Hi,Im trying to do a 4 color process job. I seperated the job on fast films and i did the halftones on Photoshop by going to image/mode/grayscale and then i changed it to bitmap. I printed the design out with my hp inkjet(scanner/copy/printer). My problem is that for some reason the halftones are not being burn on to the screen. When i go to the wash both to reveal the design, only the big letters get washed out but the halftones never expose on the screen. Im using a 230 mesh and im exposing for 6 minutes. I exposed for 7 minutes then when i went to washout the design, it was a heck of a battle to reveal the design a little bit. Then i tried laying more weight on my screen so it can stick with the design for exposing it better, but it didn't work. What would you guys recomend me doing. Thanks
looks and sounds like you are over exposing the screens. Not knowing your set up, type of exposure, emulsion, coating techniques and from the image you posted I would say it looks like you might need to drop your burn time to 4 or less min.
Have you ever done it before? It is really tough to work with half tones when you are not using a single point light source for your exposure unit with a vacuum. I am not sure I would try it with your set up, but for you to be successful you are definitely going to have to under expose to get them to come out. Also you need to use the proper mesh count and proper tension.
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Chad Pierce
Attitude Graphics Group - Screen Printing & Embroidery
230 is a good chocie and from looking at the film the lpi looks to be a large dot. Should be ok. Just need to lower the exposing time considerably. If you get a decent burn and you thing you still underexposed, you can always put the screen back on the light table for a post exposure epose This will help to harden the stencil more. Setting outside in the sunlight will help as well.
Just be prepared to go through a screen or two unbtil you get the majic number (burn time) MAKE sure you document your bruns and keep a list posted next to your unit (exposure unit) for future reference
uhhuhuh - he said unit yeah yeah expose had to do it
Thanks guys for the fast response. I tried it for 4 minutes and the halftones do reveal but i took it to the washout booth and now i cant wash it out. The halftones are slightly revealed but the image doesnt washout/water doesn't go thru it. This would be my first time trying to print process. Im using Autosol 2000 direct emulsion, im using it with the lights in my garage on. I think i need more coating expirence because iget alot lot of emulsion to the sides. Where i can i get a vacum?
You may be exposing the screen before you even put it on your exposure table. try without he light son use a UV safe light.
If your still not getting a good burn, lower the time even more.
Richard Greaves, here on the forums is the Ulano product manager and will more than likely be able to help a lot more than us. He'll probably see this post tomorrow or shoot him a PM http://www.t-shirtforums.com/members...rdgreaves.html
Hi,Im trying to do a 4 color process job. I seperated the job on fast films and i did the halftones on Photoshop by going to image/mode/grayscale and then i changed it to bitmap.
I printed the design out with my hp inkjet(scanner/copy/printer). My problem is that for some reason the halftones are not being burn on to the screen.
When i go to the wash both to reveal the design, only the big letters get washed out but the halftones never expose on the screen.
Im using a 230 mesh and im exposing for 6 minutes. I exposed for 7 minutes then when i went to washout the design, it was a heck of a battle to reveal the design a little bit. Then i tried laying more weight on my screen so it can stick with the design for exposing it better, but it didn't work. What would you guys recomend me doing. Thanks
Fluid, my biggest fan this week.
I question whether your HP positive is opaque enough to make halftones.
If the halftones don't wash out the got exposed and won't dissolve with water. It is certainly handy to have an 'antique' film photo positive to use as a standard. Every emulsion manufacturer makes a film positive to go with their exposure calculator.
Make and print a halftone grayscale and expose it on a stencil.
3%
5%
10%
15%
20%
30%
It is easy to fill square with these tints in Illustrator or CorelDRAW. Learn to expose the test patterns.
Print them and compare the halftones on the positives, to you print with a magnifying glass.
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How are you measuring? retired Ulano Technical Support Screen printing since 1979 - SGIA Academy Member
I tried another screen. I did this in the dark. Ok i coated the screen with emulsion but only on one side which is the side that touches the t shirt and i exposed it for 4 minutes. I got the halftones but not all of them. I only got the darkest halftones. Should i increase my exposing time or should i decrease so i can get the other halftones? Here are some pics-Thanks
You need to make a gray scale using the suggested tints of black. Once you can make those come out on a screen, you can print the halftones you make in Photoshop.
If things take time to wash out, UV light is probably leaking through the positive. If you exposed for 20 minutes, the areas of the positive would wash out because they stopped UV light. You can only alter the exposure time once you have solved your opacity problem.
Put a dime on the positive the next time you expose. The dime will stop all light and is the best example of how the stencil should washout.
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How are you measuring? retired Ulano Technical Support Screen printing since 1979 - SGIA Academy Member
Maybe i am totally misunderstanding him but i beleive he is asking if he is supposed to use the Opacity Slider at the percents you listed above to get the greyscale ( white background as one layer and solid black image on another layer then change the opacity level of the black layer to X percent)
cant get halftones on ths screen 
This will help to harden the stencil more. Setting outside in the sunlight will help as well.
yeah yeah expose had to do it 
