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screen printing => Waterbase and Discharge => Topic started by: tonypep on February 26, 2013, 07:43:46 AM
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It definitely can be. We've been conducting less than perfect scientific studies across the board on all sorts of jobs; from long runs to short; one color to eight and so on. Lets take a DCUB for instance. Here we're not saving on film, screen, setups. But my comparison of a Rutland SF white plastsiol vs CCI (or anyones) DC white is a 35% ink savings (keep in mind that SF white is cheap @42. per gal). Nothing to sneeze at especially when you get past a $1,000 pc order. Now lets take a 48 pc 2 color order on darks. Here we save on film and screen. Set up time has typically been cut by half as we dont have that pesky underbase to contend with. And not only are we using less expensive ink we are using less of it as we are not laying down a $40 to $60 white plastisol. We have eliminated it all together.
Where can you get hung up? Waste. This its why it's critical to not only to have an organized mixing area but keep well documented formulas at hand. We have found that by underestimating the amount of ink needed for a job and replacing it with fresh ink towards the end (knowing this just takes a few minutes), we will be left with little leftover. Popular colors are mixed in large batches and are activated as needed. This takes seconds.
My best guestimate is that in our shop discharge is between 15% to 20% less expensive depending on the job. We have found that the savings increase incrementally as run lengths decrease.
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There are a few things that are holding me back from going more discharge. The main one being garment curing. I find it to be deceptive when you think it's good, and it washes out. That is a tough one to contend with.
The other is the smell, but that might be taken care of with the new inks coming out.
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It definitely can be. We've been conducting less than perfect scientific studies across the board on all sorts of jobs; from long runs to short; one color to eight and so on. Lets take a DCUB for instance. Here we're not saving on film, screen, setups. But my comparison of a Rutland SF white plastsiol vs CCI (or anyones) DC white is a 35% ink savings (keep in mind that SF white is cheap @42. per gal). Nothing to sneeze at especially when you get past a $1,000 pc order. Now lets take a 48 pc 2 color order on darks. Here we save on film and screen. Set up time has typically been cut by half as we dont have that pesky underbase to contend with. And not only are we using less expensive ink we are using less of it as we are not laying down a $40 to $60 white plastisol. We have eliminated it all together.
Where can you get hung up? Waste. This its why it's critical to not only to have an organized mixing area but keep well documented formulas at hand. We have found that by underestimating the amount of ink needed for a job and replacing it with fresh ink towards the end (knowing this just takes a few minutes), we will be left with little leftover. Popular colors are mixed in large batches and are activated as needed. This takes seconds.
My best guestimate is that in our shop discharge is between 15% to 20% less expensive depending on the job. We have found that the savings increase incrementally as run lengths decrease.
you mean the other way around, right? the bigger the order the bigger the savings?
pierre
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No Pierre. See the screen/film/setup cost elimintaion are less important (expensive) on say a 5K run vs 50 pcs. Does that make sense?
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Yes Brad the fumes are in issue for many (samples arriving today) good ventillation is of course the answer. As far as cure goes that comment raised an eyebrow. We have never experienced this and wash test on site daily.
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I had a job that discharged perfectly, then after the first wash, the print disappeared. I think I had 2 problems...1. I didn't drive the ink deep enough, 2. I didn't cure it long enough.
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We always slow the dryers down a titch for discharge just in case.
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I had a job that discharged perfectly, then after the first wash, the print disappeared. I think I had 2 problems...1. I didn't drive the ink deep enough, 2. I didn't cure it long enough.
Many times the print will fully discharge without being fully "cured", thus the product will not be washfast. As you know, air flow, time, and temperature are imperative.
I did some quick research on-line some time ago looking at various manufacturers curing requirements. For what it is worth, here are the recommendations. Bottom line, significantly more time than plastisol for sure! ps - pulled these a number of months ago, so if some of the numbers have changed -- don't yell!
Temperature Time in minutes
CCI (ideal) 340-350 2-3
CCI 320 1.5
Magna AB-AW 330 3
Magna ULF 330-340 3
Jantex 330-350 3-5
Rutland WB-99 320 1.5
Sericol Texcharge 320-360 2-3
Matsui 300-320 2.5-3
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AHA! My dryers are set to 390 and have 20 ft of heat so 1.5 min works fine all day. Thanks Rob for that info. As we all know retention time is directly affected by dryer efficiency and chamber length.
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I see our point Tony and agree small jobs less time and screens more profit, big jobs tend to pay for themselves and you can hide the cost a little. Example running two whites for a small job vs running two whites on a big job which would you save more on.
Darryl
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It's exponential. Thats why when quoting orders of say 5K or more screen/film/setup costs are often waived as they become meaningless and tend to piss off large buyers.
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I am thinking this woudl depend on a definition of the small job. for us that's 12-24 pieces. I can see the time to mix the inks (add teh agent) and then the cost of having to throw some ink away eat into the profits. BUT I do agree that less screens and no underbase issues makes things easier and thus faster. Could that translate into cheaper too? not so sure . . .
pierre
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Absolutely that would be true we would'nt go there except for the fact we have so many premixed formula stock colors on the shelf (about 80) Which goes back to the original post that it can be.
If I were starting out no; I would probably have a minimum of144 for DC
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Right now color tees are killing me cuz every job needs an under base, which I need to hit twice on our press two rounds which is costing me time, a 200 pc job can turn into a 800 print run if I have to do back and front with UB, so I looking at discharge but I,m just not getting what I want ( white just ain't happen) plus our dryer is to small. I think I,m getting off track now just my rant for the day.
Darryl
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Right now color tees are killing me cuz every job needs an under base, which I need to hit twice on our press two rounds which is costing me time, a 200 pc job can turn into a 800 print run if I have to do back and front with UB, so I looking at discharge but I,m just not getting what I want ( white just ain't happen) plus our dryer is to small. I think I,m getting off track now just my rant for the day.
Darryl
So for example, on a red ink print on black shirt you are doing double stroke, flash, double stroke, flash, then top color red?
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Normally that would be one stroke down the dryer for most discharge printers(double for high mesh). We keep about six unactivated reds on hand and usually one of them will be the right color for the job.
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3 minutes in the dryer is forever. How about 2 runs through the dryers? Our is Gas and Infra-red...
Steve
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Steve - If I can offer some guidance.....
Manufacturers must publish guidelines that they KNOW will work. I spent 25 years at Wilflex, and I assure you that although every cure recommendation for a normal plastisol is 320f ... Many times it is lower. The 320 gives a safety barrier if you will. Also pigments and loadings are a factor in cure temp for plastisol so you need to state a temp to encompass all colors in a range.
But enough about plastisol! Temperature, time, air flow, all play a role in curing discharge. I would suggest you experiment with some consistent printing methods, controlled dryer settings, cure the discharge, document with a sharpie, and wash test several times. For instance if the recommendation was 320 for 3 minutes -- maybe try 4-5 variations - say 330 for 1.5; 340 for 1; 320 for 3, etc. This methodology can help to give you a base line.
But remember, if you do this on a day where the humidity level is 25 in your shop; wnd then run a job after the rain in the summer with the dock doors open and rh at 80% -- well those cotton shirts absorb a lot of moisture and your curing specifications can change. You must drive out all the water from the ink film.
I would be interested to hear Tony and others thoughts on this.
Thanks and good luck!
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Steve - If I can offer some guidance.....
Manufacturers must publish guidelines that they KNOW will work. I spent 25 years at Wilflex, and I assure you that although every cure recommendation for a normal plastisol is 320f ... Many times it is lower. The 320 gives a safety barrier if you will. Also pigments and loadings are a factor in cure temp for plastisol so you need to state a temp to encompass all colors in a range.
But enough about plastisol! Temperature, time, air flow, all play a role in curing discharge. I would suggest you experiment with some consistent printing methods, controlled dryer settings, cure the discharge, document with a sharpie, and wash test several times. For instance if the recommendation was 320 for 3 minutes -- maybe try 4-5 variations - say 330 for 1.5; 340 for 1; 320 for 3, etc. This methodology can help to give you a base line.
But remember, if you do this on a day where the humidity level is 25 in your shop; wnd then run a job after the rain in the summer with the dock doors open and rh at 80% -- well those cotton shirts absorb a lot of moisture and your curing specifications can change. You must drive out all the water from the ink film.
I would be interested to hear Tony and others thoughts on this.
Thanks and good luck!
How about 400 for 45 seconds?........ ;D
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Or a microwave oven for 12 seconds! :o
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Sprint 2000, 12ft. heat, 375 degrees, speed at 13. Take it to the bank! It works!
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Sprint 2000, 12ft. heat, 375 degrees, speed at 13. Take it to the bank! It works!
fastest I've been willing to go is speed 11 with discharge / waterbase
not doubting that works though, used 355 speed 11 for a large non discharge job same dryer
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Good comments Rob. Remember the mfctrs recommendations on heat and retention times are usually based on 12' of heat chamber. Well, that doesn't apply to everyone. Some have 4, others 6 and some 20. . "Retention Time" is exponentionally shorter the longer the heat chamber is so this will differ widely. Also often overlooked is efficiency. Many, if not most dryers have gates located at the enter and exit positions. Lowering them to the sweeet spot helps to keep the heat in and speeds things up.
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The other thing to keep in mind is how much ink you actually are laying down. We run our all over discharge prints through an 86 inch wide interchange with 12' of heat (soon to be 25 foot of heat). Some of these prints can have a lot of ink on them and large areas - the air flow of the interchange is a big help, but we do some jobs that run at 380-400 at 8 ft / min. Others run fine at 12 - 13. I can't wait to get the extension modules to be able to crank that belt speed up. We aren't really doing this to increase our all over production as we currently use both sides of the 86 belt for them, but rather to support another press on this dryer.