heat filter deterioration

[P3D Richard Twichell <73163.3423@xxxxxxxxxxxxxx>]

Re:  recent discussion of TDC projector heat-absorbing glass deterioration: 
 I have seen this recently also - a friend sent me one of his TDC716 heat 
filters for my opinion - I could not believe that the glass itself had 
caused the problem - it looked like the corrosion one finds on old car 
battery terminals (or with bad luck inside one's red-button Realist!).  It 
infected both sides and was impossible to remove.  I concluded that someone 
must have put polarizing material on the glass which "burned in".  

However, with these new reports on the subject, I think I was wrong, and 
that it IS the glass itself.  I would like to hear more about this, from 
anyone who might know what's going on, and also any other reports of the 
same condition.  I have two TDC projectors (three including a little "mono" 
one) and there is no sign of this problem on any of them.

Two related thoughts:  the mono projector uses the same size heat glass as 
the 116 and 716 and was a five dollar flea-market item.  Worth the price 
for the glass alone.

Also:  (this is strictly hearsay) The new bright lamp modules Kodak is 
making for Carousel projectors were seen by many of us for the first time 
at the Rochester NSA convention.  Kodak loaned us 16 of them and they were 
very effective.  They work by eliminating the heat glass and using a cold 
reflector instead of the usual mirror which lets the IR pass through and 
reflects the visible light.

Now the hearsay part:  A source close to Kodak tells me that they are 
making a virtue of necessity;  that although the new modules are being sold 
as an accessory now, they will be standard in future Carousels.  Reason:  
Corning Glass, which makes the heat glass, informed Kodak that they would 
have to charge much more for the glass in future because the acidity of the 
process necessitated rebuilding their kiln after each batch.  Again, 
strictly hearsay.

Dick Twichell  


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