Large run waterbase orders

[Dottonedan]

I'm considering doing waterbase but I'm curious to know how they run in production over really long runs. Like do people that specialize in waterbase printing do 10, 20, 30 or50,000 piece orders? The main interest is for the softer hand.

Is there really a concern for drying in the screen these days? If at all, how much down time might there be as compared to Plastisol?I've got the needed main equipment, but I'm wondering if there re any hidden issues to doing large runs.
Any feedback is appreciated.

[mimosatexas]

Last fall we were doing runs of 10k+ on single sets of screens across multiple days. Just 12 houra solid printing for 3 days or so. This was with plastisol. At the end of a run we would have areas where the ink was like chalk around the edges of the print stroke and where things chalked just from the heat of the platens. I haven't run large runs of water based, but I can't imagine there aren't issues with drying...

[brandon]

On large runs use the 2 part hardener that does not reclaim. Better to just cut out when done. Also depending on shop environment (AC, no AC, hot and humid, hot and dry, other variables) you might have to pull ink out say every 500 or 750 shirts and rehydrate. Is it water base, is it discharge, is it HSA, which brand, and so forth. All are different. Including brands. Also be careful of potential color shift due to ink losing moisture such as Metallic water base. But that is pretty rare if you keep your ink hydrated

[3Deep]

This might be bad advice since I've never run in the thousand's with waterbase inks, but what I have done on a small runs of 72 to a 150 is kept a spray bottle with water in it and I would mist the screens just a little, might have custy walk in or take a phone call that takes me away for a minute or two.

[T Shirt Farmer]

On large runs use the 2 part hardener that does not reclaim. Better to just cut out when done. Also depending on shop environment (AC, no AC, hot and humid, hot and dry, other variables) you might have to pull ink out say every 500 or 750 shirts and rehydrate. Is it water base, is it discharge, is it HSA, which brand, and so forth. All are different. Including brands. Also be careful of potential color shift due to ink losing moisture such as Metallic water base. But that is pretty rare if you keep your ink hydrated

Brandon

Does misting the ink with water every 200 or so shirts work or do you feel it better to scoop-add water-return to screen

[ZooCity]

Dan, once your staff is on board with wb basics I would not hesitate to run any number of pieces using any traditional wb/dc ink.  Many of our larger, 10k+ pc runs were done with discharge for example.   Tony P will like that many of those runs were DC, even flo DC, on poly blends.

Hardener is going to be to taste for your screens and shop.  If in doubt, expose, post expo, 2 part (permanent) hardener and always have a backup set of screens to swap out.

With HSA you will need to refresh the ink periodically, my staff likes to just pull it, put in fresh, and rehydrate what was pulled off press.   I don't find this to be necessary with trad wb, dc, medium solids mixes but no HSA with decent opacity is going to be super friendly on press.

Practically speaking, you must double stroke all the heads.  Some presses accommodate fast 2x strokes better than others.   

Watch your taping practices and look at protecting wear points on the screen and emulsion.  At a high production rate, you really don't want a DC ink leak or pin hole to happen.  Nobody can see it on the press where the shirt is pulled and you have 30-50 pcs on belt even if the catcher finds the first one.  And with DC you aren't going to be able to use that spot gun.

I would not run large wb runs without a greaser/lint screen/some kind of lint pickup in head 1.

Just some food for thought. 

[3Deep]

Watch your taping practices and look at protecting wear points on the screen and emulsion.

Even on small runs I would tape underneath the screen were the squeegee edges drag, printing dc/wb you got to over protect for leak and wear spots on the screen.

[ABuffington]

Waterbase printing requires much more careful screen prep, ink management, and other press help not needed with plastisol. 

When Little Mermaid first came out we pretty much printed non stop for a month and a half on one set of screens.  We printed over 250,000 prints.  The key for us was finding an emulsion and technique to make screens that made them bullet proof.  Back then we used Murakami Aquasol TS, an incredible high resolution SBQ.  We built EOM to 15% since it was spot color key line art with the key line an irridescent puff foil.  We used Hardener A and B from Murakami twice.
Coating: 1:2 dull edge, 1 face coat on each side.  (viscosity of Aquasol TS is low at 2500cps)

Drying: In Socal humidity is optimum most of the year, however we still dried this overnight to make sure all moisture was out of the screen.  Dehumidifiers and a room temp of 80 recommended anywhere it rains or has drastic climate changes.

Exposure: 7500w Amergraph (or any 5k-8k MH with a multi spectral bulb) - No LED back then, but I would still advocate Metal Halide for very long print runs.  LED is making great progress, we developed Murakami T9 for use on an LED with post exposure for max LED screen strength.  All SBQ's and pure diazo will expose on the LED, times need to be pushed up to the maximum before over exposure for good stencil strength, post exposure is a must.

Aquasol TS or Murakami T9 Post Exposed in the sun for an hour.  Then we applied A and B Hardeners twice for maximum hardening and dried in the hot sun.  Heat helps hardeners work, so a hot cabinet or hot screen drying room also helps.  Careful, you can over harden depending on local humidity.  This will show up as cracks along the ends of the squeegee path.

Tape out - Here is a tip many have not tried.  It works very well on discharge due to the runny nature of the ink, but also helps to keep any water base localized to minimize surface exposure to air.  You can make ink dams out of the tape you use on the screen. One piece stretched tight across top of frame.  Then another shorter piece adhered about 3/8" over top of tape.  Bend it over and attach 3/8 of tape to the inside of the screen.  this creates one wall, Do this for all 4 sides and plug any holes in the corners with small pieces of tape to prevent ink from leaking in the corners.  The tape walls are placed along the edge of the squeegee path and where the squeegee and flood end.  There are flood bars that keep ink in the center, but some always leaks out and if discharge this ink goes bad sooner and will create dark ribbons in the print since it has lost it's punch.  This usually occurs after 6-8+ hours of printing, but costs a ton in rejects.  This tape out is mainly for discharge and water base.  Newer discharges have great additives to retard dry in and have a longer life during printing, but color shift is controlled with the tape out method and ink management below.  HSA inks are a bit more forgiving and can be handled a lot like plastisol, however these inks are co-solvent inks and very aggressive on the emulsion.  Murakami T9 with diazo prints high res 4/C and sim with ease, often does not need hardening with proper screen prep techniques.

Press Management:
Discharge - Once the activator is added you have a shelf life on the ink.  Some colors lose their punch sooner than others.  We mixed 5 gallon master buckets of color using a gram scale and a recipe.  However, we only activated a quart at a time.  So master color bucket by each head (start a new master bucket when the first has only 1/3 left since a lot of testing is needed to match.)  We would also pre weigh exactly 4% of activator for an exact quart of discharge in small plastic cups  (like the ones for salad dressing at take out with lids.)  Put a lid on it and have trays and trays of these pre made for the ink worker on the press. We had to match color perfectly across tens of thousands of shirts with no color shift.  Discharge inks shift very easily over long runs.  They tend to get darker as time goes by and the ink loses it's punch.  Newer inks do last longer and seem more stable, but we were printing for Disney and it had to be perfect on every shirt.  So we used very careful ink management to insure color was correct and our puller and catcher didn't have to visually color match 10 colors in 1.5 seconds.  Taking the guess work out of printing these inks is key to quality control.

On Press: We maintained ink volume in screen at 3/4 the height of the squeegee, in all screens, all the time to match color perfectly.  This required a worker to monitor ink levels and add a drop dead center in front of the squeegee to keep ink height correct.  This worker also would activate ink at the press.  Fill quart container to the line near the rim, add a pre weighed activator, mix, add to the screen and off to the next head.  We found a good worker could monitor 2-3 presses.

Print issues:  Discharge and water base will build up fiber in the center of the ink over long print runs.  This can create issues that only the catcher will see after the shirt discharges to complete cure while over 20-30 shirts could be in the oven and still on the press.  There will be a darker stripe down the center since the fibers will prevent the right amount of ink from printing.  So every break we would scoop out 3-4 inches in the center of the screens and add fresh ink after break.  At the end of the shift we would throw away all ink left in the screen.  We did run down the level a bit, but for perfect color matching it is better to start over fresh on every shift. 

Cleaning - perhaps the best part of water base is washing up with warm water.  Newer discharge ink can be left flooded for long periods with retarders added, but for our client it made sense to wash screens after 8 hours to clean out fibers, keep the image open, and get rid of any partially dry ink spots that form chips that will plug your screen.  It is crucial to keep ink off of the print carriage since it will dry, drop into the design.  While your cleaning that screen other screens will dry in.  Printing discharge is like a spinning top, you lose one screen to breakdown, fix its, whatever, you can wind up stopping and starting and wishing you had never chosen  screen printing as a profession.  Top quality emulsion, perfect max exposure and screen prep allow you to wash quickly.  Non Stop production is the rule for printing wb, especially discharge.

I work here at Murakami for a reason.  Aquasol TS helped our shop go completely WB with incredible print results.  Murakami T9 with diazo is even stronger and can do most of what Aquasol TS does without hardeners.  Reclaiming is easy and often avoids having to cut out the mesh, which is the only solution with A&B Hardeners.  For long, long runs I would still harden the screens, just cheap insurance.

OVENS:  20' gas fired oven.  We had electric panels on the entry and exits to bump up temps so the gas portion of our dryer could cure discharge and any plastisol prints like the puff and adhesives were fully cured.  When you have 2-3 presses filling the belt, humidity and moisture builds up in the oven and can affect cure.  It is important to have space between the shirts so the oven can circulate the air well to get consistent cure.  One trick for inspection for pinholes is to put a flash in the last head.  Pinholes will discharge quickly and the puller can pick them up.  A black sharpie fixes these easily on a black shirt, but on colored shirts, its a reject that can't be touched up.

If anyone has any questions on the techniques we used I'd be glad to share our tips.  The emulsion and mesh we used were part of our success.  Pretty tough to sleep at night on a 24/7 print schedule if you don't have confidence in your screens!   

Al

[Dottonedan]

Thank you all. Wow. A lot more than I anticipated.  I had seen of much of this in parts sprinkled in various post, but seems daunting when you put it into one thread like this.
Now, I'm not so sure I want to go down this road. LOL.  I'm sure we are going to give it a shot and start out small/slow.

Great info. Thanks to all!

[DannyGruninger]

Dan, I can jump on a call with you if you want...... We are 100% waterbase shop here. We do some big runs(big runs to us are around 10K though) pretty often but a lot of mid size runs 500-1500 pcs. WB vs plastisol is a whole different animal but we're extremely happy with the switch. Lots more work but after 10 months here printing only WB we feel it was the correct decision for our shop.

[ericheartsu]

and if Danny can't help you, i'm also available to chat on the phone. I can tell you all the things we did wrong, and what we did to correct it.

[DannyGruninger]

and if Danny can't help you, i'm also available to chat on the phone. I can tell you all the things we did wrong, and what we did to correct it.

Eric taught me everything I know so I would just have him call you 

[ericheartsu]

and if Danny can't help you, i'm also available to chat on the phone. I can tell you all the things we did wrong, and what we did to correct it.

Eric taught me everything I know so I would just have him call you 

that's true. i did tell danny everything we did wrong, and he just took all of those mistakes and skipped that part.

[brandon]

Hey Dan, it is road I and am sure everyone on here recommends going down. At the end of the day it is not scary or impossible, it is just having patience to document and learn from mistakes. Granted, your first job you might not want to do 15,000 or 5,000 shirts but you would be able to much sooner than you think.

[jsheridan]

Its not water-based ink anymore.. its solvent and all the rules of solvent printing apply.