Canada Balsam was also used for many years to prepare histologic tissue
sections. It worked well but did tend to yellow over time. These days we use
a product called Permount that dries hard, serving as a glue, and is
optically clear and colorless. It would not surprise me in the least if it
was used to glue optical elements.
Charlie
On Tue, Jan 26, 2010 at 12:17 PM, Chuck Norcutt <
chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
> According to Wiki Canada balsam was phased out as an optical cement
> during the second world war. Whatever has failed must certainly be
> something different.
>
> Chuck Norcutt
>
>
> JOHN DUGGAN wrote:
> > Optical Instruments (Balham) have given me a ballpark figure of
> £60.00/$90.00 to separate and re-cement the front doublet to M.O.D.
> specifications.
> > The elements themselves are pristine, and re-assembly is very
> straightforward. So this is my back up option.
> >
> > I am STILL trying to get a definitive answer from Tokina UK (Kenro) as to
> whether the font element is still available from Japan, and if so will they
> sell me one - and at what cost. They do not seem particularly helpful.
> > I suppose there is not a lot of profit in it for Tokina UK if I do the
> repair myself.
> > At least I can see a way forward.
> >
> > One possible contributing factor towards the element separation is that
> running under the area where the camera bag had been placed central heating
> pipes run. The floor at that point gets "warm" not hot. I wonder if that
> could have softened the Balsam?
> > However, to counter that theory, the edge of the element is still sticky
> four days after dismantling it so perhaps it is just natural breakdown of
> the cement.
> >
> > Regards
> > John Duggan,
> > Wales, UK
> >
> >
> >
> >
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