Re: ATM When is a pitch lap too thin?

["Bill T." <twentiethwave@hotmail.com>]

Deciding when your pitchlap is too thin is a game of strategy.  A thin but 
functioning lap is okay to use, but if it finally fritzes out really close 
to the mirror being done, you'll be forced to make a new lap late in the 
game which may introduce ripple and other undesirable surface features until 
it's broken in.

There are ways to hasten break-in, such as extended pressing and surface 
sanding with with plastic netting, but in fact intoducing a new lap when you 
are almost done risks moving the light a considerable ways further down the 
tunnel. If you don't think a lap is going to make it all the way to 
completion, it's best to resurface it sooner rather than later.

Your 1/8" thick lap is pretty darned thin, but if all the facets are still 
consistent and in contact, and the channels are all equally open, and there 
are no sharp tiles lurking undernearth, there is probably no reason to stop 
using it -- except strategy.

Bill T.


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