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which seam sealer??? HELP

I have a 67 Chevelle I am working on. Lots of new metal. Currently I am about ready to epoxy the underside of the floor and trunk pan as
well as the wheel tubs. I plan to shoot SPI epoxy, seam seal, then shoot Upol Raptor Liner over it all.

My question is which seam sealer should I use? 1K or 2K, brand, etc??

I have never done this and I want it to come out nice, not trying to match original factory ways either...

There are so many brands and types to choose from. I need a quality seam sealer that is fairly forgiving for a first timer....

Also when sealing how do you seal say a panel to panel where the gap is at the end of both. My trunk drop off and lower qtr panel flange
is spot welded but both of these end basically parallel to each other so to speak.


New Member
Hope you don't mind me hijacking but it's relevant and it makes sense rather than starting a new thread.

Any thoughts on the Eastwood seam sealers? I have read good things about them and they are a bit more reasonably priced.

Regarding the use of 2k products vs 1k, is the crack and pull away comment based upon experience or something you read? I only ask because I have read that same thing in a lot of places yet all of the name brands including 3M and Lord insist their 1k products don't shrink or crack.

Some of what I will be sealing is on the under side of my floor pan so I really cant afford cracking. The point is to seal the seams/overlapping panels that the factory didn't so I can prevent the seam rust I am repairing.

Last question, will SPI epoxy work over any of the seam sealers mentioned including Eastwood.



Trying to be the best me, I can be
1k will always shrink somewhat as the solvents in it evaporate. How much is usually dependant on how thickly it's applied. It is nowhere near as tough as 2 part epoxy based seam sealer either. 2 part epoxy type seam sealer is so superior to 1 part that it is not even comparable. Cures in 10-15 minutes compared to sometimes days for conventional seam sealer. And yes my opinion is based on experience, 25+ years of it. This forum is somewhat different than most as most of the frequent posters are real profesional's, who give advice based on experience not repeating something they read on another forum.

As for Eastwood branded stuff, I would stay away. Use Profesional products intended for use by Pro's. Lord Fusor, Evercoat, SEM all make good 2 part seam sealers. Yes you can spray it over any seam sealer. 2 part type seam sealer can go directly over bare metal. 1 part needs to be primed. If not it will lose adhesion fairly quickly. What would be better is to epoxy any bare metal then use the 2 part on your seams and re-prime after that. Will make your seam sealer that much more bullet proof.
I would not use Eastwood anything. Be careful that you don’t trap moisture by sealing areas the factory did not seal. If you trap moisture it will rust for sure...
My big issue at this point is along with the cost of the 2k sealers those damn applicator guns are so overpriced. I mean, $100 for a caulking gun...

Then I came across this gun. $38!! 81pikEGfZoL._SL1500_.jpg

I'm thinking this with some of the 3M 2k heavy body sealer, 08308, for the underside and some 3m brushable for the inside. It seems to me that the regular 2k stuff that is self-leveling wouldn't be the way to go on the underside. If I put it on too thick it might drip.

Any thoughts on the SEM sealers? They have a 2k heavy body sealer I could use for the external stuff and they have some reasonably priced 1k stuff I would use inside.

Whats the diff between the heavy body stuff and the regular? Is it much harder to work with? Is it better for areas that require a thick application?
I've tried the two part SEM and Norton, both in self leveling version, and found the Norton 97121 to be a smoother finish. The SEM seemed more of a pain to get it to flow out nicely..

Never having used these products before I'm making assumption about the self-leveling that maybe I shouldn't. Are they suitable for vertical seams or horizontal seams that are upside down like on a floor pan? I'm assuming they may run so I should use a non-self-leveling sealer.
Correct, the self leveling would be too fluid on vertical or upside-down surfaces. My post above was more to show I experienced a difference between brands in how the sealer went on...
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LOL. I gathered that and that is good info for my future reference. Thanks. I was just looking for confirmation on my assumptions, which you have provide. Thanks for that as well.

What are your preferred sealers when not needed something self-leveling? What do you like to use under your floor pans?
If you are planning to seam seal your floor pan pinch welds from below you will trap moisture and actually cause rust. Seal your floors from the top and leave the bottom open to allow moisture to drain....