2005 Ranger Edge. Had some rust bubbling through the paint at the bottom of the door jam, I was worried it was already a disaster, been meaning to get to it, bought 10 pounds of Black Beauty on Amazon, I have a siphon sandblaster, sandblasted it today, as I was sandblasting it, I don’t know what it’s called, “caulk“, was revealed under the paint, I wire wheel it all out because there was rust under it, already ordered a small kit of POR-15, does anybody know what that “caulk“ is, what’s it called, who sells it, where I can buy it? I am guessing it is some kind of urethane product. I’d like to apply POR-15 (strictly according to the instructions) then apply the caulk, then topcoat it. I’m not gonna be able to get in behind that gap/hole to paint the interior with POR 15, that sucks. I’m gonna try to get in from behind and spray it with Fluid Film after I’m done and everything is thoroughly dried.

 

That is known as "seam sealer"

There are various versions of it, so I cannot accurately recommend which one to use. However, any body shop should be able to either recommend the right product, or sell it to you.

Generally, it comes in a tube like caulk and is applied in the same manner

 

Thanks. I didn’t know what to put in Google as a search term. I was afraid the stuff was industrial and wouldn’t show up as any kind of consumer item. I did try it anyhow Google and I did manage to find some (actually so many of the choice was bewildering!) for sale on Amazon and it specifically says “this item is not for sale for consumer use, only for professional blah blah whatever use”. I didn’t think I’d be able to buy the real deal. Years ago I went to a place that supplies body shops and I bought some urethane paint that I assume is really kind of not for sale to consumers because you can poison in your liver. The stuff was advertised on Amazon as

“3M”, doesn’t look like 3M but on the back of the label it does say 3M.