Re: [ATM] Mirror stuck on pitch lap

["Jerry" <wa4guu@verizon.net>]

I use an onion bag, one of the thicker ones that have about 5mm web of
threads about 1mm. After it has pressed and is stuck as James describes, I
use one of those kitchen sink sprayers to spray hot water on the surface as
I pull the onion sack off. I grab a corner of the web and pull it at a 90
degree angle to the lap and spray the water at the angle. The pitch softens
and as the web comes loose it pulls many small peaks onto the surface of the
lap. Apply rouge and start working. The lap drag is enormous and polishing
is fast.

I have done this for polishing, not figuring. Someday I might see if I can
control the surface shape with this kind of lap. It makes a smooth surface. 


Jerry

-----Original Message-----
From: Ken Hunter
 
James,
   
  I've never experienced what you've related but... I typically use a harder
than normal pitch.   I've left mirror and lap separated by wet Toole and
taped around the edge to prevent evaporation for many months without having
the lap destroyed when I went back to working the mirror.
   
  What is the problem with removing a few squares of pitch? The surface area
removed is surely much less than the normal channeling of the lap. I'd not
think this a problem unless you are obsessive with the "LOOK" of the lap.
   
  Ken Hunter

James Sturtevant <jhsturte@hotmail.com> wrote:
  

Been there. Tried that. I found that the netting material could be dangerous

to the health of my lap. If left pressed between the mirror and lap too long

( and, in the case of one warm summer evening, a few hours was too long) the

pitch would flow around the threads of the netting, making it impossible to 
remove the net without removing many small. square chunks of pitch. Not 
good. Parchment won't do that and, as I said, wrinkles really aren't a 
problem if you use a little care and common sense.


 
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