Distance from exposure unit to washout

2171 Views 11 Replies 8 Participants Last post by Danny vital, Mar 28, 2014

ceaves

Discussion Starter · Mar 21, 2014

We've been printing now for several years using a home made exposure unit and Textil PV emulsion. We get good halftones at 30 seconds. I'm building my own shop now and I'm curious on the layout. My washout booth is going to be 15' or so away from the dark room. I'm nervous that with 30 second screens that by the time I get to the washout booth and water on the screen it will be overexposed.

I'd like to ask you guys 2 things:
1) What would a better emulsion be to use, I'm not against 2 minute burn times, seems to leave a little more margin for error.
2) Is the distance from dark room to washout that critical? Should I keep a water bottle in the dark room to wet down the screen before going to the washout?

Thanks a lot.

Chris

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StarDesigns

· #2 · Mar 21, 2014

I use WBP Hybrid emulsion and my exposure times average about 2 1/2 min. However, if you are happy with your current emulsion don't change.

We moved into our new space in December and it's set up is great. I have a good size paint room where I store all my paint and supplies. Just off the paint room is my dark room with exposure unit, washout booth and drying racks. I have two fluorescent light units over head (4 bulbs total) and I bought the yellow uv block tubes to put over the bulbs. I have plenty of light to work and no chance for UV's exposing my screens.

Mitchell - Star Designs
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Naptime

· #3 · Mar 21, 2014

1. when i first setup my shop, my exposure table was about 15' from my washout booth. i never had any issues getting the screen from the table to the water, and getting exposure in between.

2. when i reorganized my shop, i now have my washout booth, my dip tank, my soak tank, and my exposure unit all in a row. with my drying cabinet directly behind them.

question for you. is there some reason you can't move the exposure unit closer, since you are setting up the shop?

if not, head to home depot or lowes, and go to the brick/sand/concrete/garden area and look for a small, flat, black garden tray bin type of thing. I can take a picture if you need. I paid 15 bucks for it. it's basically a tupperware bin, large enough for a screen or two to lay flat in. works with my roller frames as well. it's about 4-5" deep. I keep it filled with water and right next to the exposure table.

screens come off the table, and into the soak tank for a full minute. out of the tank and into the washout booth, and washout takes about 15 seconds front and back. and into the cabinet.

this can be placed anywhere, right next to your exposure unit. once its wet, it will not expose on that walk to your washout booth.

otherwise, i would say your water bottle idea will work as well. ive done that.

sometimes in the winter, if i didnt feel like going through the hassle of turning the water on in the shop (i have to air blow the lines clear when i'm done to prevent freezing) and I just had 1 or 2 screens that need to be done right away, i would expose, spray with a water bottle, and then take them inside to washout in the shower. this was before i started using the soak tank.

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ceaves

Discussion Starter · #4 · Mar 22, 2014

Thanks, I had thought about getting something to dip the exposed screens in prior to washing out.

The reason for the distance is just the logistics of how we're setup, where the water/drain is and the such.

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sben763

· #5 · Mar 22, 2014

If there is no windows and you have florescent shop lights at ceiling height its not going to expose your screens. I have 1 window covered with black vinyl and 4 bulb florescent and a 2 bulb with cork screw florescent bulbs. I coat, line my films up to burn, put on exposure unit, take off, they sit out till I burn all the screens then I washout. All in florescent lighting no yellow light. Florescent lights unless daylight unfiltered black light or plant type put off almost no UV light. Then if you have the plastic cover over there will be 0 UV light getting to screens.

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Naptime

· #6 · Mar 22, 2014

I use incandescant bulbs and in the summer even coat and expose with garage door open.. just no direct sunlight on screens..

Some people make it seem more complicated and sensitive than it really is

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tpitman

· #7 · Mar 22, 2014

The only time I ever got "fogging" with Textil PV was when I turned on the white fluorescent light behind my washout sink thinking it couldn't possibly increase the exposure, but that was about 6 inches away. I use Saati Grafic HU42, which is a dual-cure, and shuffle from my exposure unit to my sink under overhead fluorescents, but I always keep the screen vertical and I have a bug light in my washout room. I don't think a walk the distance you're making will affect exposure, but I wouldn't hold it up towards your overhead lights looking to see if there's any trash that got caught in the emulsion.
The Saati Textil PV is an excellent emulsion for plastisol. I use the Grafic HU42 because it has some water resistance, reclaims flawlessly, holds excellent detail, and has a shelf life of over 60 days, which is good for a dual-cure. I buy quarts so none goes to waste because of age after mixing.

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CCClothing

· #8 · Mar 24, 2014

my washout is outside, so we have had to make some changes on how we actually washout. We burn, and right off the box, we spray the screen with water from a bottle. Spray front and back, open the door and wash out. Never had any issues. Takes about 30 seconds.

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jeron

· #9 · Mar 25, 2014

sben763 said:
If there is no windows and you have florescent shop lights at ceiling height its not going to expose your screens. I have 1 window covered with black vinyl and 4 bulb florescent and a 2 bulb with cork screw florescent bulbs. I coat, line my films up to burn, put on exposure unit, take off, they sit out till I burn all the screens then I washout. All in florescent lighting no yellow light. Florescent lights unless daylight unfiltered black light or plant type put off almost no UV light. Then if you have the plastic cover over there will be 0 UV light getting to screens.

what type of emulsion do you use??? I use Sattichem Grapic PU and its a photo-polymer. would you think it would still be safe to do that... I have 12 foot ceilings with about 10, 8 foot florescents up there.

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sben763

· #10 · Mar 25, 2014

jeron said:
what type of emulsion do you use??? I use Sattichem Grapic PU and its a photo-polymer. would you think it would still be safe to do that... I have 12 foot ceilings with about 10, 8 foot florescents up there.

I use either Saati Chem PHU or CCI HV(ryonet Hi-Fi) both are a photopolymer. At 12 ft even a SBQ emulsion would take hours to expose. A pure photopolymer would probably take days. Most over complicate the process. Take a coated screen and sit in just the Florescent area for 2 hrs. Then either washout or actually expose it. If you don't expose anything on it and it all washes out then it hasn't been exposed.

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jeron

· #11 · Mar 25, 2014

Ok thanks man, I am paranoid about it cause I'm new to screen printing and just always hear to do everything in safe light conditions... I'll have to test out a few screens and see how long they can sit out before starting to expose..

Thanks again

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Danny vital

· #12 · Mar 28, 2014

I use textil PV and was always super cautious about light..until I got a part time job at a local printer. He did all his coating and film on screen work in the complete open. I thought it was a bit extreme but he never had ANY issues. That being said, as long as you don't have some crazy lights on, I think you'll be fine.

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