I have a boat. Sealants are well researched in the boating community. That written there is still a lot of uniformed and incorrect opinion "shared" in boating forums and blogs on the internet.
It is important to understand which sealant/adhesive (including tapes like VHB or Butyl) to use for various materials and combinations of materials if you want the joint or whatever to last and not fail or leak. This is why, beyond competition, there are so many sealant/adhesive and even VHB tape choices. There are many different applications and materials that are best accomplished with sealants/adhesives/tapes formulated for those applications and materials.
For instance never use a polyurethane with Acrylic or Polycarbonate materials. The polyurethane attacks and damages the plastic. Similarly with acetic based Silicone caulks. There are sealants/adhesives (mostly special or hybrid Silicone formulations) such as Dowsil 795, GE SSG 4000 and Sikaflex 295 (with 209 primer) specifically formulated to work with plastics without causing damage to the plastics. I and many others have researched the sealants/adhesives to use with plastics extensively. However, the reason why these are the best adhesive/sealants for plastics and even which is preferred in a given application requires more detail than is appropriate for this comment space.
The bottom line is that sealant/adhesive selection is important relative to the materials you are using it with and the application you are using it for and therefore there is not a best one (or even 2 or 3) sealant(s).
Here are some web sites, including a few with comparison tables, that I found helpful and which have more in depth information if anyone has interest in digging deeper.
Handbook of Adhesives and Sealants (cvut.cz)
adhesivesguide.pdf (freemansupply.com)
Marine Caulking Products Guide - MyBoatsGear.com
Marine Sealant Adhesion Tests - Practical Sailor (practical-sailor.com)
sealant-table.gif (800×437) (boatus.com)
Screen-shot-2015-04-14-at-17.12.17.png (958×698) (timeincuk.net)
Craig
Edited by ckent323, 10 April 2024 - 12:57 AM.