There are SO MANY different kinds of stuff to use for sealing seems and leaks in an Airstream. The Original stuff used in manufacturing was called Vulkem 116, and it’s still available (either as Vulkem 116 or TremPro 626), but the original Vulkem company was bought out by TremPro. Vulkem 116 is gritty and will stick to EVERYTHING. It also takes FOREVER to cure (so cleanup rags will remain gooey for days).
There are a LOT of varying opinions about what’s best to use for what, so I am posting what I’ve learned from researching and using the various products.
The original factory “caulk” is Vulkem 116 (gray), and is now marketed as either Vulkem 116 (the original name) or TremPro 626. It’s a texturized (gritty, like it contains sand) poly that takes FOREVER to cure (which can be a good thing when you’re talking Airstream). The “official” cure rate is 48-72 hours, but it can take a lot longer than that, depending on the actual environmental conditions. Vulkem 116 also cures fairly hard when completely cured, and is thus best for exterior panel seals, a/c installation, setting window frames, etc.
Vulkem 631 is Vulkem 116 but in different colors.
TrempPro 636 (gray) has a slow cure rate (4 hours), has more solvent (better for exterior applications), and is non-textured (smooth).
TremPro 635 (gray) has a faster cure time (90 minutes), and is a low VOC/solvent free silane terminate poly. So far, this stuff is my favorite, especially for things on the inside. If you’re doing Airstream restoration, I recommend having at least two tubes of this stuff around, as it’s not available from a lot of places and often takes a while to ship and arrive.
Sikaflex 221 (black) has a fast cure time (60 min.), but seems to require a cleaner surface for adhesions, whereas the Vulkem and TremPro will stick to just about anything. Some people think it looks better (smoother, more like typical caulk) and is a little easier to work with (doesn’t stick to everything). It’s typically used for things like interior vent, window, latch, etc., applications.
The products above are for more “construction” type applications. There are several products like that can be used to seal tiny cracks and leaks around rivets, etc. These sealers actually wick into the cracks and crevices, whereas the products above are more for adhesion and filling larger gaps and holes.
Acryl-R seems to be a lot of people’s favorite for a wicking sealant, but it takes a special applicator. The “go to” product for sealing on the road seems to be Captain Tolley’s Creeping Crack Cure.
Parbond from Parr is a sort of “in between” product that comes in a “roll-up” tube (like toothpaste) instead of a caulking tube. It is silver, so shows less than something like Sikaflex on exterior applications. This is a good product to have with you on the road when you don’t want to store a caulking gun and larger amounts of sealant.
Butyl Putty Tape is what you need to use when setting windows, a/c, vents, and other things that have a collar and set in to a hole in your Airstream exterior. This soft, flexible product is like a roll of flat Silly-Puddy that will seal two surfaces together and keep them that way.
Walbernizer specifically formulated for Airstream coated aluminum surface.