Hi all
A while ago I built an exposure unit, just a wooden box with two double-24" blacklight strips and an acrylic top. I didn't know it until well after I had built it, but I got regular blacklights, when I should have gotten the kind that look white, not black (Someone correct me please if I'm wrong). It burns slowly because of it, around 27 minutes. I want to get the burn time down to under 5 or 8 minutes, without changing anything other than the bulbs. So, anyone who has built their own successfully, what would you guys recommend for bulbs? and also, where I should be able to find them for a decent price?
Mine is not home made, but it does have 4, 24 inch unfiltered blacklight tubes. I expose my screens (I use a pure photopolymer, not a 2-part emulsion) in about 22 seconds. With the proper bulbs, you'll do much better, but you need to get rid of the acrylic and get ¼" CLEAR safety glass with NO UV protectant/film in it. The acrylic will scratch and even if you can't see the scratches, they'll be enough to give you less-than-sharp screens.
I know acrylic's not the best thing. it's already showing some very minor scratches. I will replace it soon. Where's the best place to get glass like that, just call around glass shops?
And the unfiltered blacklight tubes, are those the ones that look like white tubes ? Does home depot or other hard ware stores have them, or is it more of a specialty item that I'll have to seek out?
As for the glass, you SHOULD be able to get that at any glass shop. Of course, the smaller the shop, the less likely they'll have it in stock. As for the bulbs, you should also be able to get them at places like Home Depot or Lowes or maybe even your neighborhood Ace/True Value hardware store. I erred when I said mine were 2 foot bulbs. They're actually about 17". Made by GE and the bulbs are "F15T8BL".
Do you think that's the right kind? It doesn't say unfiltered, but it's blacklight that looks like a regular tube, so I think it's the right ones to get. If it is, I'll order some immediately!
Do they cut it to size? Is that something I could do myself if they don't?
No but they sell a cutting kit right next to it, its real simple, you cut it with a special rotary razor and "snap" or "pop" it and it will cut right off. If homedepot doesn't sell the kit, other craft stores will.
The F20T12BL tube you gave the link for is the right kind. F=Florescent, 20=watts, T12=diameter, BL=blacklight.
Wonderful. Thank you so much for your help. I ordered some from topbulb.com. Pretty cheap, $9 each.
ftembroidery, can you tell me more about your exposure unit? I just want to get a very rough idea of how quickly I'll be able to burn screens. How far from the bulbs is your sheet of glass upon which you put the film/screen? Also, exactly what emulsion are you using? My gallon bucket is dwindling, so I'll be buying in the next month or two, and want to get something quick burning but good for both plastisol and water-based printing.
Thanks again.
My bulbs are 1 and 5/8" from the bottom of the ¼" glass. I use Murakami TXR. While I will occasionally use a very coarse screen (110), most of my screens are 255 to 305 and I get good exposures/washouts with about 22 seconds of exposure time. Of course, all bulbs degrade over a period of time, so that will change.
I am in the process of building a single-point metal-halide unit with vacuum. I have purchased an OLEC AL-9 (1000w) Lamphead and OLITE AI-121 Integrator which will measure light units and automatically adjust exposure time as the bulb degrades. I would not be surprised to have exposure times of 8 to 10 seconds with this unit.
FTEM, in ref to building your metal halide unit, what type of bulb are you using (model # or something). Correct me if I am wrong...don't these bulbs take a while to light? If so how do you control that? Thanks
JMD, I'm using an OLEC AL-9 Lamphead. It comes with a 900-1000 watt MH light bulb, a built-in photocell for measuring light units and sending that info to the Integrator. It also comes with a built-in, motorized shutter, so when you power it up, the shutter closes and the light gets to full intensity. I wait until the built-in cooling fan is running before I even think about triggering the light either with light units or seconds. The OLITE AI-121 Integrator controls light intensity (low, medium or high) and operation perameters. Both units are made by OLEC. It is going to be used as an overhead light unit shining down on the screen so I can build additional storage area under the vacuum blanket area.
Did you order these lights and was it the correct ones? I had bought some unfiltered black lights for 20 dollars. If this is the correct ones then I will buy from here instead.
Do you think that's the right kind? It doesn't say unfiltered, but it's blacklight that looks like a regular tube, so I think it's the right ones to get. If it is, I'll order some immediately!
Best bulbs for an exposure unit? 
Re: Best bulbs for an exposure unit? 
