Silicone caulking as a metal adhesive

While experimenting with making rubber moulds from silicone caulking I bought in Home Depot (not even the good stuff!) I found that the compound adhered to mild steel with indecent tenacity. I had to throw two objects away because the "mould" adhered to them in spite of my best efforts to remove it.

I filed this experience for future reference. If one needed a strong joint of two metal components with some "give", this seems worth considering.

Has anyone used silicone caulking or similar such to join metals?

Reply to
Michael Koblic
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Silicone comes in a whole bunch of "flavors". The stuff you buy for caulking should be pretty good for adhesion to most materials except plastics.

Some info that might be of help...

Add glycerine to the silicone you buy at the hardware store and you get something that can cure without exposure to moisture. Four drops per ounce, I think, is the right mix.

Use some sort of parting agent with this and especially any of the PU products.

RTV silicones made especially for mold making (two part) are readily available. Usually cost in the order of $25.00 a pound.

The Yahoo group "casting" deals with this sort of thing.

My web site has pointers to a couple of books about mold making. Look under resources.

DOC

Have robots. Will travel. http://www.robot-> While experimenting with making rubber moulds from silicone caulking I

Reply to
doc

BMW is using a Dow Automotive adhesive to replace a lot of welding in the 7 series.

Reply to
Pete Keillor

the dow adhesive that I'm familiar with is a urethane, not a lsilicone - it is hugely stronger than the silcone calking

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Reply to
William Noble

Silicon sealants exude acetic acid, causing rust and that's why a butyl compound is used for auto glass installations.

Reply to
Stupendous Man

yes, and the urethane is MUCH MUCH stronger - if there is interest, I can explain, suffice it to say for now that I've used both on a large piece of glass and if done right the Urethane is amazing

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Reply to
William Noble

Yes, it works, but 3M 5200 works MUCH better as an adhesive and it hardens up 20 points harder than RTV on the Shore "A" scale and it's paintable. Steve

Reply to
Steve Lusardi

There are a large number of silicone adhesive formulations that do not exude acetic acid. They are known as neutral cure or oxime cure. Check the Dow-Corning site for examples.

Randal

Reply to
Randal O'Brian

Is this a relative of such adhesives as Sumo or Gorilla glue? I have been disappointed with both. They are no match for epoxy (West system, JB Weld). They work fine for wood, provided you can sand afterwards as they swell up and exude from the joint for quite a while.

But I would certainly be interested in details.

Reply to
Michael Koblic

Two-part polyurethanes, which is what I think these guys are talking about, are not much like moisture-cure polyurethanes, which is what Gorilla Glue is.

Gorilla Glue has its uses, but the two-part stuff is more like a tenacious, more-flexible epoxy. Its adhesion is tremendous, even on metals. It's an industrial product. There may be consumer product versions of it, but I've never seen any.

-- Ed Huntress

Reply to
Ed Huntress

I've used neutral cure silicone adhesives for decades on satellite hardware. Some is air cure, some is 2 part.

Doug White

Reply to
Doug White

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