Polysulfide Cure Rate to Paint Over?

[preserved_killick]

I've got some woodwork I just fastened and has a little bead of polysulfide (Life Calk) that runs around the perimeter. The specs from Boat Life say tack free in 24 hours and cures in 7 days. But when can varnish go over it? I called the folks at Boat Life today and they were not very helpful. They say 1 to 3 days after it is tack free. That would be great, but I only want to do this once.

Anyone have a feeling or lots of experience with this?

-jeff

[Tom Young]

Just as soon as it's stiff enough to stand up to the brush. At least that's what I've done in the past with no problems, with varnish.

[Tim]

When it feels cured, it's fine for overcoating with varnish. How long it takes to get there will depend on ambient conditions.

Polysulfide can take quite a long time to become tack-free and cured. If you're getting impatient, mist it with water to accelerate the cure. I find that it takes 2 weeks or more to become "tack free" in the winter's dry conditions, but that it cures quickly in the more humid conditions of summer. The thinner the bead, the more quickly it will tend to reach the tack-free state.

Note that "tack free" may not be the state at which it's ready for varnish; it should be cured and rubbery. "Tack free" denotes that the surface may be non-transferable, but the product could still be softer just beneath.

Boatlife was imprecise in helping you because there's no one answer: the stuff doesn't set up in a neatly-defined time frame under ambient conditions. It takes as long as it takes, and it'll be ready when it's ready.

[Hirilondë]

It takes as long as it takes, and it'll be ready when it's ready.

And you thought Boatlife was being imprecise? ;-)

[Tim]

The hard truth isn't always pretty.

[preserved_killick]

Thanks guys. With the current NH weather forecast, looks like I'll be waiting a week anyhow.

-jeff