Heres why i ask.I'm looking for a thick seam sealer like the factory used in the trunks,floors and firewalls. 3M urethane seam sealer is about $20 a tube. Home Depot sells PL Urethane roof and flashing sealant for $2 a tube. Its thick like the original stuff. Stays flexable when dry(kinda like winshield urethane),says its all urethane(no silicon)its also an adhesive as well as a sealer.So other than the 3M being paintable(not sure this other stuff isnt bit it doesnt say so i'll assume it isnt)It seams like the same stuff to me. I used it to seal up some floor seams on a budget job and it worked great. What do ya think.Is all urethane created equal. Just for comparision 3M windshield urethane is $20 a tube too.If it can seal a roof from weather why not a car? Whats the diff?

Well, sense you are there, pick up some large nuts to hold your wheels on, they are a lot cheaper. Don't stop there, get some paint thinner for your paint, and for that matter, get the paint!

I am not beating on you, but I wanted to make a point. You are restoring a 20ish thousand dollar car, just spend the 18 extra bucks and do it with something you KNOW is right.

I am not saying it isn't the same or extremly close product, I just don't see a need to be a "junior chemist" to save so little money when you are looking at THOUSANDS of dollars to restore a car.

And when you go to paint it and the automotive paint wont stick ...... :(

By the way, I dont remember where I got mine, but it was in a quart can, like a paint can, and certainly was not $20. Brushable seam sealer ... 3M I am pretty sure.

I was planning on the floor and firewall where it is not seen so im not worried about painting it.BTW i read the label and it is paintable. OK no need to flame me im asking a legit question.Chemically what is the difference.If you cant answer,keep the wise coments to yourself.The 3m stuff is not as thick as the original stuff. I guess because it has the 3M name on it and its expensive,that makes it right? :rolleyes: Bill the 3M brushable seam sealer is not urethane as far as i know.

The advice they are giving you is good and nobody is flaming you. The stuff may say paintable but that's most likely household paint, not automotive with reducer in it. Might work fine or it may react, outgas or ? later on. Maybe someone else has experimented and can step up and help out.

I use the 3M seam sealer and it works just like factory - if you use the right brush and thickness. One can does quite a bit and can be closed up for use later on.

I CERTAINLY am not "flaming you". I don't know chemically if they are the same or similar. Unless you get someone to works for 3M or a competitor in their lab, you are NOT going to get anything but guesses.

Your question is a good one, I just don't know anyway to tell you to forget about it other than what I said. If you don't know or couldn't find some guy who works IN 3M r&d or marketing dept to tell you they are exactly the same product you are taking a heck of a chance.

Now, if you want to do the research yourself, I have done it many times. Simply get an MSDS on both products. Check the batch numbers on both products, they may be the same. Of course you would have to get one home sealant and one auto sealant from the same batch, if they are both new on the shelf this is possible.

I have varified many of my "hunches" by looking at batch numbers. The MSDS can be fooling sometimes. Believe it or not there are componants they don't have to list for one reason or another. And not only that, the use of the product may require a different layout and information on the MSDS so looking at the exact same product with two different labels on the can may give you two differnt MSDS. But it is a good start.

Boom, we used the same "sealant" on a 59 Kharma Ghia about 2 months ago on the floor pan area prior to painting it. It hardened quite a bit after the two months but thus far have found no issues with paint adhesion. Time will tell if it will help keep the seams dry and clean. Good luck.

i have used the 3m in a tube im my shop and will never touch it again,it cracks,i have been using marhide brand in a can and am happy so far

Just out of curiosity, which of the 3M sealers did you have problems with?

I really like the 3M brushable seam sealer for many reasons. You can use it all unlike the tubes that tend to dry up in the tips, and it spreads easily and looks great. It isn't that expensive considering you get a quart.

Ed