Multiple Day Job on DC/WB?

[ScreenPrinter123]

So, when you guys have a multiple day job for wb/dc (let's say 10,000 shirts you won't get through in one day), do you guys make two sets of screens for each day or do you clean up your screens/squeegees/floodbars and leave the same screens up?  If so, what do you use to clean off the screens? Just water or a screen opener cleaner made for wb/dc?  I ask because we cleaned ours up with just water at the end of the first day, and while the regular open areas did ok, some of the halftones got blocked/plugged with ink -- and the next day when we went to print, we had to wipe so hard and so long on the halftones with water that we rubbed out some of the halftones, stopping production altogether.  So, I'm curious what the experienced peeps do when they have a 2 day or multi day dc/wb job to keep their screens free from getting clogged for the following day when they are stopping at the end of a day.

Thanks

[jsheridan]

if you know you have to stop for the day, clean with water really good the moment you stop printing.

If you need to, there is a waterbase screen opener.

[tonypep]

For halftones 55+ we will usually burn new screens. Don't forget that hardener!

[ScreenPrinter123]

Thanks guys -- I think I'll probably get the screen opener for those situations.

Btw, we got 1,300 wb pieces on aquasol hv, no diazo, using CCI's hardenX (and that was with 4 colors so on 3 of the screens you had wb attacking the bottom side of the screen too).  We also post exposed some and didn't post expose one of them -- the one that we didn't post expose looked like it did when we started -- so at least up to 1,300 prints, there's no benefit to post exposing.  This will be our new emulsion for wb,dc, and plastisol, for it has similar exposure times to chromablue, unlike some of the other dc/wb diazo emulsions on the market that we've tested, and great resistance, at least if regular wb and dc will be similar.

[JBLUE]

On ten thousand pieces we would have burned two sets of screen off the bat. Cheaper to burn them up front and have them sitting there than it is to have to wait to burn them, dry, add hardener, and dry again all the while your press is not turning making money.

Nice to see another person dispelling the myth of post exposure. If you expose it right the first time there is no need to post expose.

[brandon]

On ten thousand pieces we would have burned two sets of screen off the bat. Cheaper to burn them up front and have them sitting there than it is to have to wait to burn them, dry, add hardener, and dry again all the while your press is not turning making money.

Totally as well for us. A lot of the times the reason we loose a screen is not the screen itself but human error. I swear some of our guys are on Cloud 9 Mars half the time. And I am the one super sick right now with medicine head and still have to make sure things are flowing well. But for jobs like this if the screens need to stay up at the end of the day we clean out with just water right away and do not have problems.

[tonypep]

I think some of you are missing the point on post exposure. We are blocking out with emulsion and use very little tape. If you don't post expose that unexposed emulsion can breakdown over time.

[alan802]

I thought post exposure was to "harden" the hardener and what Tony said?  Does the hardener not need to be exposed to UV?

[tonypep]

The hardener needs to air dry with no fans. This is the final step after post exposure (for long runs)

[ebscreen]

Post exposure for us means putting screens out in the sun to dry. I don't know
that I've ever post exposed with artificial light, even during the winter.

As for the original question, we start with water, if it's sticky, move to Simple Green
and then Citra Paste if necessary. Most plastisol cleaners work well on WB.

But if it comes to halftones, I'm with Tony. Too many minute variables there.

[JBLUE]

I thought post exposure was to "harden" the hardener and what Tony said?  Does the hardener not need to be exposed to UV?

The hardener does not need to be exposed to uv. We try to put the hardener on a day before and let it sit. The longer it sits the better it works. Sometimes that does not happen though like today. We just ran 300 pcs with a screen that has been dry for 15 mins. Dried it with a fan then put hardener on it. Let it air dry for a few and back on the press. Not what I would recommend but we needed to do it.

[brandon]

I think some of you are missing the point on post exposure. We are blocking out with emulsion and use very little tape. If you don't post expose that unexposed emulsion can breakdown over time.

Yes, same here and tape on the inside of the screen. Let the emulsion breath

[Colin]

So, I actually talked with Murakami tech the other day about the minute details for using their part A&B hardeners.  They recommend Post Exposure (double the initial exposure time) to finish hardening the emulsion... even if you had a full exposure the first time.  They say there is still 10-20% of the emulsion you can harden on the squeegee side.

We are using the Aquasol HV with Saati Fixer 9 and we typically get 8,000 - 10,000 (sometimes more) squeegee strokes before breakdown.  This is on regular t-shirts.  65/90/65 squeegee.

On Next Level ribbed tanks we had less than half that... we got about 3,000 squeegee strokes before our white screen broke down, several times.  Yes, we were running with heavier pressure due to trying to get good penetration of the ink through the ribbing.  55/90/55 squeegee.

Otherwise, clean screens out good at night and load em up the next morning.  Print away.

[ZooCity]

Watered down Simple Green in a spray bottle is a very handy multi tool to have all over the shop and I use it for WB color changes.  Maybe not needed but speeds up a color change/clean up, you don't have to scrub as much.  I'm a believer in a little soap with the water for wb cleanup it just seems to clean more thoroughly with less.

I always avoid pulling ink or doing a color change with high lpi halftones but your wb screens should be able to handle it. If you are getting delamination from scrubbing try this:  pull, ink, hit with simple green scrub gently on squeegee side, wash out with hose pressure or press wash on fan spray at a distance in the booth. 

Initial exposure is the key.  Our screens are shot and then dunked in a tank of water then blasted out with a pressure washer at 6" away.  If they survived that, well, after post-expo and hardening they can survive a color change.  One of our repeat screen sets lasted an entire season last year, high number of DC prints and constant color changes and not only held up to all that but actually reclaimed easily and I was amazed to find the mesh was breaking down before the stencil!

*I admit that 10k prints, back to back may be a different story.  Haven't done anything like that yet, only up to 1k.

Hardener-  We wipe on Murakami MS and hit the image area, the open mesh, with air let it dry and go to town.  We don't really soak the hardener long at all and often put a fan on it. 

Post expose- Yep emulsion blockout needs it.  And I swear there's some benefit to 2x exposure on the squeegee side but that is not from empirical data if you will.  I guess Colin's post kinda confirms that but I'm sure you can skip with a really through initial exposure.  I would want a very high wattage lamp to skip it on long runs though.

Post exposure for us means putting screens out in the sun to dry.

Used to be for us until some jackhole stole a 330tpi M3.  My coworker has caught other jackholes loading them up into their car.  It's not so much a crime thing, just a dumbass thing.  I don't think most folks even know what they are they just think if it's outside it's free for them to have for some reason.  I use the expo unit now.

[Spreading Ink]

We regularly have jobs that will print all day and then still need to be up for the next morning - we simply clean out screens with water as soon as we stop and use the same screens next day - no real problems.

I agree with those here that say it's really important to get your exposure right on the first pass - we only do post exposure to cure any emulsion used to block out areas along with a hardner.