Ink clogging in silk

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ChurchTheArtist
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Joined: Tue Aug 23, 2016 2:08 pm

Ink clogging in silk

Post by ChurchTheArtist »

Problem:
White ink on black shirt. I can push the ink through for a good two coats on the first shirt but when I get to my second and third shirts, the ink seems to be almost dried in the silk and won't push through.

Details:
I'm using Union Plastisol ink from Tubelite and it's brand new. I have printed a small order of shirts successfully then stored the ink in a cool environment for about two weeks and am trying to do a second print run. I mixed in an extender base/soft hand when I first started because ink was too thick. I'm printing on both 100% cotton and 50/50 blends. I'm using a new squeegee. I have printed on these shirts before with success. I'm using a manual press that has printed successfully. I'm using a 160 screen that is old but barely used (the company I bought it from is questionable).

I've already tried:
I've tried different offsets from a pinky's width to a dime's width; absolutely no difference.
I've tried various pressures; absolutely no difference.
I've tried adding more ink to the screen.
I've tried multiple passes wet on wet but it's only building up in the small spots unclogged.

Conditions:
I do live in central Alabama and it is still summer. My temporary shop is located in a large building the size of an aircraft hanger currently being used for large scale storage. It has 20ft ceilings, it's an all metal building, it's not insulated or air conditioned; I use the bay doors on the two ends to allow a breeze through when it gets too hot. For the past month, we've had consistent three digit temperatures with 85%+ humidity, all day every day. It has been overcast today so I was trying to print during the low 90 degree temperature.

Prior success:
I had been getting up at 3am and printing before the sun came out because the heat was unbearable in that giant oven of a storage building. I had had this problem before where after printing both white and yellow ink it would seem to marble in the silk, thus clotting and blocking the print but after adjusting my offset and printing a few swipes wet on wet with heavy pressure, I was able to get an even coat. After printing numerous successful shirts, I gathered the batches of thinned ink in containers and stored them in my air conditioned house for a couple of weeks. I keep the house around 72-75 degrees.

I am using the same batch of ink but it does seem slightly thicker as it likes to accumulate on the squeegee and not slide off onto the screen. Can this extreme heat/humidity be drying or thickening my ink? Does this mean I am going to have to add extender base almost every time I pull out the ink?

I have been told "use (X) chemical to clean the screens" but that doesn't help me prevent the problem from continuing. I have been told to add the soft hand and I feel like after cleaning the screen and then adding more soft hand it might help... but what is causing this? Is the effect of soft hand only temporary? Does ink naturally get harder and harder in the short course of a few weeks? Will I have to mix in more soft hand with each print attempt? I don't just need to know how to unclog my screens, I need to know what's causing this and how to prevent it so I'm neither cleaning my screens every other shirt nor going through gallons of softhand in months. Is there a better way to keep inks soft during storage?
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Catspit Productions
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Re: Ink clogging in silk

Post by Catspit Productions »

Okay you provided a lot of details here which helps me out but without knowing more I can only guess it is one of two things.

The first thing that could be causing this problem is using a flash cure unit on press while you're printing. So if you're printing the white ink and flashing it and then printing it again, it is likely that you are semi-curing the ink in the screen. If you do a print/flash/print in order to get the opacity you want, then you need to wait for the printed ink to cool down after flashing. If this is the case, then print your base layer and flash it. Then print the second layer AFTER you allow the shirt to cool off.

Also the pallet will get hot as you flash and you may need to stop in order to allow the pallet to cool off too.

The other possible issue is the additives you are using. It is possible that the reducer or the soft hand base will make the plastisol ink tack up and get very thick as it ages and is exposed to the air. Honestly in this case it's really an inferior product issue. Plastisol ink should be very easy to print and it should not clog on screen unless it is heated up quite a bit. But I would also recommend only mixing enough additives into the amount of ink you need at the time. Do not mix the entire quart with the additive. Rather only mix enough for what you're printing at the time.

And of course it's always recommended to use the most open mesh count possible for the artwork you're printing with plastisol ink.

It is possible that excessive heat and humidity can cause problems but I print here in Phoenix where it is often in excess of 100°F. A lot of times we experience 110° F easy but our relative humidity is very low peeking out at about 20% or so. In this case I don't think that it is the heat or humidity that is causing the issue. There a lot of people who are printing the same conditions every day and don't have this issue.

I hope this helps out some. Let me know if you have further questions.
Jonathan Monaco
Catspit Productions, LLC
Learn how to screen print tee shirts!

http://catspitscreenprintsupply.com/
http://www.youtube.com/user/CatspitProductions
ChurchTheArtist
Posts: 2
Joined: Tue Aug 23, 2016 2:08 pm

Re: Ink clogging in silk

Post by ChurchTheArtist »

Yes, it does help. To be honest, after more stubborn attempts I came to a similar conclusion.

The first thing I did was set up my print rotations so that I print a layer, flash left then swing right in the path of a small shop fan while I print the next shirt to the left. I would do this one layer at a time. Due to my ink coming from the distributor very thick (almost solid) I did have to thin it out which means I have to print 2-3 layers for yellow, 1-2 layers for black (on white) and 3-4 layers for white (on black) to get anywhere near the color I wanted. But with the added rotation using the fan I did seem to extend my usage a bit by cooling the shirt between flashes. (It did bring up a new issue where I'm getting that fuzzy texture in my ink if anyone wants to inform me on what I'm doing wrong there, that'd be appreciated.)

I spent the last two nights working out this dry ink problem but still I come back with this...

So the first couple of hours goes by relatively smoothly but slowly I start to find both my yellow and white getting thicker and thicker. I would occasionally have to stop printing to clean the mesh because it just wouldn't push out. The rotation I used (described above) also helped distribute the sequential layer printing over multiple shirts so I wasn't compounding a clot blockage on top of the same shirt. This fix only worked for so long and then the ink started clotting again... slower but definitely not in my imagination. A couple of times I had to completely reclaim the ink on the screen back into the container, remix it with the smooth ink then put it on a freshly cleaned screen. This is what has caused a 2 hour job to grow into a painful all-nighter.

I'll spare you the details of the problems that are a result rather than a cause. I did try to cool the shirt off and it helped for sure but when I saw that the ink itself was indeed going from soft-serve ice cream consistency to something more akin to three week old gum on the bottom of a desk within only (ugh) 7 hours of printing I started to suspect the thinning component. So I refreshed my memory on the brand name and I think I might get some confirmations on this one...

It's acrylic extender base by Speedball. Now, I'm new to all this and there isn't exactly a formal curriculum to learning the more involved details about buying and squeegeeing but from what I've seen over my collecting of supplies, I haven't been pleased with anything I've gotten from Speedball. It's overpriced and over flourished at best but it's the only brand I can find on Amazon for some of the odd chemicals I need that's cheap enough for a start up business. I also noticed that it's like the Hobby Lobby brand (no joke, they stock this stuff) where it's more for the hobbyist instead of a serious user. I fear you may be right and the two gallons I bought may be the very thing keeping me from getting anywhere.

If the ink surface is exposed to air it dries out rapidly. I realized this because the large masses of ink clumps remained smooth but the streaks towards my design got thicker and thicker and the ink that dried the quickest was the thin residue left over in the silk. That tells me it's a surface area issue allowing for the thinnest distributed ink particles to dry within less than a minute after a few hours of printing. I know it wasn't the heat now because I would print a layer perfectly, set up the flash but then have to fuss with it for other reasons causing me to spend over 45 seconds to a minute before I go to print the next shirt. Then I find that the ink dried on the screen just by sitting there (away from the flash) for a minute.

I will look at Amazon's refund policy for the unopened gallon and do my best to make due with all the containers of ink I mixed for my current jobs. If anyone else has any input I would love to hear it. I think I'm slowly learning this stuff so even if people can confirm I'm on the right track it will save me a lot of time, effort, money and trips to the chiropractor.

Also, is there a trick to 50/50 shirt flashing? I noticed when I print the back label (less ink area) I would flash then find that the shirt shrunk on the platen and the first layer is now off registration. I've tried cleaning the shirt press adhesive aerosol can and coating the platens with double dose of stick but still the shirts shrank. I also tried to flash for less time but anything even 2 seconds shorter left my ink wet to the touch. I was doing fine until the last 6-8 shirts when it was like all of them just started shrinking after one flash out of absolutely nowhere. Does it have to do with the shirt needing more broad attention of squeegee pressure to really press it into the tack of the platen or am I just really the most unfortunate idiot screwing up what I've seen pretty much anyone else do with ease?
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Catspit Productions
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Re: Ink clogging in silk

Post by Catspit Productions »

It sounds like you figured it out. Sometimes ink additives can cause the ink to prematurely dry or become thick. So in this instance changing the ink you're using would probably be of great help. A more commercial product will probably perform better.

As far as the fuzzy hairy finish in the screen print, that is called fibrillation. This occurs when you either wash a printed garment and the underlying fibers of the shirt come through the print OR you simply work the ink too much on the shirt raising the shirt fibers into the print surface. They appear fuzzy and tend to make the print look faded. You can minimize this by achieving your print in as few motions as possible. Flood the screen off pallet and get the print off with as few print strokes as possible. Sometimes the shirt itself can be the problem too.

There isn't necessarily a trick to flash curing 50/50 garments. Rather when you flash anything it should only be enough time and/or heat to dry the ink to the touch and no more. Over flashing will cause the garment or ink to shrink. Also make sure to use a flash spray tack made for use with heat.
Jonathan Monaco
Catspit Productions, LLC
Learn how to screen print tee shirts!

http://catspitscreenprintsupply.com/
http://www.youtube.com/user/CatspitProductions
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