Seam Compounds - Yet Again

[SNagy]

I know this subject has been debated a number of times. I am trying to decide what underwater seam compound to use. I find Interlux 30 hard to work with. Has anyone got any experience with 3M 4200?

Thanks for the patience with this topic again.

-Steve

[bottompaint]

BoatLife polysulfide. Becuase it is soft when cured and allows the seams to close as the planking swells.

[TimothyB]

3M 4200, 5200 or 101.. they are all adhesives and not Seam Compounds.

People USE them as seam compounds, but they don't perform all of the duties of a standard seam compound, including not being easy to get out in order to inspect or replace caulking. Also if you have ever used regular oil based seam compound, the 3M stuff has a tendency not to stick unless you cut out the oily wood.

BoatLife polysulfide is the modern seam compound. Good stuff.

Linseed oil putty with white lead is the traditional seam compound, and is pretty durn cheap too.

Asphalt "tar patch" mixed with portland cement is a classic workboat seam compound for below the waterline. Remarkably cheap. Remarkably capable. Remarkably hard to make look good, fair or paint over.

Check out the FAQ and/or grab ye a book like Wooden Boat Renovation.

--T

[JFH]

I use Boatlife and 3M 101. The 101 tends to stick a little better and is a little harder to remove. The boatlife is good stuff and is easy to apply but, the stickiness is related to prep. of wood beforehand.

Do not use the 5200 or even the 4200 if you intend to ever take the stuff apart to fix something.

Good luck,

Jim

[Noah]

I used the Interlux stuff this year. It isn't real easy to work, but once you get the hang it goes pretty quickly. First, I found taping the edges of the seam helped get a clean seam. The warmer the stuff is the easier it is to work into the seams. You will have a fair amount of wastage, but that's ok.

I found that going back over the seam a few hours later (warm weather) as it begins to harden was the best time to scrape off the excess with a putty knife leaving a clean seam. If I needed to clean it up further I would go over it with a sander the next day.

I know others who have personally tried to use 5200 and 4200… Both with disastrous results. They now use Boatlife and have had very good results.

Noah