update: screw-in BLB light-box

Hello Sandy King (who first posted a query about the screw-in BLBs as a possible source of UV for alt processes) and anyone else interested in knowing how they worked.....

This past weekend, during an excellent workshop on PT/PD printing taught by Kerik Kouklis at the Cascades Academy of Photography, which is located in lovely "old town" Issaquah, Washington, I was able to compare printing times in my lightbox (6 screw-in 13 watt BLBs with the print frame 4" from Light source) with one of Edwards Engineering fluorescent tube boxes. Needless to say, the times were longer - a tad more than 10x - but the results were the same.

Stated specifically: A digineg created with Keith Schreiber's method (looks orange on screen but prints yellow-green) and printed on Pictorico OHP using an Epson 1280 (dye inks) with 100% PD soln. on Cranes "Platinotype" (B&S name for this paper) required 1 min 50 sec in the EE box, where as the same required 20 min in my box. All other factors were more-or-less (read "unscientifically determined to be" ) equal.

For the time being, as I perfect coating techniques, etc., I am not bothered by the excessive time - gives me an opportunity to make notes which I tend to forget to do when I am working at a faster pace - but will most likely give the 20 watt bulbs a try before building a larger tube box.

Anyone know right off the top of their head if I might expect exposure vs wattage to be linear in this situation (i.e., will the increase from 13 watts to 20 watts cut my time by about one-third)? If not, I will go back to some of the published data / manufacturer's data to search out the answer to this question. If it is less than linear, I probably wont bother with the more expensive screw-in bulbs, but just go right to a tube box sometime in the future.

Thanks!
Judy

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Judy Rowe Taylor
Mukilteo, WA