Plastisol - Ideal temperature

[Maxie]

What is the ideal temperature for Plastisol?
I've read that in cold climates you can heat inks before printing but is there a recommended temperature one should get to before putting Plastisol on the carousel?

[Prince Art]

I'd like to know too, and would like to know if there's an MAX temperature, too. In the summer, we've lost opacity due to some ink getting almost too easy to print.

Related: Does anyone know the preferred temperature range for storing plastisol? Are there guidelines for what keeps your ink ready to use, and what's cold/hot enough to hurt ink?

[Colin]

Inks, when manufactured, are tested in the lab in the low 70's.  This is the temp they use to make sure the ink is "In Spec".

Typical production temp will be high 80's to low 90's on an auto press.  High 70's to low 80's on a manual press.  Temps can certainly get hotter depending on the flashes used etc.... But at that point you have bigger problems to solve first.

This temp range of course goes out the window depending on your shops physical temp.  I.e 90 degree plus weather will make the running temp of your ink a bit higher.

As ink gets hotter its tendency to print thinner increases.  This is because the the ink is of course hotter and more pliable/thinner.  This is when your screen stencil thickness, squeegee selection/sharpness, mesh selection, etc starts to show its strengths or weaknesses.  Better quality/preparedness = better prints at extreme temps.  Fans help some.

As for storage. 

Plastisol is freeze/thaw stable.  Meaning it can be frozen, thaw out, and be chemically stable.  i.m.o..... its now thicker than you want, but totally usable.  Still cures at its normal cure temp.

As temps climb in your shop, the only inks you NEED to pay attention to are those that are "Fast Flashing"  and potentially low cure.  For low cure inks I don't know what temp they actually start to "cross link"/gell at.  But that is the temp you want to stay away from.  For the fast flashing inks, elevated temps for extended periods of time will cause the ink to slowly gell/flash.  This makes the ink thick, sticky, and generally unprintable. For those who live in hot climates - Texas, Arizona, etc... you will be familiar with this.  Distributors will typically pay to have their ink shipments come by refrigerated truck so it does not turn into a brick during shipment.

If I am adding ink to my screen during the run, I want it to be in the high 70's low 80's so that its print parameters/flow characteristics are as close to whats already in the screen as possible.  The reality is that the inks will not be close and you just slow the squeegee a little for a few prints.

Hope this helps.

[Maxie]

Thanks, our average temp in summer is 79 winter it's 55 so looks like we should heat the plastisols in winter.      At the moment we don't heat, just stir.
Our screen drying room is about 72, we could leave inks in there overnight.

[mk162]

I have to say I think the new series inks tend to get jacked up at a lower high temp.  A lot of our inks turned to concrete after the summer.  Top Score and anything else that is a lower cure temp ink.

We keep the shop round 65 in the winter.  Inks are still a touch cold, but a quick stir and they are good to go.

[Prince Art]

@ Colin - thanks for the great info.

I have to say I think the new series inks tend to get jacked up at a lower high temp.

I agree. We've got older stock Rutland that has been pretty consistent, and have noticed recent OSI inks that have thickened over the course of just 6-8 mos. We just finished an old batch & opened a new one mid-run, and the difference was obvious. Both were printable, but the new was a lot creamier, easier to push. (And this wasn't ELT or Fast Flash.)

It's funny- we're in central FL, and have been looking at air conditioning the shop just to make things easier on ourselves in the summer. But after a prior thread here that touched on ink temp, I started looking at a/c as a way to maintain a more consistent print environment. This thread only reinforces that idea.

For those of you in colder environments- has anyone considered the idea of [lightly] heated ink cabinets? With many shops having dry boxes for their screens, would something similar for ink be worth the money & effort to keep ink at ready-to-use temp? Just musing out loud here. Not sure if this has merit, or if just carting the next day's ink into the screen room (per Maxie's comment) would be easier.

[Admiral]

We are in Michigan and we don't have heated ink cabinets but the white ink has a heat lamp under it on the cart it is on and goes on and off on a schedule which then keeps it about 20 degrees above ambient.

One interesting think we have found out about the temperature of the shop - in the summer when it is very hot our misprint rate is actually at it's lowest, even though sometimes mistakes have been made seemingly due to it being tougher to think due to the heat (on the hottest days of the summer).

[heray11]

 I have heard that its not the ttemp of the white ink, but whhat is called Thixagraphic. In our terms, getting the moluclles hwated first.
 By shiriing up the white iink.  Get an old hobart cake mixer, or any kind, Put the ink in a mixing bowl, before you start your day, and let it stir up the ink, tto get it more plyable. Let the mixer do the stiring for you.
  Its worth a shot, espically with white ink. Also, a little reducer dosent hurt any.
 Some people use a 230 mesh with 48 dia thread. This allows a tiny bit moore in to be applied.
  also coating the screens properly helps.  One inside, flip to one outside, then a final ccoat on the well side(inside)
   I hope this helps somewhat
  Howard RAY 713 344 8604