Re: ATM 14.5 inch mirror stuck to pitch lap

[The Silent Observer <silent1@ix.netcom.com>]

David Shelton wrote:
> 
> Hello all,
> 
> Last night I stretched Saran plastic wrap over my pitch lap and placed
> the mirror on top.  In no time it was stuck fast.  I can't budge it.  I
> had done this before, even leaving the mirror atop the lap overnight
> with no problems.  The difference this time is that both lap and mirror
> were dry.  Any ideas how to seperate the two without destroying the lap
> would be deeply appreciated.

Put the whole assembly in a bucket of cold water with enough dish soap
in it to foam when you agitate it.  The water should be deep enough to
cover the mirror (TOT), and wet the pitch, but need not be high enough
to dampen the pitch base (so you won't risk ruining a plaster tool).

Leave it to soak for at least two hours, preferably overnight.

Come back in the morning and you should be able to push the mirror off
the Saran, likely without scratching (assuming the Saran was clean when
you put it down).  Be very careful with this operation; I did mine (the
one time it stuck, due to leaving it sit for a month after pouring the
pitch because of a basement flood) in a dry bucket to prevent the tool
or mirror from flying across the room if they released suddenly instead
of gradually.

Once separated, coat the pitch with a layer of thickish cerium
oxide/water mix, and cold press for at least an hour (to get rid of the
wrinkles transferred from the Saran) before you try to polish.  And next
time you put them together for storage, put a soapy cerium mix in
between instead of saran, then wrap the edge in tape to prevent
evaporation that will glue them together again.  Or if you'll be
polishing again in under a couple days, leave them separate with the
working side up and protected with clean, soft paper towels.

-- 
Some of their knowledge is corrupt, and inaccurate, being gleaned from
all manner of sources.  But like us, they are wizards too.
                                                    -- Jaldis the Blind

Donald Qualls, aka The Silent Observer           NAR # 70141-SR Insured
Rocket Pages                http://silent1.home.netcom.com/launches.htm
Telescope Pages            http://silent1.home.netcom.com/astronomy.htm

Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.