Dave's epoxy shop rules (please amend anyone)

F

flynams

I had a call from a guy who knows me and lurks on this forum and wants to use Shine's epoxy only highbuild technique. I explained MY shop rules on the epoxy subject and he thought I cleared up many questions that he had by a few simple rules. I never start a thread, but he talked me into it, so let's have some lively discussion, as I don't know everything, for sure

1. Never put anything over unscuffed epoxy after 48 hours except itself (this should open up some discussion, but I'm into overkill, and I have seen some quickly hardend stuff, (not SPI))...my thoughts here are to be on the safe side (we scuff most everything here to be safe)

2. If you're going to use epoxy as high build, don't EVER put something else over it after you have been blocking it for a period of time...DON"T FORGET WHAT YOU"RE USING, put at least one coat of epoxy on before using another material. Epoxy sticks to it self, but most of today's coatings have problems sticking to CURED epoxy. Epoxy is about the best thing to spray on anything bare and clean and scuffed, if you can't find a more appropriate material.

3. Don't rush the cure...wait to work it until it's workable.

4. Mix the epoxy ahead of time if you can, it is a must to let it set at least 1/2 hour if you reduce or thin it. We mix our epoxy ahead the night before, most always.

5. Use SPI epoxy
 
I like everything I see and great idea!!!!!

I would add, long flash times between coats, for some reason 4 hours, just sticks in my mind as the perfect flash time.

I like to mix the batch in morning and use in afternoon, 2-6 hours induction, just seems to make a difference.

Everyone do add any ideas or what you have found works best.
 
I have seen unsatisfactory adhesion of body filler on unscuffed epoxy starting in the 72 hour range, depending on conditions. A light 150 and red scotch pad to break the shine works wonders, and I don't believe the surface needs to be recoated to apply filler to a sanded epoxy surface unless it's been a long time.
 
crashtech;3556 said:
I have seen unsatisfactory adhesion of body filler on unscuffed epoxy starting in the 72 hour range, depending on conditions. A light 150 and red scotch pad to break the shine works wonders, and I don't believe the surface needs to be recoated to apply filler to a sanded epoxy surface unless it's been a long time.
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Jon,
Interesting, would the epoxy have been reduced? That does effect open coat, just curious as I will run some tests, if it was not reduced.
Thanks.
 
I've been using un-reduced for under filler apps. At first I thought it was surface contamination until it kept happening. Our shop is pretty free of airborne junk. The filler is Marson Platinum. Letting the filler cure longer does not help, only scuffing off the shine works for us right now. For sure after 4 days it's a no-go for us.

It's not that big a deal, but it is in keeping with rule #1 of the OP, so I thought I'd mention it.
 
Thanks Jon for clarification, good to know stuff like this, so we have a testing point.
 
well i guess i can talk about epoxy only here without getting my butt flamed. i treat the epoxy just like i would gel coat. shoot it wet and heavy. block to satisfaction then start a finish. first thing on refinish is a coat of epoxy sealer.
 
I have a question that goes along with the other thread about epoxy and temp. I know that you're supposed to have the metal and the epoxy at a certain temp, but, what if I'm doing something as involved as what Rusty does and it will sit in epoxy for say a few months. then I go back and sand that down then reply epoxy or even high build, will that be ok? I'm in north Fl and right now it's getting into freezing temps and I want to sand blast and start working on my car.
Also can after I sandblast can I just clean the metal with W&G remover then spray or should I sand with 80 or 180?
 
crashtech;3560 said:
I've been using un-reduced for under filler apps. At first I thought it was surface contamination until it kept happening. Our shop is pretty free of airborne junk. The filler is Marson Platinum. Letting the filler cure longer does not help, only scuffing off the shine works for us right now. For sure after 4 days it's a no-go for us.

It's not that big a deal, but it is in keeping with rule #1 of the OP, so I thought I'd mention it.
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If you can scratch the epoxy with your fingernail you won't need to scuff it. 2-3 days never a problem but I check it after that or just scuff it to be sure-never ever had any adhesion problems. I use Evercoat fillers.
 
Thank you for the advice, Bob. I will try the fingernail test. I was actually surprised to find that in my case, the window for filler is closing well prior to 7 days even in fairly cool temperatures.
 
Trying to come up with a "good" answer here myself.
I'm in a "mess" right now with the dually roof and have been on & off it as time allows.
After blasting to bare,clean and epoxy,I blocked with 150 to SEE where I'm at.
Did everybody and their kids stomp on top of this thing??? Christ,I got so much "stuff" to deal with and an inside complete liner and no access from the underside and no,I'm not cutting holes in the liner as I've already painted the interior and don't want to F' it up,I'm just about ready to QUIT,but I can't,So, I'm making the best of what I can with studs and shrinking and wtf ever I can to deal with it. About there but still have some work to do.
However,I blocked it to find the typical "filler" places and leave them shiny until I get "around to them" and the tough areas are being hammerd out so to speak.After 2 solid coats of unreduced SPI epoxy,I find it as tough as nails to get back to bare for studs or such and even working the shrinking disk on it hardly breaks thru in areas I've not sanded down.
I will recoat all the bare with unreduced epoxy and apply filler within 24-48 hrs with no sanding.I always give the epoxy 24 before ANYTHING.Other areas that have been on for the last YEAR will be sanded with 150 before applying skim coats on all the "crap".I've applied regular E'coat Rage on some of the cab areas that were welded shut or repaired with the 150 treatment over the original epoxy and it's stuck great and been roughed out with no issues at all.
You all can do as you see fit,but IMO, I won't touch epoxy until at LEAST the next day.Unless of course,it happens to be 98 and IT sand OK.
Which brings me to MY point I guess.
IF it sands good,it's good to go.
BTW Bob,I ain't got any fingernails left anymore,Hehehe.
Still got my hair though so it's not "that" bad....Yet.....
 
This is the exact confusion that made our rule in the shop...unless you're in the finish painting mode, EVERYTHING gets sanded or scuffed...doesn't take that long, and it STOPS the possibility of, well, er, um, uh, you know....
 
Mike K;3769 said:
BTW Bob,I ain't got any fingernails left anymore,Hehehe.
Still got my hair though so it's not "that" bad....Yet.....
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I know all about sanding fingernails off, seems this work is 90% sanding most of the time. My hair is getting thinner by the minute lately.

The epoxy recoat window can fluctuate depending on quite a few vairables, JMO-application thickness and temps are the two that seem to affect it the most. I've done successful filler applications after one hour of applying epoxy but this is when only one thin coat of epoxy was used-same as applying a sealer coat of epoxy before paint and you know the epoxy is fragile at this stage in the cure. Best case scenerio is one or two wet coats of epoxy over your bare metal and an overnight cure before any filler or urethane primers are applied-JMO I wouldn't put anything over cured epoxy that hasn't been scuffed-remember epoxy relies on texture for adhesion. I like how this forum gets into the nitty-gritty on every topic.
 
Thank you Bob, perfect! Even air pressure has an effect, as Well as temperature and reducer speed and or the amount of reducer and right down to the tip size can change curing.
 
thread going on over at chevelles.com bodyshop about using epoxy under filler referencing this article

http://www.autobodystore.com/filler_&_epoxy.shtml

Article is full of flaws and not enough tests..but it is articles like this that make guys automatic professionals at epoxy. Why are some guys completely against epoxy? It seems the ones that are against it, have tried it once or twice and they weren't pleased. But they wont admit if they applied it in the right manner or not....we all know every epoxy is different and they ALL have varying dry times for the application of filler. It seems that most of the confusion is about sanding or not sanding. Most "failures" that i read about are from non-sanding applications. IMO there are just too many variables to consider when applying filler over unsanded epoxy within the window. I always scuff...even if it is just a red scotchbrite the very next day. Never seen a problem as of yet with using epoxy under filler. With scuffing you are getting twice the adhesion, imo...chemical and mechanical.
 
He did that test years ago and bottom line is production painters don't like epoxy, it is just to slow.

1 coat of epoxy.
Filler applied in 30 minutes.
Does he know epoxy does not gain adhesion for days.
Test he did, he did it to fail, that is what he wanted.
Maybe he needs a better epoxy?

Best thing he can do, is not use epoxy and I'm sure he doesn't.
 
I remember the hoopla that test caused. That test really sucks ass because it portrays his miserable luck rushing DPLF and makes it sound like the test is valid for the basic filler over epoxy proceedure. Had he done it with PPG's old DP version he may have had better luck but not by much because the 30 minute cure time is way to short to have real test results and it was way to soon to do the destruction testing. The tech sheets for DPLF were written at the bare minimum recoat time to increase production speed-I'm sure they didn't think someone would actually do a torture test thinking everything was at full cure-LOL And check out the statement at the bottom of the article:

Serge is a regular contributor to the Autobodystore.com Forum and has had extensive experience with both body repairs and painting. His results should be recognized as a reflection of this experience and his ability to evaluate the materials and process he used. Different materials and processes could result in different or similar results.

I wouldn't let that guy work on my plow truck if he thinks that was a valid test.


If you do a test with properly sanded bare metal that has been cleaned properly, apply two coats of SPI epoxy and allow it to cure overnight before applying filler, then allow it to cure one - two weeks and try the bend test..........what you'll find is the adhesion is so strong the filler will flex far greater before yielding and then it doesn't shatter in large chunks but instead it micro cracks evenly. Compared to a filler over bare metal test the results are obvious. Long term results are way better especially for corrosion resistance.
 
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