[ATM] Re: Second Thoughts on Mirror Support

[dgood at aha.org (Good, Donald)]

It does not appear that the Modulus of Elasticity is given in the MatWeb
data for specific silicone adhesives nor in manufacturer web sites.  And
while the tensile strength is not the value used to calculate the forces and
flexibility, it should not be ignored since it is the point at which it
breaks.  So it looks like some testing is needed.

It should not be too difficult to build a test stand that can load a sample
at a constant rate and measure the deformation.  Most important would be the
Modulus of Elasticity for tension (Young's modulus) and shear (modulus of
rigidity) and the ultimate tensile and shear strengths (test to failure).
Testing should be for various thicknesses of adhesive, at various
temperatures, for various surface conditions (polished and rough), and for
various adhesives and base materials.

I propose the following materials:
Base materials:
Glass
	Plate
	Pyrex (borosilicate)
	BVC
Metal
	Aluminum
	Steel
Wood
	common construction plywood
	Baltic Birch
	MDF

Adhesives:
GE Silicone II
Dow Corning 732
Aquarium silicone
Gasket silicone
Contact cement
Epoxy
Rubber cement (for comparison)

Temperature 0-60F (~ -20 - +20C)

I have started collecting some adhesives, but I could use some help with the
glass.  I would be looking for otherwise useless (broken?) pieces of thich
plate, Pyrex, and BVC glass, scrap plywood, aluminum, and steel - all in
small pieces (1 to 2 inches) that I could make 1 sq in. samples from.

Suggestions for other materials used in mirrir mounting are welcome.

If anyone would like to contribute broken or scrap material, please reply
off-list for address.
Thanks,
Don Good



-----Original Message-----
From: Mark Holm [mailto:mdholm@telerama.com]
Sent: Thursday, February 05, 2004 7:56 PM
To: Jeff Anderson-Lee
Cc: atm@atmlist.net
Subject: Re: [ATM] Re: Second Thoughts on Mirror Support




Jeff Anderson-Lee wrote:

>
>
> Wrong material.  Try one of the following:
>
> http://www.matweb.com/search/SpecificMaterial.asp?bassnum=PDOWC03
> Dow Corning 733 Glass & Metal Sealant  (335 psi)
> http://www.matweb.com/search/SpecificMaterial.asp?bassnum=PDOWC12
> Dow Corning 832 Multi-Surface Adhesive/Sealant  (350 psi)
>
>
Those are still tensile strength numbers listed at matweb, not modulus 
values.  Got to have modulus here.  Strength isn't the right number at all.

Mark Holm


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