Do seams have to be perfectly clean

[modwena]

Do seams have to be perfectly clean to use polysulfide?
My boat is redwood on oak

[Scott Rosen]

Only if you want the polysulfide to stick.

The application instructions for any polysulfide will tell you how to prepare the seams. Typically, you need to clean and degrease the seams. Apply the appropriate primer. Then apply the polysulfide.

[Art Read]

You know, I've read those small print instructions and tried to follow 'em as best I could where ever I've used this stuff. But it seems to me that the LAST problem I've ever had to worry about was getting the stuff to stick! Hell, just getting it onto the intended surface before it inexorably "stuck" to something else, (the putty knife, the surrounding wood, me, the cat, etc., etc...) was the worst part...

[RGM]

Check out DETCO seam compounds at www.sterlingcoatings.com (http://www.sterlingcoatings.com) . There's some good information on their website regarding their products. It's a good way to go if you're leaning towards a "rubber" type of seam compound. Call them up and see if they have a distributor in the U.K. and a manufacturer's rep. that can talk to and possibly visit your boat. As with any "rubber" seam compound, read the fine print, twice, follow the directions and check to see that the shelf life hasn't expired before you purchase the material. As Scott indicated, clean and degrease the seams, use the recommended primer. Good luck.

[Concordia41]

Well, this year's award for the short concise answer goes to ..... drum roll... Scott Rosen

Seriously though, I feel modwena's pain. I was about to ask this question when our deck project got derailed. Having meticiously reefed at least a hundred linear miles of deck seams, and gone back over most of them for good measure, there are still minute amounts of polysulfide in the grain in the interior edges of the seams.

I took some pictures to post, but when we got the shed top up the deck work slid down the priority list and I never got around to asking the question.

- M

[Scott Rosen]

M,

Did you go over every seam with 80 or 100 grit sandpaper? That's the final step prior to cleaning with a solvent or detergent like TSP. You can stick the paper on a stiff putty knife to get it into the seam and sand the sides of the seam squarely. It's a rotten job, but all of those little details will make the new job last longer.

[rodcross]

Redwood...Redwood... I read this thread and the last and this Redwood is bugging me. Am I right that Redwood doesn't like to be glued?...Doesn't like to take paint?...Moves a lot?...Expands and contracts a lot?...Doesn't like to be bent? Is this hull soft enough for you to make a big divot with just your fingernail?
I'd hate to be wrong, but my instincts warn me that these open seams may not be as bad as they appear.

[dasboat]

You really should finish the seam prep with a sanding.I use 80 grit grinder discs.I cut them in half and go for it.These discs are very stiff,so they can be run along the inside of a seam with enough pressure to do the job w/o bending.

[Allen Foote]

WOW Scott....If I remember right you have seam compound in your seams and don't use polysulfides....but here ya are telling us to sand our seams. Hummmmm....makes me thinks that ya do'nt know what yar sayin. Modwena.....are you reefing out to recaulk or cotton caulking and then polysulfide? Are these bottom seams? What type of contaminates are in the seams? Old Interlux seam compound thats hardened and falling out in chunks?