@silkscreentechs _ have just joined and seen that the screen printing area is possibly looking at making a exposure unit. I may well have some UV fluorescent tubes soon as they are due to be tossed from my work. Let me know if these are of any use as I can put them aside. They are 4ft, 36watt UV blacklight tubes. There are possibly 12 tubes but not a fully matched set.
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what would you use them for?
You can use these to make an emulsion curing unit for the UV sensitive emulsion which is used for screen printing.
Cool! yeah we need to either build or buy a unit… either way we probably need a pledge drive to get some funds to get it started…
OK, I will earmark them when they are due to be disposed of just in case. I suppose the reasoning for building v.s. purchasing would mainly be on cost related to the maximum screen size the vacuum bed can handle. the reliability of a manufactured unit would, you hope, be a lot better as well.
Yea, sounds good - what is the timeframe they are looking to get rid of them?
I think this will probably be March/April time but i would have to double check this. The supplier we use for our UV tubes is a company called CP -lighting in Surbiton. Does anyone know what specifications the uv tubes normally need to be for curing screen printing photo-emulsion? IT may be the tubes that I will have access to are not the right wavelength or output rating for curing the resin anyway.
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Was looking at stuff like this…
@silkscreentechs? Look good, maybe we start the pledge drive…
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What Sam is offering is a size of UV tubes that would correlate with the size of our biggest screen. Just last year when I looked I to it with @jackL there was a full sized natgraph for ÂŁ500, we can wait this out OR build one. But up to screentechs I suppose. I am just a humble turner.
Yeah I think we need 500-700 for a good used unit. Even building one would cost a few hundred at least and take a long time. If we ever want to sell it, the Natgraph type unit will keep its value, a DIY one will be next to worthless…
I think we should buy one…
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What’s the frequency needed?
Can we use LEDs?
UV LED’s are definitely a much better option than they used to be. I think all new units these days are heading the way of LED’s due to the progressive fluorescent tube ban. I hear from a lot of manufacturers that they are slowing down production a fair bit and are only manufactured in a few European countries now. Some companies I use as suppliers at work halted production super quicky.
I had a look yesterday for photo emulsion by where the screen table is but couldn’t find any. I imagine wavelength details will be on the data sheet of the specific photo emulsions. Would hazard a guess it would be UVA but it may be a matter of it curing faster at higher energy UV.
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~ 360 - 400nm. But a lot of it and as even as possible over the screen.
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And for good reasons, Fluorecent tubes are nasty, full of mercury , they are wasteful to run, the only good thing about them is the uniformity of the beam.
“Let’s coat a glass tube with nasty material and discharge plasma into it”
Wild.
In case you don’t know we do have about 6 UV tubes and a 1000w halogen which could expose any size screen, it just needs to go further away and expose for longer