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Discussion Starter · #1 ·
What's a good brand seam sealer ? I know anything that is made today is probably better than the 30 year old stuff I scraped off.All the auto and paint places here have a different type Pro form,Ap,UAP brand ......I would like it in a tube as I want to make a nice sealer joint/line where my floor pans meet the frame connectors.This will be on the bottom of the car painted but I want it to stay there forever.Is one any better than the other?Some are made to take some flexing where others recommend against it.I would think that the one that takes the flexing would be a better sealer .I would also like to use it on the top side along the floor seams .I believe that I will be able to brush it along with a stiff brush after I squeeze it out . Any info or input would be appreciated!
Thanks!
 

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here's a neat trick with Fast and Firm......

want to work it really really smooth after it is applied...

wet your finger tip with just a tiny bit of urathane reducer....

the caulk will feather out very nicely....you can make a panel seam invisible
 

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All of those solvent type seam sealers are junk, they shrink, crack, and dry out with age and have spelled death for many of the cars produced in the 60's and 70's.

Do yourself a favor and buy a urethane seam sealer, there are many available in a caulking tube for easy application. 3M's Ultrapro MSP is very brushable and Fusor's is also a good product. Some are packaged in a sausage like container that gets installed in a special appliaction gun but you really don't need the gun, I have a gun and they do work good but you can get by with just poking a small hole in the tube and squeezing it out like toothpaste. Sealers should be applied over a quality primer for best corrosion resistance, and for best results prime or seal before painting. The MSP can be primed, sealed, or painted while still wet which saves time.

Throw the solvent type sealers away. I can post photos of what they look like after just a few years of shrinkage as I've got a project in the shop right now with fast and firm from the previous bodyman that's actually got cracks so bad that some are 1/16" wide and the stuff is brittle it's so hard.

A good urethane sealer will outlast you and I and the next generation. Bob
 

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fast n firm is a good toolable product. We use it, but only on non-exterior surfaces (floors ect.) It makes a huge difference, how long it has to dry, before it is coated. It has to release its solvents, before you put more on top of them. We use no seam sealer on exterior panels.
Dave Tallant
 

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wildman1932 said:
fast n firm is a good toolable product. We use it, but only on non-exterior surfaces (floors ect.) It makes a huge difference, how long it has to dry, before it is coated. It has to release its solvents, before you put more on top of them. We use no seam sealer on exterior panels.
Dave Tallant
Dave, do yourself a favor and prove it to yourself, lay a bead of that sealer on something and let it set for a few months and see just how shrunk and brittle it gets, after a few years it'll shrink so bad that cracks will form and it will split and somethimes shrink to the point that adhesion is gone. Throw the test piece in the sun for awhile and you'll see the deterioration accelerate. Have you ever stripped a 60's or 70's era car where the sealer has shrunk, cracked, and held moisture for rust to form below?-fast and firm is the same technology-JUNK! Move on to urethane and don't look back, some of the two part urethane and epoxy sealers are also very good products-light years ahead qualitywise over any solvent based sealer in a tube or can.
 

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Fast n Firm has caused me some major headaches and if I had not already repaired the areas I could show you exactly what can happen in a couple of years. I know now that Urethane is the way to go, wish I had of known before.
 

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As I said, we use the better two part SEM, on exterior work. The fast-n-frim we use because it is toolable. We can wet with solvent, and smooth it out. We have been using this for a long time. It has two advantages. First is costs , the second is toolability. I understand, there are better ways to do everything. For about 6 years this has worked well for what we are doing. Sealing cracks on floor boards. If we start having any problems, we will change in a heart beat.
It is a two edged sword, trying to keep costs down for the customer, (product and labor ) and quality. We want and need our work to hold up for a long time. We have cars out there that were painted 20 years ago, and still look great.
The other thing to consider, we only seam seal over epoxy or primer. Very thin, it hides the seam lines.
Dave Tallant Hot Rods KC Mo
 

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I prefer the duramix sealers. Their control flow is very toolable and most of the time you dont need to tool it. I havent used a solvent based seam sealer for about for about 10yrs...Eric
 

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Discussion Starter · #14 ·
Sorry if this is a stupid question! Is SEM the name brand like 3m or does it stand for something else like synthetic elastic membranes ?. Just wondering as there didn't seem :D to be much of a choice when I was looking the other day.From what I have gatherd they were all the fast firm type.I want to know exactly what I'm asking for/talking about.
Thanks!
 
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