Sudbury Elastomeric Marine Sealant

I have used this product for years. Unfortunately all 3 Tubes shipped to me were 2-3 years old (2018-2019 mfg date) and only one of the tubes had material which could be readily expressed from the tube. The other two tubes were partially cured and unusable.

Used to seal the rubber mast boot at the deck on a sailboat for waterproofing. The mast moves around 1/2"" or so at the deck so regular sealants break free and leak. Injecting this stuff seals it for 5 years or so (it's elastomeric) because it flexes and moves around as the mast moves keeping it sealed. It's like honey that never gets drippy. After 5 years or so it hardens up and has to be dug out and replaced with new. Been using it for 30 years, and am concerned it's getting hard to find and is now considered Hazardous Material, which is reasonable considering the volatile solvents that flash off during application. One caveat is it has a limited shelf life even unopened, so buy it fresh, use it all and discard the container.

I have used it above the water line water line many times bedding all types of hard ware. Have not found any faults. Beats 3M products hands down.