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screen printing => Ink and Chemicals => Topic started by: ericheartsu on January 22, 2015, 04:12:30 PM
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This year i'm making it a personal goal to learn about inks and pigments.
One of the biggest thing I want to learn about and understand is the science in curing inks, and how the different inks and colors react with heat!
My first question is, what makes discharge ink fade on shirt over time? What can i do to ensure my prints won't fade after the first wash? First hand i've seen discharge prints with Reds or blues fade after a couple of washes, and I'd like to understand why, and if there is anything i can do to combat it!
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Have you looped those shirts to check for fibrillation?
I was always told that ink penetration was a major culprit for looking washed out. But I have also noticed fibrillation helps at least as much.
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I am sure others will chime in, but I will give a perspective from a manufacturer point of view. Note: This may or may not be the case - certainly not implying.
One: Not fully evacuating all the water in the ink film, thus not fully allowing the binders to crosslink. Most H20 companies recommend 330F for two full minutes. Forced hot air with good air flow. If you cannot get this - then you need to add cross linker to allow for post curing.
Two: The BINDER in the base is what BINDS the pigment. Different manufacturers can have different levels of BINDER. Overpigmenting the base can result in washout, as there is just not enough binder present to hold all the pigment. This is why STRONG pigments are preferred - you can use less and stay within the threshold without adding additional binder. Now if you are using pigments and base from the same manufacturer, AND staying within their recommendations, and fully exhausitng all the water during curing, and you are seeing this - then I would consult with them.
To see if indeed this is the case - you can add additional binder to your ink. Use the standard formula as a control, then maybe add 10-20% additional binder.
Lastly, some people arbitrarily add water as a thinner - some reps even advise this. Me - not so much. Again, let's say you add 10% water, you are spreading the available binder over a much greater volume, thus reducing its ability to hold pigment. A better method is to mix BINDER and water 50/50 and use that solution to reduce viscsity if needed.
Just my $0.02! :D
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Rob good points. I like your mixing binder and water to thin out the inks. I have a bunch of binder that I don't use but I may just add that to my water just because it sounds smart.
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bumping this back up, so i can get some more insight!
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If you have the ink penetration and your cure dialed in, I would start looking at testing different binders and using a fixer.
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If you have the ink penetration and your cure dialed in, I would start looking at testing different binders and using a fixer.
That right there. Cure. Too many shops run the dryer too fast for this type of ink. Or run it through twice. Ugh
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If you have the ink penetration and your cure dialed in, I would start looking at testing different binders and using a fixer.
That right there. Cure. Too many shops run the dryer too fast for this type of ink. Or run it through twice. Ugh
I've done two passes many times, Ugh is quite accurate.
But here is a question for you, Brandon (or anyone who knows). When necessary, do you think 2 passes through the tunnel works consistently, with no other downside except extra labor and utilities??
Some of our discharge jobs contain a foiled element. I PURPOSEFULLY undercure those on the first pass through the tunnel, because I have a hard time getting 100.00% foil coverage otherwise. So we print, do a questionably quick cure, foil them, and down the tunnel again.
Stan
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I agree that penetration and cure are the top two things that need to be addressed.
We're lucky in that we not only get good to excellent penetration but have the ability to cure our inks for 1.5-2minutes at 350˚F with more than ample airflow. It helps with troubleshooting immensely to just eliminate these two variables right out of the gates.
Equally important is the fabric. I have seen certain fabric look like total ass after 10+ washings and other look fantastic; same ink/cure/screen/etc.
I think binder/pig ratio is the final frontier for our shop getting optimal wash results from DC and WB inks. Where we have seen poor results and all other variables check out and it comes down to "what's wrong with this ink?" binder and/or any other chemical mechanisms to ensure the pigment affixes to the fibers seem to always pop up as the culprit.
In my opinion, inks should not be shipped without adequate binder and any other additives required for successful encapsulation of fibers by the pigment/base combination. Given the long string of variables that an ink may encounter I think the best wb/dc ink would be maxed out with the highest quality, most aggressive binder to give you the best possible chance of encapsulating the garment fibers for the long haul. Binder seems to be one of the more expensive ingredients in an ink. I can see why manufacturers need to balance the binder level/quality with the price.
However, I do not like when someone sends us an RFU ink, we print it correctly, cure it to perfection and then it does not do well in long term wash testing. Had this happen twice late in the year- one needed a fixative the other we are still waiting for an answer on but it's clear that ink did not contain adequate binder and it's pig just ultimately "let go" of the fabric after enough washing. DC INKS ARE NOT ALL CREATED EQUALLY. You may not always get what you pay for exactly, some are fantastic at a fair price, other lackluster and overpriced, but there is a difference in what is going into some of the cheap stuff v. the more expensive. This will impact different shops differently however. We use some very affordable components for our DC ink and also some spendy ones.
I love the idea of using a distilled water/binder mixture to maintain the balance of the ink Rob, great thought. We don't use water here as a thinner too much, except to activate the ZFS, we put in about as much water as ZFS. We do add water during those extreme dry times but this is just to combat all the evaporation going on on press. We use penetrant, retarder and softener to make the ink flow the way we want. The nomenclature of these additives can be confusion from brand to brand but they each have a special purpose, with the surfacting properties being our most needed it seems.
If you can't tell, this is a subject that is always on my mind. I got us a usb microscope to help really lock in the last of our testing on these inks this year. Considering where we are at as a shop with this, I think it's going to boil down to fabric and then correct/perfected balance of binder : base : pig. I have done a little nerding out on this and, given the space would probably be making our own inks.
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If you have the ink penetration and your cure dialed in, I would start looking at testing different binders and using a fixer.
That right there. Cure. Too many shops run the dryer too fast for this type of ink. Or run it through twice. Ugh
I've done two passes many times, Ugh is quite accurate.
But here is a question for you, Brandon (or anyone who knows). When necessary, do you think 2 passes through the tunnel works consistently, with no other downside except extra labor and utilities??
Some of our discharge jobs contain a foiled element. I PURPOSEFULLY undercure those on the first pass through the tunnel, because I have a hard time getting 100.00% foil coverage otherwise. So we print, do a questionably quick cure, foil them, and down the tunnel again.
Stan
No. You can def get away with it where needed or even required as with your foil jobs but once the water is gone from the image area the DC process will be altered. That's the main variable you'll be fighting. Try misting the prints with distilled water before you run them back through, could make a world of difference. If you are running them again right after exit this is probably ok though.
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What we've learned in the past few years of discharge printing is that just because something, "discharges", doesn't mean that the pigment has been fulling cured or "fixed" to the fabric. Good penetration is a factor, but you can still have awesome penetration and an improper cure. I got into the habit of adding Matsui's Fixer N to every discharge or water based mix that we make. Folks will say that it's overkill but we never have a print fade. One of our customers that was the main customer demanding discharge printing from us from the get go still has original prints that we did from the start and the colors are just as vibrant as the first wash. Just to be clear on product, we prefer, CCI D-Base, I even use this with zero activator as a base for regular water based prints on light or white fabrics. CCI D-White, and the CCI mixing system for pigments. We always use the boost parameter. For US, the CCI works great, is reliable, no screen clogs, no boogering up on screens with wet on wet prints, no flashing needed in multi colored runs, great cost, and proven to us that the prints last. I use 3% activator when discharging, and add Matsui Fixer N 2%, and if it's a decent sized run, 2% of Matsui's Print Gen. We Never add water, but then again, we are pretty humid over here so maybe dryer climates, especially like Jon's need the water. Folks also say that all activators are the same, I beg to differ on that point, using several brands, the Image star, which I believe is CCI's is what we have the best outcome with. To us, this system has almost no sink during the run, even the activator has less stank to it than others, note that if you cover a discharge mix, and open the next day, it will stank, lol, but for what ever reason, during production, the stink is almost non existent, especially with decent ventilation. We liked the usability of Magna, but it stinks so bad, everyone here complained, and honestly it really bothered my sinuses, maybe the pine oil in it caused an allergic reaction with my allergies, but over all, the mix system that magna has is great, and the base is very thin and easy to work with, for me the smell didn't set well.---personal preference---. I've tried Rutland and Sericol, both good, but I end up back with CCI. I find the CCI product to have a better shelf life too. Sometimes we can go a month or two without a discharge order and then like now, 3 months in a row with a higher percentage of discharge orders. Just my 2 cents, if you are having fading issues, first make sure you have a good mesh count, my go to has become 225 S mesh for wb prints. Always make sure you are getting at least 2 closer to 3 minutes in the dryer to really fixx that pigment in the fabric, and worst case scenario, try some Fixer N in your mix, it's never let us down.
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We tried a fixative thinking it would combat the issue of the fiber ends washing out, Rutland's Fiberlock. Turns out that it actually makes the print worse to use fixative if your curing is already complete. I never would have imagined that but Rutland tech explained it as a product only to be used where the cure cannot be done 100% right.
Fixer N must be different? What's your curing setup?
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340 degrees speed setting 1 on the Heatwave dryer lol, that keeps them in the chamber for exactly 2mins 52 seconds. Same setting since we started doing discharge because we were initially instructed by a Matsui Rep that you need a solid 3 mins, CCI Rep confirmed the same info with their product when we switched. I know I can run things through faster and, "see" a discharge, but we always want to be sure that pigment is cured in. I'm not sure of the fixer product you mentioned Zoo, but I know the Fixer N looks like skim milk. I also whip this stuff up with a drill and let sit for several minutes before getting it in the screens. I always have the indication that it looks ready when there are a bunch of little bubbles at the top of the mix. I don't know if any of this has any "actual" function, but, following these steps has never let us down. Different shops have different preferences. I know guys who soley use Sericol, right out of the bucket and love it and "say" they have no issues, but I've had a mutual customer give me shirts as a gift printed at the same shop that prints faded after a few washings. Could be not enough ink dug in there, could be needing fixer, I know their dryer would cure the bubonic plague so it couldn't be bad curing. It just confirmed to me to stick to what we are doing. Another thing brought to my attention two years ago is staying on top of your dryer's air flow. If things are dirty, flow isn't good enough it can have a bad affect on the initial cure. I'm not sure how true that is, but I just try to keep our blowers cleaned monthly to not run into any issues. What works for one shop may not work in another though. Like said before we are a high humidity area so the length of time in the oven makes all the difference to us.
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At your temp, and speed, do you ever see shrinkage in the shirt, or burns? Do you use the same settings for WB ink?
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The Heatwave is a gas dryer with convection air, not sure what to do if you have an electric dryer, I know if there isn't airflow you are kinda skating up a hill. With a gas dryer, I haven't seen a shirt, even poly "burn". Now shrinkage, there are some shirts that it's almost impossible to avoid that, like tri blends, freakin hate them especially when people want water based inks. For that, Green Galaxy makes some awesome inks that you can add their "warp drive" to, and cure them very fast at below 300 degrees. 340 "shouldn't cause a lot of shrinkage" if you temp test and see that your print is hovering at that 330-350 mark, if it rises up then you will probably see some shrinkage. We just ran a big batch of bellas and canvas, it was really humid today so we had the heat up in the dryer to 360, same speed, everything was nice. Dryer day I would have brought the heat down to 340. Really the battle is the time in the dryer. I only have 8 feet of heat in the Heatwave so it's not, "ideal" for w/b printing, you really want 12' for more, but I know that's not always an easy run to the store and buy a bigger dryer, so we just slooooowwwwwwwwwwwwww down, which sucks, but it's better than 500 fashion fit shirts with multi location printing coming back because the ink is washing out. That new Sprint 3000 is built with the WB printer in mind. When we were up at the plant for the tour we were shown how the design lends itself to forcing more of the hot air down and through the shirts to get the ideal cure of waterbased/discharge, and HSA inks, nice machine for sure, but until any of can get into one of those, slowing things down is the cure I guess.
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We found that after producing matching color in the prints that after the first wash they lose some punch. The problem was not the ink, it was back dyeing from the shirt color. Black is epecially prone to releasing excess fabric dye that will color the print. You can pre-wash the shirt, but then other issues of shrinkage, wrinkles and all that labor didn't make any sense. We eventually went to making our own shirts with local cut and sew and dye houses who fixed the dye better, not cheap.
The cure is also key. Gas fired hot air 20' with electric in and out has all the controls you need to dial in any combination of cure for the discharge, puff, or specialty inks. Forced air is much more gentle on the fabric as well. All electrics can burn the shirt. Try pulling a black shirt sideways to see if it splits down the middle, this can happen on inexpensive open end shirts that get more radiant heat than is needed to cure the discharge. Hot forced air and belt speed with a long tunnel helps to keep production up and labor costs down. We had electric in and out. This is hard to come by today, but the advantage is you can get plastisol/gels/puffs/adhesives up to temp quick and then all gas forced air that follows can finish the plastisol/specialty ink cure as it is bringing the discharge up to a steaming temp to do it's work. ( Once you have evaporated the water portion of the ink it may not hit the color on the second pass since it can't steam properly to get the disharge process to work.) For specialty inks the electric out can be handy to finish puffs, gels or hd.
For foiling we put on an oven extension with heat presses next to the belt to apply foil to hot gels or foil adhesives. At this point it only takes <5 seconds to marry the foil. One recipe to try is 110 puff ink/light flash to dry but not puff using quartz flash followed by 60 mesh w foil adhesive (IC). This will work wonders on keylines to give a 3d textured puff foil, (our #1 embellishment for Disney). We foiled as they came out of the oven, with the key feature to run them through the oven a second time to raise the Wilflex puff underneath the foil giving it a gold nugget look (Textured line work or rough line work helps. Avoid solid areas with this technique. A 1-2mm line weight works well with a coarse mezzotint. These jobs often had 6-8 colors of discharge as well. The discharge was the easy part with 20' gas ovens, the shorter oven we had never had consistency to do top shelf production.
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The Heatwave is a gas dryer with convection air, not sure what to do if you have an electric dryer, I know if there isn't airflow you are kinda skating up a hill. With a gas dryer, I haven't seen a shirt, even poly "burn". Now shrinkage, there are some shirts that it's almost impossible to avoid that, like tri blends, freakin hate them especially when people want water based inks. For that, Green Galaxy makes some awesome inks that you can add their "warp drive" to, and cure them very fast at below 300 degrees. 340 "shouldn't cause a lot of shrinkage" if you temp test and see that your print is hovering at that 330-350 mark, if it rises up then you will probably see some shrinkage. We just ran a big batch of bellas and canvas, it was really humid today so we had the heat up in the dryer to 360, same speed, everything was nice. Dryer day I would have brought the heat down to 340. Really the battle is the time in the dryer. I only have 8 feet of heat in the Heatwave so it's not, "ideal" for w/b printing, you really want 12' for more, but I know that's not always an easy run to the store and buy a bigger dryer, so we just slooooowwwwwwwwwwwwww down, which sucks, but it's better than 500 fashion fit shirts with multi location printing coming back because the ink is washing out. That new Sprint 3000 is built with the WB printer in mind. When we were up at the plant for the tour we were shown how the design lends itself to forcing more of the hot air down and through the shirts to get the ideal cure of waterbased/discharge, and HSA inks, nice machine for sure, but until any of can get into one of those, slowing things down is the cure I guess.
yeah the bella/canvas triblends were what i was thinking about, as we've had some issues with those. Right now we are running our sprint international at about 360, but at the slowest speed i can get, i'm still only getting 1min 30. I need to tweak it a little more to allow it to go a bit slower.
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You're absolutely right screenprintguy, it takes a way bigger/badder dryer than you might think to do this efficiently. When we were lining up dryer everyone, myself included thought the Sprint High Output was going to be overkill but I am very, very glad that is what we ended up with. Even at 16' of chamber and all that airflow and btu it still just keeps up with two presses running wb/dc/hsa. I'd second Alan's 20' chamber suggestion, sounds just about right from our experience. If that length won't fit I'd look at 72" belt v 60" then.
I didn't know there was a change in circulation with the Sprint 3000, that's interesting and also good to hear. What did they modify? My guess is the air knives where re-designed?
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Just a quick note to all who replied here: good stuff and thanks! There is some great information here than can be used as a resource.
A couple of quick comments -- These were covered by others; but I think they are important! :)
Yes the discharge process can happen before the ink is "cured" (read: water evacuated).
You also do not want to start the discharge process, stop, and then restart (read: run through dryer multiple times). You can easily get significant color variability.
As far as binder percentage by the manufacturer -- agree 100%. Sometimes there is a reason that a product is much lower costing. Same with the pigments. You are limited if these are on the weak side.
All in all - good advice here in this thread!
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You're absolutely right screenprintguy, it takes a way bigger/badder dryer than you might think to do this efficiently. When we were lining up dryer everyone, myself included thought the Sprint High Output was going to be overkill but I am very, very glad that is what we ended up with. Even at 16' of chamber and all that airflow and btu it still just keeps up with two presses running wb/dc/hsa. I'd second Alan's 20' chamber suggestion, sounds just about right from our experience. If that length won't fit I'd look at 72" belt v 60" then.
I didn't know there was a change in circulation with the Sprint 3000, that's interesting and also good to hear. What did they modify? My guess is the air knives where re-designed?
From what I understood in conversation with Rich Hoffman was that the Sprint 2000's burner was good up to 16' of chamber, and the new 3,000's burner was good up to 20' of chamber and something to do with a higher velocity blower and the air knives, "I think" allow more flow from the 2,000. At the plant Dave Zimmer had said a ton of thought in the 3,000 came from all of the R&D that they had been doing with HSA inks for different big clothing lines, like Nike as well as the ink Manufacturers themselves. I would assume the new design is to allow printers to still have a high output using waterbased inks like they can have with plastisol. I can only imagine a printer needing to run water based prints at 100 dozen an hour or more would need a dryer that gets the job done properly. Also the 3000's has new controls among a ton of other things so instead of setting a speed you program recipes so that an operator can easily re-load a preset for the desired temp and dwell time, pretty cool stuff. I think there are sensors in there that measure substrate temps as well. 244 will probably chime in on more specifics but the one we saw at the plant, even with the big side panel open was quiet, cool and a serious looking machine for sure.
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The dryer is the biggest issue with production, especially if you feed more than one auto printing wb and discharge through the same tunnel. 2 large wb/discharge prints in the same oven requires even slower times as the water evaporation loads up the humidity levels and affects curing. Our Electric in and out with 20' of 2 gas burners for each 10 foot section maxed out with 2 presses. (although we printed night shirts and beach wear with huge prints, smaller prints would be easier to cure). If you load up the 60" wide belt with three presses of printing wb the curing was often marginal, requiring presses to slow down to avoid loading the belt with so many shirts that returning hot air was blocked by all the shirts. This reduced air flow trapped humidity in the oven chamber. Having some space between shirts helps air circulation. A short tunnel or too many wb presses feeding the oven makes it hard to get consistent discharge affect. We often put a quartz flash in the last head to get the process started so the oven did not have do all the work to get the ink/shirt up to temp w/ just hot air. A good flash before the oven also helps spot pinholes much sooner than having the catcher find them. Change filters or wash out permanent filters weekly, or daily depending on 24/7 production. Air circulation is the magic bullet to cure. Oven maintenance of air flow, cleaning out all dust build up including jets, new air filters, watch for pellons blocking air exhausts, check air exhaust for large clumps of shirt fibre. We did this monthly, as all surfaces need to be free of dust build up and especially blocked airways or exhausts.
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Feel free to PM on matching color with discharge. PMS color is always a ball park match, consistent color matching within a design is possible, guaranteed PMS color matching is not due to so many factors.
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Just wanted to commend Mr. Buffington on providing a great example of a manufacturer/rep. sharing valuable information
and experience on our beloved printing process. He has something to sell, but he's not trying to sell it to us. Hell, the subject
at hand has little/nothing to do with the products he manufactures! Other companies take note, this is how you do it!
(doesn't hurt that the products they make are top-notch to boot)