Re: ATM Re: silicone caulk adhesive strength

["Albert Highe" <ahighe@ix.netcom.com>]

First of all, that is not the limit of what the adhesive will hold. Remember
that's considered a wide safety margin. However, I'm sure its possible
someone may design a support that will fail.

For example, I use a six point floatation cell for my 12.5" mirrors. The
combined area of the six supports is approximately 2.65 square inches. These
cells have easily held 1.625" diameter mirrors weighing approximately 17
lbs. That works out to 6.4 lbs/sq. in.  I would challenge anyone to try to
rip a mirror off of the cell.  I couldn't do it. The only way I could
separate mirror and cell is to partially disassemble the cell and cut each
support pad off individually with a razor blade. The remaining silicone
caulk is so firmly attached to metal and mirror that it can only be sanded
off.

Albert


----- Original Message -----
From: "Jim Miller" <jim@jtmiller.com>
To: "Albert Highe" <ahighe@ix.netcom.com>; "grumpa" <jdubois@essex1.com>;
<atm@shore.net>
Sent: Friday, June 22, 2001 3:18 PM
Subject: Re: ATM Re: silicone caulk adhesive strength


>
> 12 tons/36sq ft = 74oz/sqin.  are there any atm primaries that would
exceed
> this?
>
> [snip]
>
>
> Finally, in a post to the ATM list, April 11, 1996, Dean Ketelsen reported
> that "100% silicone caulk you can get in any hardware store for as little
as
> $2.is currently holding the [Steward Observatory Mirror Laboratory's22]
> Magellan 6.5 meter vertically in full shear, and has been for the better
> part of a year. Granted, it only weighs 12 tons and is supported by about
36
> square feet of bond area, but there is a huge safety factor and no one
here
> is worried about it."
>
>
>