# Printing halftones & washing out screens



## buckcreek (Aug 13, 2007)

I used the gradient tool in Photoshop to fill in 3 horses in a design. One is dark , one medium and one light. I exposed the screen for 4 1/2 minutes using the florescent tubes and when I tried to wash out the screen the darker horse washed out pretty good but not completely. The other two didn't do well at all. I'm thinking that the very light parts of the design might have been totally exposed since the dots were so few. I also might have exposed it for too long. Any ideas?

Also, I want to print halftones but I'm not doing four color process so is the information about the shape, frequency and angle of the dots important? I'm still trying to understand these halftones and how to print them. Any help would be appreciated.
Thanks


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## amp267 (Oct 11, 2006)

just to add to that, how did you coat your screen, in what lighting did you coat it & wash it off in. what did you use to wash it off, hose pressure, or power washer with power off. what mesh did you use, what emulsion did you use. and everything else mentioned above.


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## buckcreek (Aug 13, 2007)

I am printing on Fast Positive Water Proof film with an Epson 1800 printer using Fast Rip.
I am using a 110 screen with Ulano QTX emulsion. The exposure unit has 6 florescent tubes and has glass over them. I tape the film positive to the substrate side of the screen and put it down facing the light
I put foam and wood over it with 4 gallon containers of water to hold the film down good. I also use a yellow light bulb to protect the emulsion.

When I expose a screen with just black on it I don't have a problem. I looked at the dots with a magnifing glass and they are all black. 

When I printed I used FastRIP 720 TD-55lpi for the print mode. On the halftone screen for cyan is used 54.9 freq. 108.4 degrees and the shape for all was elipse. The magenta was 47.4 at 161.6 degrees, the yellow was 50 at 90 degrees and the black was 53 at 45 degrees. Since I am only using black does the settings for the other colors make any difference?


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## Celtic (Feb 19, 2008)

buckcreek said:


> I am printing on Fast Positive Water Proof film with an Epson 1800 printer using Fast Rip.
> I am using a 110 screen with Ulano QTX emulsion. The exposure unit has 6 florescent tubes and has glass over them. I tape the film positive to the substrate side of the screen and put it down facing the light
> I put foam and wood over it with 4 gallon containers of water to hold the film down good. I also use a yellow light bulb to protect the emulsion.
> 
> ...


 

You'll definitely have an issue using a 110 mesh screen to do halftones. 
You want to use a 230-305.
Otherwise, what's happening is that your halftones are just falling out. They are too small for the mesh of a 110.


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## amp267 (Oct 11, 2006)

Celtic said:


> You'll definitely have an issue using a 110 mesh screen to do halftones.
> You want to use a 230-305.
> Otherwise, what's happening is that your halftones are just falling out. They are too small for the mesh of a 110.


i second that, i have even used 195 screens with bad results, nothing lower than 230 for me


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## Solmu (Aug 15, 2005)

Celtic said:


> You'll definitely have an issue using a 110 mesh screen to do halftones.


I wouldn't say you'll definitely have a problem, but rather that it definitely depends on what you're doing. I've used a 110 for half-tones with good results - for textile printing that's often an adequate half-tone. It's not like we're talking a smooth high resolution surface, or four colour process here.


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## frankiko (Jun 13, 2008)

i find this formulas are very good to me.
1) if you want to find out what LPI need for your artwork:::
MESH COUNT divided by 3.5 (or 4) = LPI (for example: 110mesh / 3.5 = 31 lpi)
2) if you want to find out what screen mesh you need:::
LPI multiplied by 3.5 (or 4) = MESH COUNT (for example: 45 lpi * 3.5 = 157 mesh (or any mesh count close to that)


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## buckcreek (Aug 13, 2007)

I believe I did have color checked when I went to print even though I only used black for the design. That and using the 110 mesh sounds like something I need to change. I appreciate all your comments and would like to say it is great to have a place to ask questions when you are new and don't know what you are doing wrong. That can be so frustrating, I didn't know how involved screen printing could be but it's very rewarding when you do it right. Thanks.


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## spankthafunk (Apr 9, 2007)

this is some great information. I haven't used high mesh counts yet but I think I might give that and this a try. Thanks for all the info everyone.


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## CR Graphics (May 2, 2012)

I am in need of some help here, Please!!!!
Here goes, I have spent hours today trying to burn and washout screens, some r just 110 mesh for underbase and some are 305 mesh with half tones. I have never had this problem before with my 110 screens. I use the ulano EZ film emulsion. 30 & 50. Today I was going to try to do a cmyk design, but I can't even get a darn screen burned and washed out. This is what is happening: Burn as usual go to washout booth use very soft water pressure and when the emulsion started to come off it looks slimy. No resolved like usual. I have messed up so much emulsion. Can somebody please tell me what the problem is?
Thanks,
Christie


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## sben763 (May 17, 2009)

What type of exposure unit? If unfiltered blacklights or daylight may be time for a change. Try adding time if it slimy its under exposed or too much humidity. Could be bad film, but can't help ya there I only use liquid emulsion and only used film 1-2 times.


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## CR Graphics (May 2, 2012)

Thanks for your quick reply,
I never thought of humidity, that just might be the problem. We have had lots of rain in the last week and humidity has been very high and I have not had the air on. I turned on the air last night so let see if maybe it took out all of the bad stuff.
Thanks again,
Christie


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## 20vK (Jul 9, 2011)

It takes my liquid emulsion 24 hours to dry here in the Caribbean. You can normally tell if it is dry or not, because either there is a dark patch where it is still damp, (far too damp and positives will stick to it and be ruined), or it sticks to the glass on my vacuum exposure unit. Coming into summer and hurricane season, I've already noticed the humidity kicking in.

For halftones you you should create several boxes, each with a known halftone % in so you can see what range of halftones you can capture. If you don't know your upper and lower limit, then you are missing out a large part of halftone printing and artwork compensation and design.

For each mesh screen and each coating variation, you want to do a range of tests with your halftone boxes, to see what the perfect exposure times are for capturing a wide range of well exposed halftones that wash out well. Start off at 0, 3% 5%, 10%, 15%, 20%, 30%. 40% upto 75%, then 80%, 85%, 90%, 95%, 98% 100%

You want to really be aiming for at least 5% through to 95% for single source exposure units. You are looking for consistent halftone pattern that does not blow out easily. THis will give you the most consistent prints


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## CR Graphics (May 2, 2012)

WoW, what a mind blower. I am very new to this cmyk stuff that I really do not understand to much of what u have said. Please forgive the newbee.
I had a guy do some shirts for me because I did not know how to do it, he sent me the files,(separation) and told me to use 53 line and black 45
yellow 90
mag 75
cyan 15
so that is how i printed the films. I really do not understand any of this, Just did what he told me to do. But for the life of me I can't get the burned screens to wash out, without the dots coming off too.


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## SammySk8 (May 13, 2012)

Hey 20vK what part of the caribbean are you in?


Sammy Vazquez


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