Newbie question

[smallbigblock]

What is the best seam sealer to use on bare metal.  Most of the one's people talk a lot about say to apply over primer (not etch primer).

I'm just getting to the point were I'm applying raptor-liner to the mini-tubs and it says to use a self etch primer first.  Well I can't put seam sealer over that so I thought I would try to put seam sealer down then the etch primer then the raptor.

What seam sealer?

[sunsetdart]

Most body shop supply places sell seam sealer. Eastwood also sells some different kinds as well. I used a brand I got at a local body shop supply, went over bare metal. Most all sealers can be painted over too.

[smallbigblock]

I know a lot of people like the 3M products and I wanted to use them but they recommend using over primer.

what brands are good over bare metal??

[CARS]

Why not just prime it first?  I always epoxy prime all of my bare metal, seam seal, then after waiting the correct amount of time, epoxy again.  Most epoxy primers give you a 3 to 5 day "window" before you have to scuff it for paint.  That gives you the time to take your time to get everything right. 

I use the Upol Raptor liner over epoxy primer all the time.  They just don't want you to apply the liner over bare metal.  Any properly prepped substrate will do even rust converters according to Eastwood.  (not too sure about that thought)

[Duster440]

There are basically 3 types of seam sealers: 2 part that require a special gun to dispense, 1 part that you can use a caulk gun (3M makes some like this), and 1 part in a can you brush on.

I used all three types on my project. The two part (catalyzed) is the toughest. I used some 3M in a caulk tube on my trunk floor seams. It eventually did shrink and crack. The brushable kind has it's place and works well.

The reason they suggest you apply it over primed metal is so that if the sealer fails at some point in time, you won't have bare metal exposed that will rust. However, it will stick to metal, primed or not. As suggested, it would be a good idea to hit bare metal seams with some epoxy primer first.

[CARS]

I looked at the instruction sheet for the heck of it and I think I figured it out.  U-pol want you to use Acid #8 etching primer because they manufacture it!  (it is a good spot primer though)

U-pols acid #8 and any other rattle can primer is a 1K product meaning that it doesn't have a seperate catylist.  (I have recently seen some 2K rattle cans but they require you to pull a pin and the two components mix together when you shake it.  This means it is a one shot deal and I think it was over $20.00)  Since it is really NOT a etching primer by definition I don't think I would worry too much about using seam sealer over the #8.  I would never say to apply seam sealer over a 2K etching primer though.


I used a can of Rustoleum "For Bare Metal) primer on a couple spots on a bedliner job once and the Raptor liner lifted.  Ever sence then, it is catalized primers all the time. 

[smallbigblock]

Thanks for the input I think I'll go ahead and use thier "Acid#8" (already bought it) then seal with "3M fast and firm" (already bought it)  before using the raptor liner.  I just want to do it right the first time but its hard to make decisions when I know so little.

[CARS]

Just be sure to follow the flash time directions on all the products.  Rushing things is the #1 cause of failures.

[smallbigblock]

Thanks for your help