exposure time

Dear List,
I had to double the distance of my UV-source to the neg and applied
the rule I used working with my enlarger with silver-gelatine
printing: 2times the distance , 4 times the exposure time , that
idea.
  I did the same with my gum-printing but had problems with clearing.
Is there a different treatment for UV and 'normal' light exposure? Or
is it the normal 'alt-process-unpredictable-do-it-yourself-procedure'
rule?
Cheers,
Henk

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H e n k  T h i j s  -  P h o t o g r a p h y
photography     http://www.thijs-foto.com
member of F68   http://www.f68.nl
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