[R-390] How are your knobs ?

[Robert Moses]

This is from my training as a chemist. I cannot cite references off
hand. I can assure you that the stuff DOES polymerize and is prone to
leave a residue film. The standard fix by chemists is to rinse with
distilled water while still wet with acetone. This gives a clean
surface. Chemists use acetone to wash glassware too, but residues can
contaminate the next experiment and produce unexpected and difficult to
reproduce results. In the chemistry business it is common knowledge that
aldehydes and keystones are capable of forming co-polymers of the
addition type.

On 05/16/2014 11:48 PM, Charles Steinmetz wrote:
> Robert wrote:
>
>> A word on acetone: it polymerizes and leaves an organic residue.
>
> Do you have references in the scientific literature that discuss this
> polymer residue phenomenon?  My quick search didn't turn anything up. 
> Acetone is rated as 100% volatile and is certified for residue-free
> cleaning to a number of aerospace and military standards.
>
> I have never observed a residue on optics cleaned with acetone,
> although there have been reports that it can dissolve rosin (used
> through the mid-20th century as an inter-element cement) and deposit
> it on the outer surfaces of a cemented-element lens.  Also, some
> commercially available acetone has trace impurities that can remain
> after evaporation, which has been reported by amateur astronomers in
> connection with cleaning telescope mirrors.
>
> Best regards,
>
> Charles
>
>
>
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