Shine a little light – A brief note on UV output degradation in LED floodlights

I’ve been using cheap & cheerful UV floodlights to expose my alternative process prints for a little over a year now. Since then, a few people have remarked that there’s a problem with these LED flood lights: their power output reduces as the unit operates due to the LEDs heating up. How bad is the problem, really, and what to do about it?

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Collimated vs. diffuse light – a cyanotype example

On a forum, someone asked how to get their cyanotypes made with 3D objects instead of a negative crisper. The fundamental issue at work here is how collimated or diffuse the light source is. Here’s a quick example of the difference between both.

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Kind of blue – A test with UV LEDs for DAS carbon transfer

So the 400nm LEDs I had been using since October or so worked really nice for dichromate carbon transfer, but I ran into trouble with DAS carbon with them. Some further testing with my bank of trusted Philips BL tubes and a little theoretical exercise suggested that at least some 365nm exposure is needed to get DAS carbon to harden reliably especially in the highlights. So I’ve been testing a bit with 365nm LED options – two in particular that seemed attractive. This is a small report on these tests.

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DAS right! – Solving the teething problems of DAS carbon transfer

Previously I wrote about trouble I was running into with DAS-incorporated carbon tissue. I just couldn’t get those tissues to transfer properly. Well, looks like I figured out why. In the process, I received some useful advice to boot, and perhaps there are some myths being established as well. Are you starting out with DAS and running into issues? Maybe some of the info in this blog can be of help.

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Beam me down, Scotty: a new ultra-simple UV light source

It’s been a while since I wrote a somewhat acrid blog about the 300W UV floodlight unit I bought from AliExpress. The tone was acrid, because 300W in reality turns out to be about 75W. The conclusion was somewhat counter-intuitive, as I also mentioned that I found the unit so abysmal, I planned to buy some more of them. The reason is simple: while the unit doesn’t live up to its specifications, it still gives a lot of bang for your buck, and most importantly, it’s super easy to implement. Well, you be the judge of that!

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A litany of woes – digital inkjet negatives and a note on dot gain mottling

I’ve sworn many times to myself that I’d steer clear of digital negatives if at all possible. Really. It’s not out of a lack of familiarity with them. Quite the opposite. I must have printed hundreds upon hundreds of them. They gave me maybe a handful decent prints, virtually all of them cyanotypes. But sometimes, there is virtually no choice but to go there…

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What a 300W UV floodlight is not

Yesterday, I did a quick test with my newly acquired Chinese ‘300W’ UV floodlight. It was immediately apparent that there is one thing very big about this floodlight: the exaggeration of its rated power. The whole thing made me curious, so I did two things: (1) opened up the unit and had a look at it, and (2) order 3 more of them. Yes, that’s right! Read on about what I found inside this unit and why I took up the ungodly plan to quadruple this mess.

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UV tube vs led: a quick comparison

I already announced in my previous journal entry, but it arrived even quicker than I anticipated: the 300W UV led source I ordered from China. Although it was also laundry-and-house-cleaning day, I couldn’t resist giving it a go. And in particular, seeing how it would pitch against the bank of UV tubes I’ve had around for years. Here are my expectations when I ordered it: (1) higher total luminous flux, so shorter exposures, (2) better collimation, so less bleed and better detail rendering. How does it pan out, you think?

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Corn print

Yesterday I made a print that I’m very pleased with. The negative just about perfectly suited my current carbon transfer skillset and as a result, the very first print of the negative is about as good as it’s going to get. Alright, there’s a few minor issues that need ironing out, but the image is quite presentable, I think. Here it is:

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