# Emulsion washing out



## lilak (Dec 6, 2007)

Ok so I am totaly new at screen printing and have 1 BIIIIG problem. I coat the screen, expose it, then when I go to wash it out (with a shower head attachment) parts of the image wash out completely peeling off and rolling up, rendering the screen ruined.

How do I make this stop? Im about to pull my hair out!

HELP!

<3
Lili


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## Matto (Sep 28, 2007)

It is probably because of what you are using. A shower attachment really is not powerful enough to get the job done in time. The emulsion is very water sensative and the longer you keep it wet after exposure the more likely it will break down. Do yourself a favor and spend some money on an electric pressure washer in the 1200 to 1400psi range. 80-300 bucks depending on what you get. Then you can hit both sides of the screen to wet it down, let it sit for about 45 seconds then blow the image out and quickly dry it off. All in less than about 4 minutes.


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## lilak (Dec 6, 2007)

I would love to use a power washer, and am saving up to invest in one, but our problem is we have no spigot for a hose attachment. do you know if they are any power washer that do not need to be hooked up to a hose? the only ones I have used require a constant water feed, i.e. a hose. 

thanks!!


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## ChipShank (May 6, 2007)

At shops I've worked at since '89, I've used a regular garden hose & spray nozzle for rinsing out exposed screens and have never really had any issue with it. With most emulsions I've used over the years, water pressure from a hose with a nice wide fan type spray from the nozzle has worked very well. But everyone has their preferences and have learned to work with what they have...so it's tough to call from that angle.

Off the top of my head, I would likely guess that your screens are significantly under exposed. That would be the area that I would be inclined to look into first. If there is alot of emulsion running off of the well side (or inside) of the screen, I'd say that it is quite under exposed. A little should run off, but it shouldn't be excessive.

Other thoughts would be some sort of contamination from not being thoroughly reclaimed & degreased....Though that usually tends to be in patchy spots, not wide spread unless a really poor job of degreasing was done.

I would try adding a minute or two to your exposure time, just to see what you get. See if it makes a difference and work from there.


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## mosborne55 (Dec 7, 2007)

definitly sounds like underexposure. you can also check to see if the dwell side( inside or squeegee side as some call it) gets slimy, and if you notice a lot of suds on this side as you are rinsing the image out. if you are not already, you may want to try a pure photopolymer emulsion( one part no sensitizer) emulsion. these are usually faster exposing emulsions.


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## madaradio (Nov 12, 2007)

make sure to only use *cold* water! Even if you have a perfect exposer, hot water will ruin your screen.


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## RichardGreaves (Nov 7, 2006)

Emulsion is easy: If the emulsion washes out - it wasn't exposed enough. If it doesn't wash out, it was exposed and crosslinked somehow.

Water pressure will FORCE and tear the unexposed stencil. You could also smash open your front door rather than taking the time to use the key.

Properly exposed, you can soak a stencil for hours without harm (as we do in dip tanks) to dissolve the open areas. The whole point of cross linking the sensitizer is to make the exposed areas water resistant so they won't dissolve and rinse down the drain.

Yes, the most pleasant water temperature is 90°F. Hotter water will attack the cured stencil, colder water will just take longer to dissolve.

We have about 500 individual posts saying that the stencil washes out and the answer is always the same. Under exposed.


The number one job of EVERY screen maker is to learn to make an exposure test. Search this forum for "exposure test".


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## tman07 (Nov 14, 2007)

Not only exposure time BUT also the quality of the light source. If you are using a low UV output light source, you can expose it all day and it won't fully expose the emulsion.

LILI, What film or emulsion are you using? What light source are you using?


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## tomgrin (Oct 21, 2008)

RichardGreaves said:


> Emulsion is easy: If the emulsion washes out - it wasn't exposed enough. If it doesn't wash out, it was exposed and crosslinked somehow....
> 
> ...We have about 500 individual posts saying that the stencil washes out and the answer is always the same. Under exposed...


We went through the same thing. First we had a crappy light source (home-made reflector hung over top, etc.), now we have a pretty slick UV light box w/ a timer; (not a vacuum, maybe next year!). And we used crappy emulsion before we learned to use better stuff, so far Ulano dual-cure has been the best we've tried so far, haven't tried any of the pre-sensitized. Then even w/ a brand new scoop coater, we coated too thick, so that 5 minutes on our lightbox (which worked PERFECTLY for it's prior owners right up until the day before we first used it) was still 2-3 steps underexposed w/ the exposure charts on the sides. So we cranked it up, and got absolutely perfect screens where we coated thin enough, but where we overcoated, we still underexposed. 

Add to that not having a good inkjet, and using a laser printer (resolved yesterday), and believe me TS you're not alone. It's extremely frustrating but the exposure charts were the bottom line to helping us know what we were doing wrong. Good luck.


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## printing40years (Dec 27, 2008)

Next time double the amount of time under the light. Make sure the is no light creeping around to the back side, you need tight contact with the glass. If that works better then you are getting closer to the answer. If not you probably need to use a different brand of emulsion or different stronger light source. You can also move the light closer to the glass.

Bryant


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## Reinhard (Dec 30, 2008)

There are a few things to consider:
1. The type and age of the emulsion you're using. Emulsion has a shelf-life, so it might not expose appropriately if it is too old. 
2. The emulsion might not have been sensitized appropriately or been exposed during the mixing process.
3. The screens were not degreased.
4. The light source is not strong enough or you need more exposure time to make up for the strength of the light source.
5. Water pressure might be too high. 

It would be helpful if you added information about what you are using and how you did the exposure (i.e time, distance from light source, etc.)

I've had similar problems and in most cases, I had underexposed the screen and in some cases the wash-out pressure was too high. 

I used a shower extension first and this literally took me about an hour to wash the screens out. I then upgraded to a pressure washer, but using it without turning it on (i.e just using the water pressure coming into the nozzle attachment) and it was even too strong sometimes and washed out the emulsion, but I'm getting the wash-out done in about 10 minutes now. 
My suggestion is that a pressure washer is not necessary, but an extension that helps you control the spray is better then a shower attachment. 

If you give more info we could probably provide more tips.

Good luck


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## tomgrin (Oct 21, 2008)

Every shop we know eventually gets a pressure washer, but TONS of people use the garden hose method. Although we are waiting for a sweet craigslist deal ($50 for a like new 1550psi pressure washer from someone who is moving and will be back next week to get it out of storage!), we've had very good success with a garden hose. In our case (the particular type of emulsion we use, Ulano Dual) and the thickness of it, etc., I doubt we'd ever need to turn the pressure washer even on accept to reclaim screens which should blow mostly straight out. But the water pressure through it w/o the pressure on should be mint and I know a lot of shops who do exactly that, which in effect, is exactly the same as a garden hose w/ a GOOD nozzle. 

What we recently upgraded to that was even better, was (blatant plug) a Victory Factory spray hose w/ nozzle for just $10!!! It jets out a much faster spray than most nozzles we've used before, and it also fans out for a nice soft larger mist too. It was cheap, and the trick that seems to do it for us, is to mist both sides quickly, and let it sit for 30-45 seconds. Then come back and QUICKLY blow out the screen; watching to not overpush any small detail out simply from the pressure or staying under the spray too long which in itself will eventually break down small stencil details. Someone said it best in another thread, try to expose (no pun intended) your screens to as little water as necessary to clean it out in it's first wash-out after exposure. Once it's dried/cured, it should be water safe for the most part. But if you're sitting under the water for 5-10+ minutes (or 20+ like our failed first attempts in the early days), your likely causing it to degrade just from the time under the water. 

Some of the pros might be able to tip you a bit on some additives and other processes that protect/extend emulsion, so ask around. There's really good people on this board willing to help. We'd have been lost 10x over already without it. Good luck!


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## RichardGreaves (Nov 7, 2006)

It is the primary job of the screen maker to learn how to judge exposure. 

Invisible UV energy reacts with emulsion sensitizer and hardens the stencil so it won't dissolve with water and rinse down the drain. You block UV energy with a positive during exposure so the image area dissolves when you develop the stencil with water. 

Don't waste time guessing - use a US$10 Stouffer 21 step transmission guide and *measure*. How much is your time worth?










It's a 5.5" long photo positive that's opaque at one end and clear at the other with 21 steps in between. With one exposure, you simulate 21 different exposures. Aim for a Solid Step 7 where the 7th step hardens enough so it won't dissolve and rinse down the drain.











For more details read:
http://www.ulano.com/FAQ/FAQexposure.htm#Q1


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## tomgrin (Oct 21, 2008)

Greaves to the rescue once again! Thanks man! We put two exposure strips on our 20x24 screens, one on each side (and at other times trying the ends, etc.) and we found at least a 1-2 step difference in exposure. 

We've concluded (curious on the pro's input) that either we're still not pushing hard enough or sliding vertical fast enough w/ our nice new scoop coater (even though we're mindful of it, possibly overcoating the screens with emulsion... just seems like the optimum amount on our 156mesh w/ Ulano dual is SO transparent of a layer); or that the bulbs in our exposure unit aren't event from one side to the other. 

So.. not for nothing, but if you're just finding these threads and having these issues, don't be cheap, buy 2 step exposure strips and drop one on each side. It really helped us at least start to understand what was going on --- and we're still learning.


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## ProTipKnit (Dec 22, 2017)

can i resurface this old thread?
ive ruined all of my screens over and over again by not being able to reclaim my screens. my emulsion gets stuck on all my screens, ive pressure washed, bleached and used emulsion remover. you name it, ive done it.
ive tried so many different experiments, times and ways to get the emulsion off. i feel like i have tried it alll other than changing my emulsion... so my latest experiment was exposing on different times and then not exposing at all, only coating.
i degrease thoroughly, dry the screens, then i coat the screens and store in my very dark very light sensitive storage unit. ive been told that its possible that the emulsion isnt dry before i expose so i took the extra step and let them sit for about 4 days before i even look at them and start to work with them. i have also changed that variable of days to see if maybe they were sitting around for too long.
ive also been told that my light source (500 W halogen lamp) could burn on my emulsion.
so i used a less extreme light source to expose, with all different and ranging exposure times. to no avail.
so my latest experiment was to expose all my screens to different times but to leave 1 screen out to no exposure to see if maybe it was my emulsion... i get my emulsion out with about a 10 minute scrub, im covered in water, i had to use 3 different scrubbers and it was nothing like i see on youtube tutorials with people using almost the same exact set up as me, other than emulsion.
im under suspicion that i was sold a bad batch of emulsion. ive stored in a cool dark dry place as recommended. i spotted some white mold looking stuff inside the emulsion but then was reassured that was nothing to worry about. my emulsion is currently SAATI TEXTIL PHU BLUE. is there anyone out there can help this money pit of a business i have seem to stumble across and give me some answers... does that seem wrong to you? should it really be that hard to scrub emulsion that hasnt even been exposed off of my screen? i have done everything i can, wasted a lot of money time and effort, i am almost at my breaking point of giving up. i understand this comes with anything new but, i just dont have it in my anymore.


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## mocapartizan (Jan 21, 2010)

Im not new in screenprinting but Im frequently moving and changing my exposure system. Now I got exposed screen with several motives. How can I preserve those that are left (straighten tham) since my previous motives are distroyed after 300 strokes on paper with 85 sh squegee? I tryed to expose screen again but looks it didn do the job. Emulsion is Zero In Universal - Argon.
Thank you


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