A better way to prevent ink clogging with water base

7494 Views 12 Replies 6 Participants Last post by BroJames, Jul 20, 2010

ruxvellprints

Discussion Starter · Jul 17, 2010

* Back flooding - is sometime risky specially when idled for too long ink will tend to clog due to the fact that air passes through on the substrate side of the screen causing it to dry.

* Spraying water - will often cause ink to bleed if overdone unfortunately there is no "undo" command button in tee shirt printing.

* Use the recommended ink - what about the other ink?

Any other better idea? or should we just stay away from water based ink and just stick to this very demmanding curing process for plastisol ink?

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rudi

· #2 · Jul 17, 2010

Mix some "glycerine" in with your ink.

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There is an easy way to prevent ink clogging if you are using line table setups nut can;t apply it on a rotary press.

Heard about adding fertilizers and some other stuff too but never tried them as I have been using medium drying opaque and transparent inks since. Some people use medium drying CMYK bases and add them to a more opaque base for spot color printing. You need to experiment if the inks are compatible with each other though.

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tlbays

· #4 · Jul 17, 2010

Hi all.....

There's an additive for most waterbased inks known as a Retarder.
It is a chemical that slows drying of the ink, and can help greatly in arid print conditions.
An example is called Printgen MG from Matsui-Color.
You use it sparingly (2-6% by weight) since it can also frustrate proper ink curing performance.

Believe it or not, printing with warm pallets (130F) can also aid ink flow and reduce coagulation with the Acrylic formulas that are commonly found.

We have been supplying screenprinters in the arid Southwest U.S. for over 20 years and are all too familiar with tactics necessary for WB printing.
More tricks are employed to deal with our low humidity and dew points below 10 and temps above 110, but not relevant to most readers of this forum.
It's sounds crazy, but we often talk to clients about best management of their waterbase ink jobs with careful attention to their Swamp Coolers.

Happy trails!

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printing40years

· #5 · Jul 18, 2010

Yep, most of those retarders are glycerine based. Yep they slow down the dry time, but you still gotta keep movin' on warm days. Some ink brands have more glycerine already in them than others so shop around.

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BroJames

· #6 · Jul 18, 2010

tlbays said:
...
Believe it or not, printing with warm pallets (130F) can also aid ink flow and reduce coagulation with the Acrylic formulas that are commonly found.
...

Can you please elaborate on the 130F reducing coagulation? Would you have an estimated time, or a calculated range, before inks on screens, above 130F pallets starts to clog? What type of WB inks has acrylic formulas and which does not.

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tlbays

· #7 · Jul 18, 2010

Hello Angel

The 130F is something we confirmed in print techniques at our customers shops.
Note that Matsui, for example, lists this spec on its tech sheets for their 301 Series Waterbased Inks:
[media]http://www.advancedscreenprintsupply.com/TechData%20Matsui%20301%20Series%20Overview.pdf[/media]

You'll find that the evaporation of water on the surface of the waterbased screen actually "cools" the screen/ink during printing.
......the warmed pallets then help enable flow.

Many waterbased ink formulas that don't require a catalyst and need 300F temps for cure to wash-fastness are acrylic formulas that reduce and wash up with water.

Also note that many manufacturer-recommended retarders are a chemical called propylene glycol.

Happy trails!

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BroJames

· #8 · Jul 19, 2010

screen outlaw, it would be highly appreciated if you can give an estimated time frame before inks above a 130F or so platen starts to coagulate.

I have tried some Japanese waterbased inks which are a very very nice ink to print with(and quite opaque). I asked about the brand but was simply told they're japanese inks but there is a strong possibility that they are matsui inks. They are long drying as if they're plastisols and are cure as if they're plastisols. They cost more than regular plastisol process inks. However, I am pretty sure that adding fixers is still recommended

By catalyst are your referring to what is usually called a fixer?

The glycol you mentioned, would it happen to be glycerine derivative?

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ruxvellprints

Discussion Starter · #9 · Jul 19, 2010

"Tulco screen printing supply" describe fixer UR & UX as "A self curing additive that allows the inks to cure within 72 hours without heat curing. Although heat is not required, curing at 150ºC for 15 seconds or more will result in a reduced setting time"
my question is, is it prolonging the curing time or shortening the curing time?

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BroJames

· #10 · Jul 19, 2010

ruxvellprints said:
"Tulco screen printing supply" describe fixer UR & UX as "A self curing additive that allows the inks to cure within 72 hours without heat curing. Although heat is not required, curing at 150ºC for 15 seconds or more will result in a reduced setting time"
my question is, is it prolonging the curing time or shortening the curing time?

I never really paid attention to that bec I heat-cure my prints but based on your quoted description it does seem to prolong the curing time. However the main use of fixers is for color fastness and not for reducing or increasing curing time. If it does indeed increase the curing time then it is just a side effect of the additive.

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tlbays

· #11 · Jul 19, 2010

Be wary of terminology used in our industry.......

In most cases, when referring to water-based ink additives,
-a catalyst is an additive that can complete some degree of cross-linking (curing) of the ink coating, seperate from a traditional energy source.
-a fixer is often best described as an additive that can impart additional characteristics to ink performance.

To my knowledge, Glycol is not a derivative of glycerine.

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Ingridlaughs

· #12 · Jul 19, 2010

One of my books suggests using plastic wrap over the screen if, for instance, you suddenly have to run to the bathroom, or the house is on fire, but I haven't tried it yet. It works well for latex paint if you wrap up your brushes in it overnight and put 'em in the fridge, so I guess it's worth a shot in a pinch.

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BroJames

· #13 · Jul 20, 2010

Ingridlaughs said:
One of my books suggests using plastic wrap over the screen if, for instance, you suddenly have to run to the bathroom, or the house is on fire, but I haven't tried it yet. It works well for latex paint if you wrap up your brushes in it overnight and put 'em in the fridge, so I guess it's worth a shot in a pinch.

If my house is on fire I'd be more worried about overcuring

But I don't think that will help much as the ink will clog from the thinner inks on the underside. I use a line table setup where you literally place the frame on the shirt(on the platen). I've learned that by having extra platens with a piece of cloth on it, I can rest my flooded screen on top of this(sans any off-contact) and it will not dry immediately. I have rest my screens this way for about 10-15 minutes without the ink clogging (which it normally does in a couple of minutes or so). But others say you can leave it this way for lunch and come back to continue printing.

You may also try this on rotaries. Before leaving your press, put a fabric on your platen and pull the flooded frame down. Be sure there is no off contact and the mesh is pressed flat against the cloth on the platen.

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