Re: Wavelength for all Alt. Processes ?
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Processes that use the photo reduction of iron(III) to iron(II) are broadly sensitive to light at around 390 nm. Thus they work just fine with inexpensive BLB bulbs/LEDs. These sources also seem to work well for salted-paper.
Photopolymer gravure does not work with the BLB sources, as it requires the shorter wavelengths of the more expensive 360 nm sources. I have no information on how the 360 nm sources work with the iron based processes, but they do seem to work for salted-paper.
These days I use a simple plywood box with four strips of inexpensive, pre-wired BLB LED strips which gives me 10 or 15 min exposure times for cyanotype and salted-paper.
The nice thing about BLB LEDs is you don't need to really worry about managing the waste heat. My box has a few vent holes leftover from when it had fluorescent bulbs but no fan. It barely gets above ambient temperature by 15 min.
On Sun, Sep 5, 2021, 3:13 PM Michael <pixelwaster@...> wrote:
I used to have a nice list of what range of light worked with what process. I suspect it is on the drive that died.