TSB
screen printing => Ink and Chemicals => Topic started by: blue moon on April 25, 2014, 08:34:52 AM
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so the equipment is here, we are getting used to it. No actual testing has begun as the calibration piece is not here yet. . .
I'd like to start moving through some of the details of printability as I see them. As much other stuff posted here, these are just opinions until proven otherwise!!!
So let's start with the TEMPERATURE. What is happening with the ink as it warms up? What is happening at different temperatures?
pierre
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Do you suspect there would be a perfect temp, or a range of say 5° to 10° on either side of a perfect temp?
Steve
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Do you suspect there would be a perfect temp, or a range of say 5° to 10° on either side of a perfect temp?
Steve
I am pretty sure that the properties change with temperature and that there is a point at which it is performing best (for your press settings). There should also be a window within it acts pretty close to the "best" temp, but how many degrees is the window is beyond me at this point. It is one of the things we will be testing for!
So, going back to the temps, what happens as we go above or below the BEST temp?
pierre
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From what I recall, all ink is 'tested' in the lab at 70 degrees
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From what I recall, all ink is 'tested' in the lab at 70 degrees
is your ink 70 degrees when you print with it?
pierre
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From what I recall, all ink is 'tested' in the lab at 70 degrees
is your ink 70 degrees when you print with it?
pierre
I live in CA.. it's 72 and sunny 8 months out of the year.
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From what I recall, all ink is 'tested' in the lab at 70 degrees
is your ink 70 degrees when you print with it?
pierre
I live in CA.. it's 72 and sunny 8 months out of the year.
so the ink is at 72 when you pick up the bucket, right? and how long does it stay at 72?
pierre
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My white ink was 88 degrees yesterday when I was test printing a design through a 180/48. I was printing at 30"/sec with 35 psi. I will be doing more testing today and I'll do it earlier with cooler ink and I'll let you guys know what type of results I get. I have about a dozen prints that I've been examining and I can't believe the difference between the prints with 4"/sec and 30"/sec, it's worth it to print fast. The 15"/sec prints looked good too, but not quite as smooth as the 30'.
I know most people know this but for those guys who haven't heard it mentioned, print white as fast as you can possibly do it. That goes for every plastisol color as well really, but obviously white is the most important one to focus on in most shops.
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My white ink was 88 degrees yesterday when I was test printing a design through a 180/48. I was printing at 30"/sec with 35 psi. I will be doing more testing today and I'll do it earlier with cooler ink and I'll let you guys know what type of results I get. I have about a dozen prints that I've been examining and I can't believe the difference between the prints with 4"/sec and 30"/sec, it's worth it to print fast. The 15"/sec prints looked good too, but not quite as smooth as the 30'.
I know most people know this but for those guys who haven't heard it mentioned, print white as fast as you can possibly do it. That goes for every plastisol color as well really, but obviously white is the most important one to focus on in most shops.
what do you expect to see with cooler ink?
pierre
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I will throw in my $0.02 here.
Plastisol viscosity will certainly vary with temperature. White inks even more so with all the eye of newt and bat wing additives. An increased viscosity due to cold -s a "false" body. That is, adding shear (temperature) will bring it back. Increased viscosity due to higher heat is irreversible -- the pvc resin has begun to swell and absorb the plasticizer.
Generally speaking, the thinnest the ink will be is around 100-110F. Ymmv. Take a look at this rather crude viscosity chart. Please do not take the numbers as absolutes - they are not. Merely presented to give a visual image as to what happens when plastiso lis exposed to heat. The high end 350+ is a remelt.
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Why are you guys still messing around with plastisol ;)
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As the ink warms up, the body becomes thinner allowing you to print on top of the fabric as you need less pressure to clear the mesh
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Shearing the ink in a turnabout for 10 minutes prior to printing allowed us to use the speed and pressure settings from the night before. I don't know how a lot of shops in colder climates handle the ink, but we used a combination of heating pads at night underneath the 5 gallon white so it stayed warm overnight and then pulled all ink from the screen in the morning to shear it in the turnabout and this was in Socal with temps at night in the 50's.
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Why are you guys still messing around with plastisol ;)
Nice! ;D
I know you are talking about hand-feel, cost, fashion, etc. However, it is only a matter of time, though, for many. 8 of the top 10 global fashion retailers have some sort of PVC restriction in their RSL.
End hijack .... back to your regularly scheduled programming!
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I will throw in my $0.02 here.
Plastisol viscosity will certainly vary with temperature. White inks even more so with all the eye of newt and bat wing additives. An increased viscosity due to cold -s a "false" body. That is, adding shear (temperature) will bring it back. Increased viscosity due to higher heat is irreversible -- the pvc resin has begun to swell and absorb the plasticizer.
Generally speaking, the thinnest the ink will be is around 100-110F. Ymmv. Take a look at this rather crude viscosity chart. Please do not take the numbers as absolutes - they are not. Merely presented to give a visual image as to what happens when plastiso lis exposed to heat. The high end 350+ is a remelt.
fantastic graph, I was debating posting one, but did not have and was to lazy to draw it! Thanx Rob!!!
What can we conclude from it? As Rob already said, it will be the thinnest around 100 degrees. Is that what we should be going for? Is the thinnest the best? Why not set up the press for 140 where the ink has more body?
Alan, what temp was the pad set for?
pierre
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As the ink warms up, the body becomes thinner allowing you to print on top of the fabric as you need less pressure to clear the mesh
so the thinner the better? Is there such a thing as too thin?
pierre
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The downsides of a too thin ink would be opacity and fiber matte down.
Easy to print though.
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The downsides of a too thin ink would be opacity and fiber matte down.
Easy to print though.
What about the perceived stability? The curve at the bottom is a lot flatter then it is on the side. A slight change in temp at 140 would also cause quite a bit of difference in the viscosity! So thin and stable is good, right?
who here is preheating their inks???
pierre
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so the ink is at 72 when you pick up the bucket, right? and how long does it stay at 72?
pierre
In 27 years.. i have never put a thermometer in a bucket of ink and I have no desire to do so.
what I know.. cold and hot ink print like s.h.i.t.. warm ink prints like the beez kneez.
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Not me! In all honesty, with all the great white plastisols out there and with proper press and pre-press paramenters this process is not hard at al. Its pretty easy. We just don't do it often because its rarely necessary at this point.
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I love what you are attempting to accomplish Pierre!
Everyone needs to remember though...... ink prices are vastly different...... ink quality is vastly different.... Typically reflected in pricing.
For everyone who wants to chime in about the right ink, right speed, right production heat parameters.... Please remember what "quality" of white ink you are working with. Also whether the ink is made for cotton/low bleed (cheap)/low bleed (expensive).
Proper production parameters for cheap cotton ink, will not be the same for expensive low bleed ink....
Please post the name/type of ink you are talking about and what your typical production atmosphere is, run size, fabric type, etc...
Case in point: The Comet White from Ryonet. I thought the viscosity was way to low for what we do. It would not matte fibers well. But I was testing on 100% 6.1 oz cotton. Those who loved it did their testing on tri blends and ring spun cotton. Different fabric gave different results with the same ink.
Also, what mesh/mesh opening are you testing/printing your whites through? Screen tension? Off contact? Squeegee blade type/sharpness? Hard fill or soft touch with the flood bar?
Let's make sure we talk about allll our parameters when we pitch in.
This is my 2 cents coming from an ink manufacturing background and a production background.
Keep the convo going!
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I love what you are attempting to accomplish Pierre!
Everyone needs to remember though...... ink prices are vastly different...... ink quality is vastly different.... Typically reflected in pricing.
For everyone who wants to chime in about the right ink, right speed, right production heat parameters.... Please remember what "quality" of white ink you are working with. Also whether the ink is made for cotton/low bleed (cheap)/low bleed (expensive).
Proper production parameters for cheap cotton ink, will not be the same for expensive low bleed ink....
Please post the name/type of ink you are talking about and what your typical production atmosphere is, run size, fabric type, etc...
Case in point: The Comet White from Ryonet. I thought the viscosity was way to low for what we do. It would not matte fibers well. But I was testing on 100% 6.1 oz cotton. Those who loved it did their testing on tri blends and ring spun cotton. Different fabric gave different results with the same ink.
Also, what mesh/mesh opening are you testing/printing your whites through? Screen tension? Off contact? Squeegee blade type/sharpness? Hard fill or soft touch with the flood bar?
Let's make sure we talk about allll our parameters when we pitch in.
This is my 2 cents coming from an ink manufacturing background and a production background.
Keep the convo going!
great points!
so we can control the viscosity of the ink by controlling the temperature. Could we use the same ink at different temps to adjust for the substrate requirements? Why? Or, Why not?
The ink temp is directly related to the platen temperatures. Other than the guys with a IIID, anybody else measure the platen temps? Regularly?
pierre
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so we can control the viscosity of the ink by controlling the temperature. Could we use the same ink at different temps to adjust for the substrate requirements? Why? Or, Why not?
The ink temp is directly related to the platen temperatures. Other than the guys with a IIID, anybody else measure the platen temps? Regularly?
pierre
We have the new flashes from MSI that have the eye that reads the surface temp of the shirts/platens so yes I can control my heat.
We also have honeycomb platens, that cool off very quickly and do not hold heat like the blue boards do. In fact the blue boards are known to get so hot you can't even touch them which in turn heats the inks in the screen well into the 100+ range and even so hot that inks in the screen get tacky and start to gel.
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so we can control the viscosity of the ink by controlling the temperature. Could we use the same ink at different temps to adjust for the substrate requirements? Why? Or, Why not?
The ink temp is directly related to the platen temperatures. Other than the guys with a IIID, anybody else measure the platen temps? Regularly?
pierre
We have the new flashes from MSI that have the eye that reads the surface temp of the shirts/platens so yes I can control my heat.
We also have honeycomb platens, that cool off very quickly and do not hold heat like the blue boards do. In fact the blue boards are known to get so hot you can't even touch them which in turn heats the inks in the screen well into the 90-100+ range.
our platens (also honeycomb) are running at 120 degrees at the offloading station which drives the ink in the first and last head to about 100 degrees. I think that's actually a pretty good place to be based on what we've seen so far. . .
pierre
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We set the heating pad to halfway, never took a temp on it. Grainger sells metal heaters that can wrap around the 5 gallon pail. We had one and placed near the top of the 5
Gallon pail worked better thanjust heating the bottom of a full 5 gallon pail. It was impossible with the heating pad to ever fuse the ink, they just don't get that warm. On really cold days we stored it in the screen room which was temp controlled to 80 overnight. Of all the methods though the band with the 5 placed in a turnabout turned on for 10 minutes at a slow speed worked the best to get consistent viscosity and match print and pressure speeds from the day before.
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For what it's worth, we printed a 500 piece run today and 2 locations so the white ink had 1000 strokes on it at the end and it reached 121 degrees. I was printing at 30"/sec with a Dr J blade. Opacity didn't really suffer that was noticeable by eye. Viscosity changes were obvious but I did compare the first and last print. It got up to 98 in the shop today while doing the print run. We have another 750 piece job to run on monday so I'll observe temps on that run as well. I may slow down to 15"/sec as long as it doesn't affect opacity and other variables or quality and see what type of ending temps I get. I don't know if anyone can do anything with these numbers but I'm observing just because I want to and this is a nerdy subject that I get into. Pallet temps got up to 150 on the backs but stayed at 135 on the front run. Had a slightly longer flash for the larger back print. That's all I got.