Will a LED UV light source damage film negatives (or acrylique picture frame)?

As the title says. I am going to have a go at cyanotype prints, on a very small scale, just for the fun and to see where it leads. UV sunlight being a bit scarce at the moment I am thinking of experimenting with a UV source designed for gluing (or something similar) false fingernails. The source is there, free and doing nothing except occupy shelf space so why not! It will take 6x9 negs (just). I don't know how well it will expose a cyanotype print, it works or it doesn't, that's not a world-ending problem. The question is can I use a UV light source with 120 film negatives or is the film likely to be damaged by the UV rays? If I use a clip type acrylic picture frame as a press is the acylic likely to get damaged as well (in the short term, say a dozen prints - I know that long term damage to the acylic is very likely). The source is marked lamp LED 6W, it runs off a 5v power source and just takes 6x9cm (9x12 would have been nice but if I follow up on the process it will undoubtedly mean building a slightly bigger UV source and probably getting a clubmate with a suitable printer to print me some decent negatives. My ambitions don't run to bigger than 5x4 or perhaps half-plate).

This is perhaps a bit of an idiot question but I would rather not make an obvious error (or at least a known error) right at the start.

Cheers Jo

No, certainly not for exposures of minutes up to an hour or so.

mzjo said:

If I use a clip type acrylic picture frame as a press is the acylic likely to get damaged as well (in the short term, say a dozen prints - I know that long term damage to the acylic is very likely).

Cheers Jo

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Why not use glass frame instead? You will get a better contact and higher UV throughput.

:Niranjan.

nmp said:

Why not use glass frame instead? You will get a better contact and higher UV throughput.

:Niranjan.

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Undoped acrylic actually has a better UV transmission than glass. Though most acrylic is doped to reduce UV damage which does away with that advantage.
For printing the extra weight of glass can be an advantage, helping keep the negative flat, so it's not worth sourcing the undoped plastic..

UV sources for curing nails will be long wavelength UV, probably 395nm only just in the UV. If these degrade negatives etc at all it won't be faster than sunlight for a similar exposure.

I've used UV LED strips for cyanotypes which makes printing in UK weather far more practical

Petrochemist said:

UV sources for curing nails will be long wavelength UV, probably 395nm only just in the UV.

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Not so sure about this anymore; 365nm has become quite popular for resin curing applications. I'd not be surprised if the nail curing systems have moved to 365nm as well lately.

Btw I would not recommend the nail curing systems as such since they're generally designed to cover a relatively small area. Contact printing for photography generally involves somewhat or much bigger surfaces and more power.

I presently mostly use a single 365nm 100W COB LED with a 60-degree lens for 4x5" contact prints.

Thank you for that advice which helps clarify things.

Why ask about acylic? It's a very simple little thing but if one wants to use a very small picture frame as a contact press then there are very small acrylic clip type frames available for very little money in sizes which don't appear to exist with a glass frame - like smaller than 10x15 - which is useful to get inside a nail curing device. They also have the advantage of being held together by magnets, not clips. After having used a 10x15 clip frame (glass type) last night - for some conventional 6x9 contact prints, not cyanotype - I can see that the clips aren't going to last very long being refastened after every test print as well as for the finished piece. Magnets are already becoming a very attractive idea. Of course if I wasn't deliberately limiting myself on size I do have a biggish sheet of plate glass for doing contact prints but it wouldn't do what I want in miniature.

I can see the big problem with a nail curer. As well as limited power it also has the leds arranged to focus on four individual fingertips rather than giving an even spread. I accept that it won't give good results but what the hell! It's nice to start off with some decent mistakes to point the toe of the learning curve. From there it's ever onwards and upwards! I will almost undoubtedly want to build my own UV source in the future for printing up to 5x4.

Honestly I think the nail polish hardener devices are not a great choice. It's relatively easy to build/buy something that will cover a larger area and doesn't come with the limitations of a confined space where something needs to be made to fit inside.

The simplest setup you could build is basically just a bunch of LED strips stuck to a flat board (plywood etc.) with a ready to go power supply, where everything simply plugs together. The parts for this are easy to obtain esp. if you're willing to shop from China, but also domestic shops will retail this kind of stuff (just higher price and smaller selection). Put the plate with the LED strips on 4 legs so it stands on top of a worktop/table, plug the power supply into an extension cord with a switch and you've got a switchable UV printer. For cyanotype etc. a wavelength of e.g. 395nm is perfectly fine, which means you can use cheap and easily available LED strips.

koraks said:

Honestly I think the nail polish hardener devices are not a great choice. It's relatively easy to build/buy something that will cover a larger area and doesn't come with the limitations of a confined space where something needs to be made to fit inside.

The simplest setup you could build is basically just a bunch of LED strips stuck to a flat board (plywood etc.) with a ready to go power supply, where everything simply plugs together. The parts for this are easy to obtain esp. if you're willing to shop from China, but also domestic shops will retail this kind of stuff (just higher price and smaller selection). Put the plate with the LED strips on 4 legs so it stands on top of a worktop/table, plug the power supply into an extension cord with a switch and you've got a switchable UV printer. For cyanotype etc. a wavelength of e.g. 395nm is perfectly fine, which means you can use cheap and easily available LED strips.

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This is undoubtedly the direction I will be going in (I have just cleaned the rotting foam off a Patterson contact printer to start making it useful as well), although I was thinking in terms of led UV panels. But my interest is still in printing small rather than big.
However, now that I now I won't be risking the odd 6X9 negative, I will certainly have a go with what I've got, if only for the pleasure of learning. It's only by making mistakes that one advances!

koraks said:

The simplest setup you could build is basically just a bunch of LED strips stuck to a flat board (plywood etc.) with a ready to go power supply, where everything simply plugs together. The parts for this are easy to obtain esp. if you're willing to shop from China, but also domestic shops will retail this kind of stuff (just higher price and smaller selection). Put the plate with the LED strips on 4 legs so it stands on top of a worktop/table, plug the power supply into an extension cord with a switch and you've got a switchable UV printer. For cyanotype etc. a wavelength of e.g. 395nm is perfectly fine, which means you can use cheap and easily available LED strips.

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That's pretty much the approach I went with, filling the lid of a 600x400x150mm Euro box with strips of UV LEDs. It works well for contact printing.

I'd also like to find a UV point source of reasonable power for enlarging & some other projects. I was considering a Deuterium lamp, using one of the near end of life lamps we had replaced at work, but decided they put out to much at dangerous wavelengths (right down to vacuum UV) & have awkward power requirements so decided against that route. I'd rather stick to UVA