Exposure Times
Exposure times for the 11X14, 14X16, and 20X24 are approximately 3 minutes for a medium density negative.  The 18X20 uses larger diameter tubes, which are less energy efficient, and takes about 4 minutes and 20 seconds for a medium density negative.  The one (1) inch diameter tubes put out more UV light than the 1½ diameter tubes.  Also, the one inch tubes can be spaced closer together, which will give more UV light per square foot of area.

High Output (HO) Exposure times versus Standard Black Light

Typically, the HO units are twice as fast the the Standard Black lights.  That is to say, the exposure times of the HO units are usually half of the times of the Standard Black lights.
 

Mike K. writes when he compares his 20 watt Black light UV Light Source to his new HO 60 Watt unit:

"I pulled out one of my most popular images.  It is a 10x12 enlarged negative with a density range of 1.92.
On the old 20 Watt UV unit w/ 100% palladium I had to print this negative at 360 seconds (6 minutes).
My comparison shows that the new exposure unit with 60w bulbs prints the same negative in 105 seconds vs 360 seconds with the old unit.

One pyro/pmk negative that previously took 10-1/2 minutes printed in 215 seconds (3min 35 seconds).

"I no longer have time to coat between sheets or read a book. ;-) "
Mike K.-
 
 
 
 
 
 
 
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