- Joined
- Sep 23, 2006
- Messages
- 193
- Format
- Large Format
Cyanotype and Van Dyke Brown. I want to do gum when things are slow this winter.
I'm a little reluctant to give printing times as how I'm mixing the formulas or my processing of the paper may not match everyone else's. I don't know how anyone else is exposing, the range of tones they look for or the density of their negatives. But for what it's worth, I used a Stouffer 21-step wedge and tested how long it took to get a maximum, uh, blue. And brown. I got about a eight stop range for cyanotype and a seven stop range for VDB. Two hours under the UV LEDs to do this for a cyanotype and one hour for VDB. When I print with actual camera negatives instead of the step wedge it varies a bit on both sides of those times.
Just for comparison exposing with the sun I've had printing times from fifteen minutes to one hour. It varies a lot for the time of day, weather and the season. With a single 25 watt spiral fluorescent BLB bulb I have from Bostick and Sullivan, a 8x10 cyanotype took from four to eight hours to expose. Again, I don't know what everyone else out there is using, but this is what I got.
The UV LEDs aren't as impressive compared to the speed of printing out in sunlight, but they are faster than my single BLB. The lack of heat from the LEDs is also a real plus -- even after being on for hours, they're only warm to the touch. I worry about cooking my contact printing frame and the delicate negatives out in the summer sun.
I'm a little reluctant to give printing times as how I'm mixing the formulas or my processing of the paper may not match everyone else's. I don't know how anyone else is exposing, the range of tones they look for or the density of their negatives. But for what it's worth, I used a Stouffer 21-step wedge and tested how long it took to get a maximum, uh, blue. And brown. I got about a eight stop range for cyanotype and a seven stop range for VDB. Two hours under the UV LEDs to do this for a cyanotype and one hour for VDB. When I print with actual camera negatives instead of the step wedge it varies a bit on both sides of those times.
Just for comparison exposing with the sun I've had printing times from fifteen minutes to one hour. It varies a lot for the time of day, weather and the season. With a single 25 watt spiral fluorescent BLB bulb I have from Bostick and Sullivan, a 8x10 cyanotype took from four to eight hours to expose. Again, I don't know what everyone else out there is using, but this is what I got.
The UV LEDs aren't as impressive compared to the speed of printing out in sunlight, but they are faster than my single BLB. The lack of heat from the LEDs is also a real plus -- even after being on for hours, they're only warm to the touch. I worry about cooking my contact printing frame and the delicate negatives out in the summer sun.
