built a lightbox, first two test burns did not wash out at all. . . mixed new batch of emulsion, and test step wedge last night all washed out, but at least i could start to see the design on the top part. . i think it may simply need to be exposed more, but i think the sylvania 200w heat lamp bulb I am using might be cause some problems. . .using a regular 120v light fixture, where can I find an affordable bulb that will do the job right, mostly because I don't know how to tell what is right, because the light bulb boxes don't say, "UV lighting" or anything. . ?
exposure unit bulb?
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You can get a 500 watt halogen lamp at home depot for like 8-12$. I've never tried the bulb your using, but my not-so-expert opinion says that doesn't sound right
It sounds like you are getting some exposure with it though. If you're only getting the design from the step wedge, you'd need to increase 7 steps, so that's that, quintuple the exposure time? I don't think you're getting enough UV. How long are you exposing for?
It sounds like you are getting some exposure with it though. If you're only getting the design from the step wedge, you'd need to increase 7 steps, so that's that, quintuple the exposure time? I don't think you're getting enough UV. How long are you exposing for?
The lack of UV, and my lack of understanding of UV, is why I posted this. . .but, I did the test wedge with one minute increments up to five minutes. . my teacher had made a similar light box that he said was perfect at five. . . when i tried the time recommended on the box, about 17 minutes, nothing washed out, and same with the next one i tried at four, and then a test wedge up to three min. because i was under the impression that it was being overexposed as nothing was washing out. . . I don't know what you mean by seven steps, but the wedge up to five minutes turned out like: the lower minutes completely washed out, and you could see the design at least on about four and five minutes exposure time, but that too washed out almost all the way before I put any stencil remover on it.
I read on another forum that halogen works, but is a very poor source of UV, but couldn't find a straight answer on what to get?
I read on another forum that halogen works, but is a very poor source of UV, but couldn't find a straight answer on what to get?
Oh, you have one of those step wedges. Where you move the paper across it? Now I get ya.
You have a few options on what lights to get. Metal Halide is the best. Unfiltered black lights work ok too (not the spencer gifts party black lights, these are different), Halogens also work. They have enough UV, they just aren't efficient at it, so they put off heat. I'm sure every light puts out some amount of UV, but it will take longer to burn the image. So there isn't really a "straightforward" answer. If you went to 5 different shops, you'd probably see 5 different lights with 5 different exposure times.
Just some basic trouble shooting; Are your screens entirely dry? Are your transparencies dark enough? How much pressure are you using to wash out?
You have a few options on what lights to get. Metal Halide is the best. Unfiltered black lights work ok too (not the spencer gifts party black lights, these are different), Halogens also work. They have enough UV, they just aren't efficient at it, so they put off heat. I'm sure every light puts out some amount of UV, but it will take longer to burn the image. So there isn't really a "straightforward" answer. If you went to 5 different shops, you'd probably see 5 different lights with 5 different exposure times.
Just some basic trouble shooting; Are your screens entirely dry? Are your transparencies dark enough? How much pressure are you using to wash out?
Thank you, I am going to recoat the screen after work today, and hopefully by tonight it will be dry enough to run a longer test wedge and see what happens. . ha, I gotta do it at night cause i am just washing them out with a hose of the house, and I am not sure if the sun outside had an impact on one of the screens that didn't wash out at all or show the design. . .
yes, i quickly realized that was the problem when I read a forum with a guy who exposes his screens in the sun all the time, and it only takes thirty seconds to a minute. . so that could have hardened mine to exactly why nothing washed out. . thanks though, that trash bag thing is an idea being that I am not always going to want to wait til nightime. . I will tonight though just to take that variable out of the equation! actually, I think I am going to ask my dad if I can relocate to the garage accross the street. . theres a water point, and a drain inside there. . thank you again, and hopefully I will have some better news tomorrow. . I CANT WAIT TO START PRINTING AT HOME!!!!!!!
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Depending on how many clouds in the sky..... and what lattitude you're at... direct sunlight will expose pure photopolymer emulsion in about 5-15 seconds!!
Dry screens in "complete" darkness. Not even light coming from under a door is safe. Yellow light is not a "safe" light with pure photopolymer emulsions. Red is the only true safelight.
The "heat bulb" is wayyyyyyy bad! Emulsion is a photographic chemical and is affected by heat. Use a 1,000 watt quartz halogen bulb.
Email me and I'll send you plans for a "kit" no charge!
Dry screens in "complete" darkness. Not even light coming from under a door is safe. Yellow light is not a "safe" light with pure photopolymer emulsions. Red is the only true safelight.
The "heat bulb" is wayyyyyyy bad! Emulsion is a photographic chemical and is affected by heat. Use a 1,000 watt quartz halogen bulb.
Email me and I'll send you plans for a "kit" no charge!
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I think that what the heat lamp radiates is infra red, not UV. It is designed precisely to generate heat
Get a halogen work light, and make sure to remove the glass, because it is a UV filter and you don't want any UV be filtered..
With it 12 to 14 minutes should be enough.
I know it is not the best, but it works ok for me.
Have a Metal Halide bulb and ballast sitting in my shop, but because the halogen works so good for me, it will probably be there for some more time
when you say, take off the glass, im assuming you mean, take off the bulb part of the light, and if my assumption is correct. . . how in the world would you go about doing that. .
. . . I don't remember if it is a heat lamp or just a halogen bulb. . i bought it a while ago, and don't remember what menards sold me when i showed them the manual that came with my kit, but it does get pretty hot, so I am going to run another test wedge with longer exposure times tonight. . and if the results are still as horrific as I have been experiencing, I will be at the hardware store tomorrow morning.
. . . I don't remember if it is a heat lamp or just a halogen bulb. . i bought it a while ago, and don't remember what menards sold me when i showed them the manual that came with my kit, but it does get pretty hot, so I am going to run another test wedge with longer exposure times tonight. . and if the results are still as horrific as I have been experiencing, I will be at the hardware store tomorrow morning.
He means, on the halogen work lights, there's a lens over the outer casing. It pops right off. You'll see what we mean if you end up getting one.
Well, last night, did a test wedge with times 7, 9, 11, 13, and 15 minutes. . . 15 definitely was a little too long, as a lot of it didn't wash out, and 7 was too short as most of it washed out. . feel like i am getting closer, except the results in the middle where a little confusing (I was hoping I would be able to come up with a time after this many tries that would let me make an actual screen to try printing with) . . there were some spots where the image washed out real sharp in both the nine and thirteen minute areas, but still some spots that didn't wash out in between, and some where the edges were washed away just sightly, but definitely too much to print, or would be really blurry and ugly.. . not sure if this has anything to do with the slight movements of moving the manilla envolope under the screen, or if the velum wasn't perfetly flat, but I just coated a screen, and I'm not sure whether to try running the whole thing for 12 minutes, or do another test step wedge in that time range. . I feel like those results would probably be even harder to interperet, since this trial was kind of confusing, but I am definitely not trying to cut any corners, and want to get the right time. . I am also not sure if some of the sprayout problems might have resulted from simply using the backyard hose with my finger on it to wash out. . . I think I will try using my dad's powerwasher without the power just to get a more even spray tonight. . . . Am I right by assuming that because I did get the image to show up, and wash out pretty clean in some parts, that my bulb is not the problem?
Is your screen touching the glass? You may want to put a stack of books on the screen to make sure there's good contact with the transparency/glass
If you still don't have any luck, you may want to try one of these
Exposure Calculator and Step Wedge Exposure Guide, with instructions
If you still don't have any luck, you may want to try one of these
Exposure Calculator and Step Wedge Exposure Guide, with instructions
i ran a screen for twelve minutes last night with the first design i am going to print. . . most of it washed out, and resembled the transparency, but there were some spots where the picture was still very fuzzy, and parts around the small details that didn't wash out. . . i think i will try putting something over it like that book idea thank you, because there is a space between the velum and the screen probably from coming out of the printer the way it does, and I will probably print it twice to make sure the image is opaque on the velum.
I also think I may have gotten some of the bad spots from the image I obtained being very poorly edited by my friend, because there were some pixelations around the edge that didn't show up on the compuer zoomed in to 800 percent, but they did print.
I also think I may have gotten some of the bad spots from the image I obtained being very poorly edited by my friend, because there were some pixelations around the edge that didn't show up on the compuer zoomed in to 800 percent, but they did print.
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Sounds like you may have a problem with opacity too. Doubling up on the vellum sheets will block even more UV light from hitting the screen.
Make sure you are using a vellum that is sold to "the trade" specially for screen exposing. Vellum you pick-up in an art store may 'look' transparent, but it may also be blocking UV from passing through.
Make sure you are using a vellum that is sold to "the trade" specially for screen exposing. Vellum you pick-up in an art store may 'look' transparent, but it may also be blocking UV from passing through.
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How far is the bulb from the screen, this also plays a part in exposure time.
I have a 500 watt halogen bulb in a ballast about 2 feet from my screen, and my exposure times are in the 6 minute area. You definently CANNOT let any light into the room, or it will dry the emulsion.
I have a 500 watt halogen bulb in a ballast about 2 feet from my screen, and my exposure times are in the 6 minute area. You definently CANNOT let any light into the room, or it will dry the emulsion.
What are the kind of lights you need to have in there so i can have some light while i am getting it ready. . . I know I have heard red lights are the only safe ones. . . is this just the kind of red lights they have for regular fixtures at menards?
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