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Re: Storing leftover silicone sealant

I share your frustration, Dennis, but have (sort of) controlled it at 
times. Explanation below.

Dennis W Heltzel wrote:

> Does anyone have any hints for how to keep a tube of silicone sealant
> usable ? No matter how tightly I cover the tip, it "cures" progressively
> down the tube and it is very hard to remove the plug of cured sealant to
> use the remainder of the tube. Right now, I figure on only getting 1-2
> days of use from a entire tube.
> I figure someone who understands exactly how this stuff cures has figured
> out a magic formula for stopping the curing process and extending the
> life.

Most consumer silicone RTVs are caused to polymerize by using water as a 
catalyst. They get the water from the water vapor in the air, which very 
slowly diffuses into any exposed surface of the wet goo.

The trick seems to be to minimize the exposure to the air, particularly 
at the tube tip. Keep the cap on when not actively extruding silicone. 
Always squeeze out a tiny extra bit of the exposed surface and apply the 
cap with a wiping action to scrape off that last tiny exposed surface, 
so the stuff still in the nozzle is pretty free of air-exposed stuff.

If enough H2O is already inside the tube tip, the polymerization starts 
there, and keeps going right down into the body of the material, even 
without more air (water vapor) being added. It is sort of like a chain 
reaction. The forest keeps burning even after you blow out the match.

Waste that last 1/2" in the nozzle as you cap it.

Sometimes this actually seems to work!


PS. Apologies if this is a duplicate. I posted it a couple of hours ago, 
but I think my Norton may have fouled up the "send."

Wright Huntley -- 209 521-0557 -- 731 Loletta Ave, Modesto CA 95351

"All Congresses and Parliaments have a kindly feeling for idiots,
and a compassion for them, on account of personal experience and heredity."
                                 -- Mark Twain --

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