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Discussion Starter · #1 ·
Need some help ok so when i burn half tones I cant seem to blow it out properly it keeps some of the dots and blows out most of them as well small print like if i want to print out tagless tags half of the print blows out some washes out and some the image shows up but i cant wash it out. I have a exposure unit it has 8 light bulbs and i believe they are 15w each and im using Murakami HV emulsion. When i burn my halftones its usually for about 2 to 2 1/2 minutes and for everything else about 4:30 to 5 mins. I double the film as well...can anybody give me any advice or help me out please???
 

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ok im using 305?? 2 mins too low?
OK, 305 is just fine. Now, it also can be resulting from under-exposure. My lightbox contains 4 units of 18w blue flourescent lamps and I normally do my exposures for 90 secs.

Before I had my blue bulbs, 4pcs of 20w household florescents was installed and it takes me about 5-6mins of perfect exposure.

The height from source light to glass is about 6-7 inches.

Now, I don't know if your 8x15w light source will give enough UV exposure to your emulsion. Better to take a step wedge test (30 secs time steps) and see what is the exact exposure for your emulsion.

Good luck.
 

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Discussion Starter · #7 ·
OK, 305 is just fine. Now, it also can be resulting from under-exposure. My lightbox contains 4 units of 18w blue flourescent lamps and I normally do my exposures for 90 secs.

Before I had my blue bulbs, 4pcs of 20w household florescents was installed and it takes me about 5-6mins of perfect exposure.

The height from source light to glass is about 6-7 inches.

Now, I don't know if your 8x15w light source will give enough UV exposure to your emulsion. Better to take a step wedge test (30 secs time steps) and see what is the exact exposure for your emulsion.

Good luck.
How do i do one of them tests? and just by saying you think I should do a 90 second exposure or 5 mins?
 

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So how are you determining your times, mesh counts, emulsion etc? Sounds like you're randomly trying different things in hopes of success.
The whole process isn't just arbitrary shots in the dark. I suggest you stop, go back and study and get a comfortable understanding of all the elements of the screen printing process and how they go together. A comprehensive instructional DVD or book would be a good place to start. It will probably eliminate a lot of frustration and guess work.
 

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Discussion Starter · #10 ·
So how are you determining your times, mesh counts, emulsion etc? Sounds like you're randomly trying different things in hopes of success.
The whole process isn't just arbitrary shots in the dark. I suggest you stop, go back and study and get a comfortable understanding of all the elements of the screen printing process and how they go together. A comprehensive instructional DVD or book would be a good place to start. It will probably eliminate a lot of frustration and guess work.
Well my business partner was into it before me and he passed on all his info to me that's what I'm going by...
 

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Things to check:
Is your film dark enough?
Have you used a test film like the Chromaline test film to dial in your exposure on a 305?
Sounds like not dark enough film or underexposure.
Try an insane time and see what happens on washout. When you can't wash it out, then start backing off your exposure time until the pressure washer takes it out with a little effort.
 

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You said you were doubling up your film? That could be the problem. Are you using clear film for an inkjet or vellum. If your using vellum I'd suggest switching to clear film if you want to do half tones. Someone else mentioned also whether your film is dark enough. How dark are your regular solid positives?
 

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Discussion Starter · #14 ·
Things to check:
Is your film dark enough?
Have you used a test film like the Chromaline test film to dial in your exposure on a 305?
Sounds like not dark enough film or underexposure.
Try an insane time and see what happens on washout. When you can't wash it out, then start backing off your exposure time until the pressure washer takes it out with a little effort.
My printer for some reason doesn't print extra dark so I always have to double up the films, and no I haven't run any kind of test when I do 1 and 1/2 minute it comes out slimy when I do 5 it doesn't wash off right away...I know it should and when I do 2 mins it does wash off easier them 5, but it breaks the image also
 

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Discussion Starter · #15 ·
You said you were doubling up your film? That could be the problem. Are you using clear film for an inkjet or vellum. If your using vellum I'd suggest switching to clear film if you want to do half tones. Someone else mentioned also whether your film is dark enough. How dark are your regular solid positives?
Yeuwell I double them up
Because my printer won't print up dark enough film....and I'm using clear film...my regular ones aren't super dark like they should be.
 

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Yeuwell I double them up
Because my printer won't print up dark enough film....and I'm using clear film...my regular ones aren't super dark like they should be.

If it is a film issue, try printing your design on vellum. You do not have to double it and I presume it is just a one color job so no worries. If you are not that satisfied with your printer with the black ink, try printing it with "RUBY" color.

These things are all suggestion that you may not do and use. Hence, do not confuse yourself.

Good luck.
 

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Discussion Starter · #17 ·
If it is a film issue, try printing your design on vellum. You do not have to double it and I presume it is just a one color job so no worries. If you are not that satisfied with your printer with the black ink, try printing it with "RUBY" color.

These things are all suggestion that you may not do and use. Hence, do not confuse yourself.

Good luck.
What's vellum? And what's ruby color?
 

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Are you using an ink jet printer. We use an epson wf1100 at work. It took a while to get the settings right and we use clear film also. I can't imagine you'll ever get effective half tones doubling up your film. Are you printing from illustrator and what type of printer are you using?
 
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