Re: [ATM] RE: RTV Silicone clear or colored

[Kevin Whitefire <chaosopher23@yahoo.com>]

Clear or colored silicone would have a marginal
adhesion difference.  The reason we choose clear is
that silicone is generally not paintable and will
adhere to a painted surface as long as we don't rely
on that surface for mechanical strength.

Unless you have a 'scope with the exact color of the
silicone, clear is the advantageous color(less)
choice.

Kevin of Eastern Iowa
Seeker of the Darkness

--- Mark Holm <mdholm@telerama.com> wrote:

> >some new fangled RTV glue at the time (called
> Silicone II 
> >perhaps) which didn't have that classic strong
> Ammonia smell when it was 
> >wet
> 
> I think the smell you are referring to is actually
> acetic acid (vinegar).  At least, every time I have
> used silicone caulk, the smell I have encountered
> was definitely acetic acid.
> 
> I have seen "silicone" caulk for sale in hardware
> stores that is actually acrylic latex with only a
> small percentage of silicone included.  I don't
> think the Silicone II brand is necessarily bad. 
> When I saw the stuff that was mostly acrylic, I
> could tell it was just by reading the fine print on
> the tube.  Also, silicone is inherently more
> expensive than acrylic.  I think, but am not
> certain, that it is difficult, perhaps impossible,
> to make a good, clear caulk or adhesive by mixing
> acrylic with silicone, so it may be helpful to only
> buy clear.  Also, even in true silicone, that
> pigment probably hurts adhesion a little, so clear
> is probably still best.
> 
> Several times, someone has mentioned on this list a
> particular specialty grade of silicone adhesive the
> is recommended for mirror gluing.  I think it is a
> Dow Corning number grade.  I forget the number but
> recall, I think, that it is a four digit number.  As
> I recall, one can mail order the stuff from one of
> the big industrial supply houses for a not terribly
> outrageous price.
> 
> As I recall, this "extra good" stuff is said not to
> smell of acetic acid either, because it uses a
> different curing chemistry, nethanol instead of
> acetic acid.
> 
> Try searching the archive on "Dow Corning".
> 
> Mark Holm
> 
> 
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> 



		
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