[Alt-photo] uv content of led lights

`Richard Knoppow dickburk at ix.netcom.com
Sat Sep 23 20:18:03 UTC 2017

    I have not done a search but I am pretty sure there are spectrograms 
for the various LED lamps and maybe a spectrogram for the sensitivity of 
alt coatings like Van Dyke, Cyanotype, Platinum. I think these are 
mostly sensitive to U.V. but they may have some longer wavelength 
sensitivity too. The problem with an LED or even a tungsten lamp with a 
filter is that the eye tells you only the predominant output color. For 
instance, red party lights are mostly not safe for conventional blue 
sensitive printing paper. An LED or array of them with a filter would be 
safe because the filter would eliminate wavelengths that might fog the 
sensitive material.
    Of course, the proof of the pudding is in the eating so Marek's 
comment below answers the question in a practical sense but it would be 
interesting to have the data too.

On 9/23/2017 1:00 PM, Marek Matusz via Alt-photo-process-list wrote:
> Matti
> I coat under 3 leds about a meter from paper. I like bright light to see coating. No issues with cyanotypes.
> Marek

Richard Knoppow
dickburk at ix.netcom.com

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