13w or 15w Spiral bulbs

[mark]

What is the effective printing difference between a 13w BLB spiral bulb and a 15w spiral BLB bulb?

[holmburgers]

1 bulb alone is not going to be sufficient probably, and the wattage difference would be negligible. Using 2 CFL BL-bulbs at about 14 inches, my exposures were underexposed after 1 hour.

I recently built a 7-bulb array, and so that difference in wattage would equate to about 1 extra bulb. No word yet on printing times.

HTH!

[JBrunner]

13.4%

[holmburgers]

*searches for like button*

[Mike Wilde]

I build a UV light box with 9 -13w BLB spirals, with the base up, evenly distributed over a box that will hold a contact print rig up to 16x16". Exposure times with Ware's cyanotype vary between 10' and 60', depending on how long ago I coated, and how dense the negative is.

[holmburgers]

Mike, have you had any trouble with inconsistent output from the bulbs, that you know of? I've been told by some (ok, one) that CFL BLB's aren't stable enough for demanding processes (color carbon for instance).

[mark]

13.4%

Smart ass

[mark]

So basically the difference in printing time will be faster with the 15w bulb but not by much?

[holmburgers]

basically.

But are you planning to only use 1 bulb??

[mark]

No a bank of 6-9 on 6 inch centers