# How Long Do I Have Before Wash-Out After Burning Screen



## HellaUmbrellas (Jul 23, 2010)

Hi, I run a small screen printing shop - Not a Newbie...

My Question:

We are re-organizing our space. We have a brand new washout booth capable of washing out 4 screens at once.

I am wondering if any experienced printers have input: If burn all our screens at once in the darkroom and stack the EXPOSED screens in a light safe environment, then bring all to washout booth at once.

What I am concerned about in particular (since I am pretty sure I can get away doing this with simple spot color images) is how this may or may not affect halftones... I have also heard of immersing screens in water to freeze the exposure process... would a dip bucket in the darkroom help at all?

Thanks for the help!
Reuben


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## ole Jobe (Jun 16, 2009)

The exposed screen may be kept indefinitely as long as it is not exposed to UV light, excessive heat or moisture. I have burned up to a dozen screens while waiting for the water to be turned back on and have kept them a couple of days before washout. God Bless.


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## whimsywhit (May 25, 2009)

Ok, while we are on the subject I have a quick question. I know it's a big no-no for light to hit the screens, and we do have an appropriate lighting in the room we burn screens in, but I have never been told what happens if the exposed screen is hit by the light. So, does it completely ruin the screen? Does the screen get over exposed?


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## BroJames (Jul 8, 2008)

Reuben, why do you need to *"bring all to washout booth at once"* ? Why not use "safe lights" in your washout area. 



ole Jobe said:


> The *exposed screen may be kept indefinitely* as long as it is not exposed to UV light, excessive heat or moisture. I have burned up to a dozen screens while waiting for the water to be turned back on and have kept them a couple of days before washout. God Bless.


I am not really sure how the unexposed part of a detailed image will wash out after a couple of months in storage but a few days should be OK.




whimsywhit said:


> Ok, while we are on the subject I have a quick question. I know it's a big no-no for light to hit the screens, and we do have an appropriate lighting in the room we burn screens in, but I have never been told what happens if the exposed screen is hit by the light. So, does it completely ruin the screen? Does the screen get over exposed?


If you are talking about household fluorescent or CFLs then a brief exposure of say 5-10 minutes, even a little longer should be OK. I have accidentally left a 5w CFL open for about 45-60 minutes while drying coated screens and the screen was later exposed and wash out OK. 

Even if we talk about UV rich sunlight, a couple of seconds should still be OK. I have exposed images using sunlight and unconsciously flipped the print side of the screen towards the sun but the image washed out fine.


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## whimsywhit (May 25, 2009)

BroJames said:


> Reuben, why do you need to *"bring all to washout booth at once"* ? Why not use "safe lights" in your washout area.
> 
> 
> 
> ...



Ok, that's good. I was just curious, because we have a bathroom in the same area and sometimes the door may open and someone come out while we have a screen in there. Also, I was just curious what problem it may cause because our screens just do weird things sometimes!


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## HellaUmbrellas (Jul 23, 2010)

Thanks guys... It seems like that will be the plan, expose all at once, and wash out all at once - save some walking back and forth.

@ BroJames - Our washout booth is not in the same area as our darkroom, so at some point we have to walk the screens through the flourescent production floor. Never been a problem.

@ whimsywhit - _"Also, I was just curious what problem it may cause because our screens just do weird things sometimes!"_

...Honestly, I think the two most important things to invest in if you are at all serious about screen printing, is a decent dryer and a decent exposure unit - Exposure unit first. You can print on a freakin' table top, as long as your screen is coated and burned properly, and you can dry the shirt well.

If you want to take us through your screen prep steps, I'm sure someone can help figure out why your screens act weird....


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## Ken Styles (Mar 16, 2006)

You can also keep a spray bottle filled with cool water and stray it down while the other screen is exposing. That would stop the exposure process as well.


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## whimsywhit (May 25, 2009)

Well, we have a table top with the elbow that we put the screen up against to make sure it is square, use the t-square to line the art up, put the screen on the glass top face down, run the string over the edge, turn the vacuum and light on, and burn the screen. Sometimes though, it could be an hour or two before we actually get to washing it out. The washout room, however, does have regular light bulbs in it. They may even be fluorescent, I'm not sure. And the main problem is the white screen. We burn a 155 for our white, we set it up on the machine, he starts printing away, and after 12 shirts it seems like white is stuck in the screen. Like it gobbed up in just this one spot. Different spots on different screens. I've checked the squeegee for nicks, I've adjusted and readjusted pressure, I've added reducer. Still, every 12-20 shirts, it's like a small area gets gooked up. I thought the flash unit was drying the white in the screen, but after watching closely, it gets that way before I ever flash. The only think I can figure it something is going wrong in the exposure process, but everything is pretty much by the book. And it's never the whole image. Always just a quarter size spot.


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## BroJames (Jul 8, 2008)

HellaUmbrellas said:


> . . .
> 
> @ BroJames - Our washout booth is not in the same area as our darkroom, so at some point we have to walk the screens through the flourescent production floor. Never been a problem.
> ...
> ..Honestly, I think the two most important things to invest in if you are at all serious about screen printing, is a decent dryer and a decent exposure unit - Exposure unit first. You can print on a freakin' table top, as long as your screen is coated and burned properly, and you can dry the shirt well.


If passing by the production floor with fluorescent is the concern. I have seen people exposed CMYK screens one after the other, stand the exposed screens under a regular 30" or so high table, then after all are exposed (about 15-20 minutes or so), take the screens to the next room for wash out. I believe there are a pair of 40w fluorescent tube overhead(am sure of at least 1 40w). Light still shines under a good part of the table at an angle.

As to "Immersing screens in water to freeze the exposure process", moistening it is enough to drastically slow down any post exposure.


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## slidways (Dec 26, 2009)

whimsywhit said:


> Ok, while we are on the subject I have a quick question. I know it's a big no-no for light to hit the screens, and we do have an appropriate lighting in the room we burn screens in, but I have never been told what happens if the exposed screen is hit by the light. So, does it completely ruin the screen? Does the screen get over exposed?


if you burn a screen, the image is still light sensitive, so if light hits it, it will expose the image you took the time to burn into the screen, so it wont wash out.


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## BroJames (Jul 8, 2008)

whimsywhit said:


> Ok, while we are on the subject I have a quick question. I know it's a big no-no for light to hit the screens, and we do have an appropriate lighting in the room we burn screens in, but I have never been told what happens if the exposed screen is hit by the light. So, does it completely ruin the screen? Does the screen get over exposed?



If we are talking about a 20w household fluorescent on the ceiling or CFLs and unexposed screens, a few minutes of "exposure" won't really matter. However, prolonged exposure may result in slight exposure which may affect(or damage) subsequent exposures but if you will be washing the slightly exposed screens you should still get a complete washout just by using water. I do not know what will happen in 3 hours or more but it will take more than that for a fluorescent 10 ft high to expose (or overexpose) a screen at table height.

PS: For coated or exposed screens, a few short minutes of ceiling fluorescent should not have any detrimental effect but the safety rule remains - stay away from lights.


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## jsf (Aug 4, 2009)

slidways said:


> if you burn a screen, the image is still light sensitive, so if light hits it, it will expose the image you took the time to burn into the screen, so it wont wash out.



Yup. Specially if it is hit by the rays of the sun or bright light . 

You may want to cover your newly exposed screen with a blanket or anything can cover your exposed design while in travel.....


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## HellaUmbrellas (Jul 23, 2010)

@BroJames - _"prolonged exposure may result in slight exposure which may affect(or damage) subsequent_ exposures" Can you explain further? I also have no problem washing out screens that have been hit with a little light... but it can affect future washouts?

@WhimseyWhit - That sounds like one of those headaches... I assume you are using different screens every time. Only things I can think of:

1) Screens are not de-greased properly... make sure you are fully washing out degreaser and not leaving any soapy residue.
2) Try a different brand of white. I have used whites in the past which totally clog in the screen. I use Wilflex Bright Tiger for all-purpose, and Rutland Snap White for Auto...

...other than that good luck!


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## BroJames (Jul 8, 2008)

HellaUmbrellas said:


> @BroJames - _"*prolonged exposure* may result in *slight exposure* which *may* affect(or damage) subsequent_ exposures" Can you explain further? I also have no problem washing out screens that have been hit with a little light... but it can affect future washouts? . . .


Some 20-25w CFLs about 12" high can expose emulsions in about 30 minutes I think so that's a disclaimer of sorts.


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