Re: Newton Rings? Dust? Something else?


Peter Charles Fredrick (pete@fotem.demon.co.uk)
Mon, 05 Apr 1999 17:47:58 +0000


Dear Adam,

Some gravurists I have talked to have mentioned that dust on the screen can
cause these spots. That doesn't make sense to me.. how could a piece of dust
(microns wide) cause a 5mm spot? But, lots of stuff about photogravure makes
no sense at this stage.

It is important to note that these spots DO NOT occur when I am exposing a
positive film to the tissue. I've made a number of carbon transfers with
this tissue that show NONE of these problems. It only occurs when using the
screens.

These problems can be associated with dust or poor contact or a combination
of both. A spot of dust could cause a much larger out of focus area acting
like the centre post of a tent holding the screen away from the light
sensitive surface. If it is Newton rings you should be able to see the ring
like patterns on the image.

Hope this helps

Pete

Ps Why 70% screen I would have thought that 50% should be right ?

http://www.fotem.demon.co.uk/ To visit petes parlour gallery, there is now a
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