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Spi epoxy, then poly. What’s your opinion?

#1
Restoring a 65 Chevy C-10. Entire vehicle dustless blasted ( hold-tite wash down, was done 3 years ago) . Have been working the body for the time after that, getting real close to done. Almost ready for primer. Body has been currently bodyworked over bare steel, and sitting at 80 grit.

I used Spi on a Camaro years ago. Same process, epoxy over filler, then spi 2k, epoxy, then spi finish. (Spoke with Barry at length on that one) .. love the products.

I have already purchased epoxy, been using in all the inner panels, and where panel replacement has occurred.

Really wanting to poly this vehicle. I have however never used poly. Looking at slick sand or G2 I think...

Long post sorry... more info the better....

Question is I can “rent” a bake booth for the weekend. Tired of painting in the garage.

Is baking epoxy recommended, should I just poly over filler and steel?
I’m thinking to epoxy first, then poly, then epoxy seal and finish. Obviously with lots of poly blocking in between. Can I even do epoxy, and poly in 2-3 days?? Should I bake?
Thoughts? Is there a better process?


Thanks in advance. Long time reader, first time poster..
 

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Chris_Hamilton

Trying to be the best me, I can be
#3
Epoxy is always the "correct" choice. :) Spraying Epoxy, make sure temps are 65-70 both in the air, on the metal and the epoxy as well. This is very important as SPI epoxy needs to be at least 65 degrees (70 would be better) for at least 24 hours straight. Setting it out a full day in the sun helps a lot too. I would consider that almost mandatory especially if I was applying poly primer over the epoxy. Give it a minimum of 48 hours before applying the poly primer over the epoxy. This is very important.
As for your question about baking it, I wouldn't do it. If you did you would want to keep it at 120 degrees, no warmer than that. But epoxy cures differently than urethanes. Epoxies need time more than intense heat. Even if you baked it you would still need to observe the above times. Otherwise you risk the epoxy not curing correctly and having to re-do everything. Just keep in mind 24 hours @65-70 degrees. Put it in the sun for a full day if possible. 48 hours minimum before applying Polyester primer.

Just a note about poly primer. It fills good, sometimes too good. :) Don't pound it on because it builds a lot. Two coats, block, then re-apply if neccesary. That'll help from building up too much around edges, opening etc. You'll want to use a fairly coarse paper for your first round of blocking with it because of how it builds.
 
#11
Personally, I use the G2 but that is all I have ever tried so can't say anything about Slicksand.

You will need some Acetone on hand for thinning and easy clean up.

If you haven't used a polyester primer before pay very close attention to set up time. This is like spray on body filler in that it is a chemical reaction that makes it cure. There is no flash time or grace period with this stuff and if you have some in your spray gun when it kicks your gun will be seriously plugged up.
 
#12
I had to install a used quarter panel on this '65 Buick Convertible. It had a lot of problems with it so I opted for the polyester primer route.
Quarter Skin Fit check 1.JPG

After some welding, hammer and dolly work, a 3 coats of G2 buff color:
LH Quarter - Poly Primer.JPG
 
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