Author Topic: Adhesive or Sealant to make aluminium casing waterproof  (Read 1090 times)

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Offline T3sl4co1l

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Re: Adhesive or Sealant to make aluminium casing waterproof
« Reply #25 on: July 13, 2018, 11:15:40 pm »
Acetyl and amine based silicones are murder.  The resulting acetic acid corrodes most metals, including aluminum and copper (but not stainless).  Or the resulting ammonia corrodes aluminum, copper and a few others (but not steel, and maybe not tin).

Neutral cures I think are alcohol based, which is too mild to affect any metal that's not already affected by water.

Water is the curing agent, by the way.  Water breaks the alcohol or acetate or ammonia off from the silicone backbone, causing the silicone molecules to stick together.  A perfectly air tight joint will not cure, and perfectly dry air will not cure (although I'm not sure that that's enough of a problem even in very dry desert areas, as long as there is still some moisture in the air).

At least, this is true for some types, but I don't know what all kinds are out there.  The only kinds that don't need air exposure of some sort are two-component, of course.

Tim
Seven Transistor Labs, LLC
Electronic Design, from Concept to Layout.
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