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screen printing => Equipment => Topic started by: jvanick on November 06, 2013, 07:55:23 AM

Title: Post-exposure dip tank?
Post by: jvanick on November 06, 2013, 07:55:23 AM
I've heard a few people here talking about post-exposure diptanks...

I assume you're just using a standard tank with water in it instead of wetting the screens with a hose.

What's the pros and cons of doing this instead of the hose?

I have the opportunity to grab a tank for dirt cheap and was thinking it might make life easier...
Title: Re: Post-exposure dip tank?
Post by: tonypep on November 06, 2013, 08:23:59 AM
Yes some people do this. Obviously the water will pre-soften the exposed portions of the screen. Not a bad idea if you are not pressure rinsing. Can cause bottlenecks for some for others its a non issue.
Title: Re: Post-exposure dip tank?
Post by: bimmridder on November 06, 2013, 08:48:34 AM
Tony, here in our shop (and this is what works for us, not necessarily anyone else) we use a dip tank and pressure washer (750 psi). I've actually unintentionally left screens in the tank over night and still use pressure washer and have great screens. We do all our screens like this, from specialty screens (26tpi) to 4CP (355tpi). Not saying it will work for anyone else, but it does for us.
Title: Re: Post-exposure dip tank?
Post by: screenprintguy on November 06, 2013, 09:00:58 AM
Watching Bimmrider and Greg Kitsen doing this, we started doing it 2 years ago and it speeds up our process, as the wet softened image basically falls out in the wash out booth rather then standing there holding a hose or blasting with a pressure washer to soften the image. Its a great addition to our exposure process!
Title: Re: Post-exposure dip tank?
Post by: tonypep on November 06, 2013, 09:29:59 AM
Thats how we did it in St Thomas. One auto, 2 man shop. They would soak while presses ran.
Title: Re: Post-exposure dip tank?
Post by: Gilligan on November 06, 2013, 09:38:23 AM
My guy LOVES it... You can literally rub the image off with your fingers.

Only downside I see is that my guy leaves them in so long some emulsion is coming off in the tank... It just makes the water kind of gross, nothing else bad about it.
Title: Re: Post-exposure dip tank?
Post by: GaryG on November 06, 2013, 09:50:13 AM
Thats how we did it in St Thomas. One auto, 2 man shop. They would soak while presses ran.

Now there's a dream job!
Soaking in the tank, and soaking in the sun!! 8)

In smaller shops like ours soaking is a multi-tasking benefit
while other tasks are being done.
Title: Re: Post-exposure dip tank?
Post by: alan802 on November 06, 2013, 10:04:15 AM
We do it and although it's not technically faster, while the screen is soaking for a few minutes you're doing other tasks like Gary said.  Instead of standing there spraying the screen with the pressure washer, you can be burning more screens.  Some higher mesh screens with thin stencils will literally spray out with a spray bottle after soaking for a few minutes.  It's allowed us to hold a little more detail since very little pressure is needed to knock the stencil out and the finer halftones don't get blown out.  We can hold a few percentage points smaller in halftone dots by pre-soaking/post exposure.
Title: Re: Post-exposure dip tank?
Post by: screenprintguy on November 06, 2013, 10:11:00 AM
I get a nice flow going, doing 2 screens at a time, after they start coming off of the I-Image CTS, 2 go in the tri-light, supper fast to expose, go right in the water, pop 2 more screens in the tri-light, check my CTS, pop in a new screen there, hit print, tri-light's done, swap out the dunked screens, pop in two more frames in the tri-light, and keep on rockin. There is a cool shop in Tampa, Class B, they just moved into a new giiiiiiiinormise space, huge front of house, I didn't even get to see that, but the production manager took me on a shop tour. They run, if I can remember, 6 or 8 autos, they had at that time Sportsman ex's and some older lawsons, tons of small 24 piece orders. They  have a nice huge dedicated clean aired DTG room, and the Imaging room is to die for. A screen printers dream and a half. Totally sealed up, keep in mind all new construction, so it all looks really sweet too, like show room look there. In the imaging room, one girl running it, doing 200-300 screens a day on her own. She as a brand new kiwo CTS, brand new kiwo screen coater that coats, I think 4 frames at a time, everything is 23x31 there. Brand new Douthit cts exposure unit. I have a feeling, if Rich, hint hint hint, sent someone over there like Ron, hint hint, lol, they would swap out of that into a D-scan. And then finally they had this cool CCI stainless tank and rinse thing made. It can hold up to like 15 or 20 frames along these rails, you slide the exposed screens down in there and there is a foot pedal switch that activates an agitator, and at the far end is a rinse booth with just a hose and standard water pressure to rinse. This girl gets moving along and her system is very smooth. That big CCI thing though, is about 12 feet long, but with the agitated water, the images are just about gone when she lifts a screen for final rinse. I would think, an agitated tank alone, and then that new M&R auto rinse booth would be the bomb in that system, but like I said, it's a very impressive room that keeps 1 employee rocking busy 8 hours a day cranking out perfect screens. I must have seen 50 or so rolling screen racks full of newman frames, ready for production racks, and then post production ready for de-ink racks. Cool place and cool production manager to take me on a tour. I'd eventually love to have my Imaging room which is now my office desk and mac with my I-image, with an adjacent dark room for easy access screen storage expanded into a larger room with a D-scan in the room next to the CTS, and the Auto Rinse booth, maybe build a clean air de-humidifiying room to then put the rinsed screens for quick drying. That would be sweet!
Title: Re: Post-exposure dip tank?
Post by: jvanick on November 06, 2013, 10:45:57 AM
cool... I'm going to check it out later today... if it looks good, I'm buying, even if not, sounds like even a brand new one might not be too bad an idea..
Title: Re: Post-exposure dip tank?
Post by: tonypep on November 06, 2013, 11:03:42 AM
Brannon may have a used one.......lil bird told me
Title: Re: Post-exposure dip tank?
Post by: ericheartsu on November 06, 2013, 11:21:23 AM
we also do this. Like everyone else said, it just seems to help a bit.

We expose, put two screens in, set up the next screens in the exposure unit, and then rinse while it's exposing.
Title: Re: Post-exposure dip tank?
Post by: screenprintguy on November 06, 2013, 11:41:41 AM
We have a petroleum contractor customer that had a fiberglass tank that normally goes underground under gas pumps at the gas station that didn't fit on a job, and he gave it to us. It's a bit bigger than a standard dip tank, 100 gals, but it's perfect for the presoak, I have an air line weighted down at the bottom, and attached to a small air pump that agitates the crap out of the water, it's actually a bit too much, makes the water foam up lol, but when you pull out a screen, there is almost no emulsion left in the image area from the agitated water.

Hey guys using them, how often are you changing your water, I haven't changed ours in a while, dam near a year now, I put a cup of bleach in the water every friday night to keep the water from getting nasty, doesn't effect t he stencils at all, keep in mind it's 100 gals of water as well, but I imagine all of that unexposed emulsion eventually builds up in there. Plus with us using the CTS, the water immediately turned black from the ink coming off the image in the soak. Just curious.
Title: Re: Post-exposure dip tank?
Post by: tancehughes on November 06, 2013, 11:52:03 AM
We use one and it helps us multi task better, I highly recommend it. Doesn't hurt the screens if they stay overnight in the tank, although we don't make a habit of that.
Title: Re: Post-exposure dip tank?
Post by: alan802 on November 06, 2013, 12:01:36 PM
I've been changing out the water every couple weeks.  Ours is a smaller unit that only fits two 23x31 screens so I can pick it up and drain it easily unlike the reclaiming dip tank that takes some serious muscle to move around.
Title: Re: Post-exposure dip tank?
Post by: ebscreen on November 06, 2013, 12:28:18 PM
Unlike an emulsion removing dip tank, the contents of this one are the price of water.
Use anything you can fit screens in comfortably. Ours happens to be a stainless tank
for some reason, holds 8 screens or so, tap at the bottom to change the water when necessary.
Gets stinky during the summer every month or so.

A soak is a heck of a lot more consistent than a spray with a hose.
Title: Re: Post-exposure dip tank?
Post by: kingscreen on November 06, 2013, 12:42:16 PM
We use one. It's definitely more of a luxury than a necessity. We typically fill ours up with about 5 screens at a time while burning loads of screens and then wash out as we're adding new ones in the water tank. It really just creates a cycle and gives the employee something to do while waiting on a screen to burn. It also makes wash out a lot easier and you don't have to drill down on a screen with a pressure washer.
Title: Re: Post-exposure dip tank?
Post by: tonypep on November 06, 2013, 12:55:48 PM
Similar to how I make Solar plates at home for intaglio printing. Essentially cap film laminated on thin aluminium. Exposed in the sun using 3/4" glass. Sit in water tray for 1 hr. Finally plate is gently brushed with brushes or seagull feather. Sounds ghetto but when done right extremely professional results may be achieved.
Title: Re: Post-exposure dip tank?
Post by: Gilligan on November 06, 2013, 01:03:46 PM
I've been thinking about a black tank on the roof and circulating water through it.  Will provide agitation as well as warm water (for free).

Any thoughts?
Title: Re: Post-exposure dip tank?
Post by: screenprintguy on November 06, 2013, 01:42:52 PM
I've been changing out the water every couple weeks.  Ours is a smaller unit that only fits two 23x31 screens so I can pick it up and drain it easily unlike the reclaiming dip tank that takes some serious muscle to move around.

That's nice, if it wasn't that the one I'm using wasn't free, I'd go for a smaller easier to move around tank. I actually have ours sitting on top of one of those home depot style heavy duty flat bed carts, so we can roll it out or move it easier if we need to. When it was in the back of the shop, it just sat on the floor and i had to run a huge pool drain hose outside and hook it up to a sump pump to empty it lol. Think its time to dump this one, saw some slime in it today, don't need some weird supper bug mutating in it lol
Title: Re: Post-exposure dip tank?
Post by: GKitson on November 06, 2013, 02:27:37 PM
Love the post exposure dip tank, many have seen this video of how we use the tank with CTS Exposure and washout, but here it is again.

However, I am thinking I am going to have to re-think the work flow once the LED's are added. May involve some crowbars and such stuff ...

~Kitson

http://tinyurl.com/kfdyqg9 (http://tinyurl.com/kfdyqg9)

Title: Re: Post-exposure dip tank?
Post by: screenprintguy on November 06, 2013, 03:40:21 PM
Greg's always coming up with cool ideas!!!

Greg, that hose going into your water tank, is that a recirculating pump hose, fill hose, or air hose to agitate the water?

Mike
Title: Re: Post-exposure dip tank?
Post by: GKitson on November 06, 2013, 04:45:51 PM
Greg's always coming up with cool ideas!!!

Greg, that hose going into your water tank, is that a recirculating pump hose, fill hose, or air hose to agitate the water?

Mike

Electric cord to a 110V 1200W Stock Tank heater, (think cattle & hogs have to drink in the winter) with a thermostat, warm water works better!

~Kitson
Title: Re: Post-exposure dip tank?
Post by: Gilligan on November 06, 2013, 04:56:51 PM
Greg's always coming up with cool ideas!!!

Greg, that hose going into your water tank, is that a recirculating pump hose, fill hose, or air hose to agitate the water?

Mike

Electric cord to a 110V 1200W Stock Tank heater, (think cattle & hogs have to drink in the winter) with a thermostat, warm water works better!

~Kitson

This was my original thoughts for heating the water.  That's when I started thinking about thermal hot water on the room.  I wouldn't think it would take much of a tank on the roof to really capitalize on the sun for this purpose.

A little clever plumbing should eliminate the siphon effect as well as purge out any air in the line.
Title: Re: Post-exposure dip tank?
Post by: screenprintguy on November 06, 2013, 10:01:55 PM
Greg's always coming up with cool ideas!!!

Greg, that hose going into your water tank, is that a recirculating pump hose, fill hose, or air hose to agitate the water?

Mike

Electric cord to a 110V 1200W Stock Tank heater, (think cattle & hogs have to drink in the winter) with a thermostat, warm water works better!



Thanks for the reply Greg. Ours is warm all the time lol. Good ole central Fl.

~Kitson
Title: Re: Post-exposure dip tank?
Post by: Stinkhorn Press on December 11, 2013, 04:30:45 PM
turn your dip tank horizontal (ok, so it's not a dip tank, it's a plastic tub), keep it 8" of water and you can keep burning screens and feeding them to the bottom of the stack - no time holdup of only holding two or four (also much easier to clean as it WILL get scummy).