Re: [ATM] First Pitch Lap - any tips?

[Jarvis Krumbein <jkoptic@juno.com>]

To make a really complete lap in one shot.

	First, apply aluminum foil as previously described.  Don't forget to oil
the mirror first and get the foil as smooth as possible.

	Second, put the masking tape dam around the edge of the mirror.  I've
used both masking tape and the old fashioned glued paper tape which 
think is even better.

	Third, apply a grid for the facet channels using RTV caulking.  Use the
white stuff rather than the clear and make the lines, ridges actually,
neatly.  Don't try to mop up any boo-boos, just leave them.

	Forth, let the RTV cure for 24 hours.

	Fifth, paint the aluminum foil/RTV with a thin slurry of CEO.

	Sixth, pour the pitch and apply the tool as previously described.

	Seventh, when the pitch has cooled sufficiently, strip off the tape and
slide the lap off the mirror.

	Eighth, peel the aluminum foil off the tool.  The RTV will also come off
with the aluminum but if it doesn't, it can be easily pulled from the
pitch.

The end result is a lap already channeled and ready for a final press
before polishing.

My wife likes the method because there is absolutely no mess from the
channeling.  I've used this method for years and always had good results.
 Note that this is not a method for the impatient as you do need the 24
hour RTV cure, but then, after 60 years of mirror making, I'm in no great
hurry.

Jarvis Krumbein
<jkoptic@juno.com>

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