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

 

[holmburgers]

ok, gotcha.

Well, 13.4% might add up by that time.. but it's immaterial as long as you pick one and stick with it.

 

[Mike Wilde]

I'm not that precise with my UV source to notice one bulb flaking a bit.

Anecdotally, they sometimes do come up to full output at different rates ( between say 2 and 10 seconds). Over a 30-60 minute exposure that is no big deal.

For me Alt process is about printing while there are other things also to do, particularly cyanotypes.

Size the paper in advance. Make enlarged negs in advance.

Coat the paper once home from work and hang to dry (I coat with a variant of the glass rod method, and find the print paper with sensitizer dries in under half an hour, if hung up.)

After dinner, paper is ready. Mount the neg and paper in the contact frame, fire it into UV box. Set the timer for 20 minutes. Do other things; make up tomorrows lunch bags, supervise homework, sort laundry, etc. Check at 20 minutes; almost always it needs at least half a stop of more exposure, so come back in another 10 minutes.

Once ready, dump in the sink, dribble fresh water into a tray to wash and clear it. Clean the dryer lint trap, check if fabric softener and laundry liquid are getting low... it is the most relaxing way to print.