Re: ATM How do you properly cement the mirror hole plug

[Alfredo Neves <arainho_cl@yahoo.com>]

Hi,

My problem was with the epoxy ring around the core. It
rub against the lap really leaving it in a bad shape.

Alfredo

--- Richard Foulk <richard@skydive1.com> wrote:
> 
> } Alfredo,
> } 
> } I have used Plaster of Paris (NOT dental stone!)
> and wax.  You just 
> } need to hold the blank securely and then be able
> to remove it.  I 
> } would be very nervous about using epoxy--it is
> likely to put stress 
> } on the mirror and make it very hard to remove the
> blank at the end. 
> } Since you need to dig out the plaster at the end,
> I would rather not 
> } use dental stone--it is harder to chip away than
> simple plasters. 
> } With a waxed core, I just put the whole thing in
> the oven a heated it 
> } very slowly until the wax melted and the core fell
> out.  I did not 
> } put in the wax core but rather bought it that way.
>  My guess is that 
> } sealing wax (for letters) would work fine, but
> most waxes would 
> } probably be OK.
> } 
> } Good luck with your project.
> } 
> } Scott
> } 
> 
> Wax sounds interesting.
> 
> Plaster and dental stone I'm not so sure about. 
> Some plasters and cements
> expand as they cure, which would could cause stress
> on the mirror.
> 
> I think Plaster of Paris shrinks some as it cures
> (though I'm not
> certain), so it might not be a problem.  Some
> `stones' and hydraulic
> cements are designed to expand to increase strength
> and anchoring
> capabilities for some applications.
> 
> Epoxy is somewhat like your wax.  Most epoxy softens
> with heat.
> 
> And most epoxies remain in a flexible, plastic state
> after they harden
> and shouldn't be considered an expansion problem. 
> (Although some epoxies
> in large quantities can generate a fair amount of
> heat during curing.)
> 
> 
> Richard
> 


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