one panel with the same epoxy again to see if I get any lifting or bullseyes as the epoxy cures. If the adhesion is compromised I expect it will lift around the feathered out areas. If it doesn't lift, I'll hand block it once more to get everything I can off, then start over. Fortunately it's just the body and doors, not the fenders, deck lid and hood etc.

Barry, a long time ago you gave me the name of an SPI rep in Victoria, but I've lost track of that. Could you give me that once more please? and thanks for your help.

Happy New Year everyone! Bill
 
Bill,
Sounds like you got some good news but the respray won't tell you anything because epoxy is air tight.
Best tests, is a razor scraper and rubbing a spot with urethane reducer or lacquer thinner.
If you have adhesion and it does not wash off with 10-15 rubs in a 6 inch area with thinner or reducer, I would sand and re-coat.
I will get Doug's number Wed.
 
Bill, I can't comment on the chemistry-but with the group you got helping your covered.

Your "embarrassing" comment made me smile. I think mixing components wrong falls in two categories; those that have, those that will. I can personally tell you SPI Hot Rod Black sprays pretty flat when mixed only with reducer... Mine was the underside of a fender, sprayed over epoxy, so I didn't admit my screw up. Good Luck
 
Barry I continue to thank you for your advice. I have sanded the epoxy completely, totally off in some areas and just a thin film in others and if I do recoat it, I will sand it again thoroughly with a hand long board and 120 grit. I have tried the rubbing test. I used laquer thinner for a couple tests and reducer for the other couple and it didn't get any transfer or peeling or balling. I also tried the scraping test and couldn't get it to lift, so I think it's ok, but will continue to remove everything I can from the exposed big panels. I thought I'd respray one door with epoxy after the thorough sanding and see what I get. Doug is your Canadian Rep? Thanks again.........and Shine, thanks for your comment on the metal work, I could have looked at it in bare metal forever...........almost......lol.
 
Bill,
Got all my SPI product through Doug Kennedy. Great service and nice guy.
519-437-9193
In Ontario but shipping was cheap and fast.
Hope this helps.
Dean
 
Current update. I let the epoxy sit for 6 days, then sanded the bulk off (about 75% of the areas have no epoxy left). I did one door as a test. Where the blocked bondo skim coat is exposed, with all epoxy removed I got these microscopic type pinholes again in the first coat of epoxy. The skim coat is Evercoat Rage Extreme and didn't appear to have any pinholes. I don't think they were actual pinholes in the bondo, but could be maybe. The epoxy sat for an hour or more to cure, everything looks good, no signs of bullseye's or lifting anywhere, just these damn pinholes. These showed up within 30 seconds of spraying (maybe less) the first coat, so it's not solvent evaporating from the first coat. The pinholes are tiny and not like fisheyes, they're not really like a crater, they're just tiny holes. Could I be spraying too close maybe? I'm using an HVLP gun with 22 lbs pressure at the gun with the trigger pulled and have 120 lbs at the compressor. I have two water separators in the line, plus one of those toilet roll type filters, with the proper cartridge. I'm assuming and maybe wrongly, that the high build will take care of these pinholes. I could fill them with some U Pol two part dolphin glaze before hibuilding.....any thoughts? Thanks, Bill
 
Welcome to the wonderful world of lightweight fillers. What you are seeing are sometimes called "micropinholes," a final skim coat with some kind of polyester glazing putty before primer usually eliminates most of them.

You can just wait a day or two and then just fill those tiny holes with polyester putty right over the epoxy, no sanding needed. I like to scrape the spreader over the surface and try to leave the putty only in the holes so the straightness of the surface is not affected.
 
I put my regular glasses on today (not my shop glasses :eek-new:) and had a real close look look at the skim coat and that's where the pinholes are originating. They are almost microscopic, but they are there, so I will epoxy everything then glaze the pinholes. Everything else looks good, and it looks like my incorrect mix on the first coat didn't do any harm, but I have sanded 90% off just in case. Thanks for your help and advice. Bill
 
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