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screen printing => Equipment => Topic started by: Prosperi-Tees on November 15, 2013, 11:41:48 PM
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Im having issues getting a good flood. I get a good flood with colors but my whites do not flood well. Am I putting to much in the screen? I think it doesnt drop off the squeegee so that the floodbar can do its thing. I still get a good print but it won't flood like the colors where it rolls forward. Im using Rutland Street Fighter. Any suggestions?
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The viscosity and rheology is different with the
base whites, not as viscous (runny).
Slow flood down some. But if ok w/ 2 hits- ok.
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I have slowed it way down and it only improves slightly. I just think it's the ink just not flopping off the squeegee at the end of the stroke.
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We always had that issue with rutland SF cotton white. Awesome price but I ended up changing to Union premium cotton because it was creamy and flooded better.
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Sounds like you don't have enough ink in the screen. If you're still having issues after that you can add a Very Small amount of curable reducer to it. Some buckets of white are just a little thick but that's a great ink.
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The last time we used SF Cotton White you could load the screen up and the ink would just stick between the flood and squeegee. I'm not much for adding additives. I feel like it's hard enough keeping the press turning.
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The last time we used SF Cotton White you could load the screen up and the ink would just stick between the flood and squeegee. I'm not much for adding additives. I feel like it's hard enough keeping the press turning.
Yup that's exactly what's happening.
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I do think the consistency varies quite a bit in Rutland whites. We been running through 2 5's a week of Snap and last week we had a bucket from hell. Stuff wouldn't flood and I'd have to double stroke the first white on a 110. Slowed us way down.
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Sounds like the ink is very short bodied if it's sticking and climbing the squeegee. Rather than add curable reducer (I think that stuff should not be used very often) I'd add halftone/process base or if you have a longer bodied white on the shelf, like a poly white of some sort. Add that to the short bodied white and you'll get much better results than adding reducer. The white ink manufacturers have all started making the white inks so short bodied and then the longer bodied inks have their own issues.
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If you're doing a hard flood to fill the screen then you need the ink to release from the squeegee so the floodbar can do it's job. If you're just using a flood stroke to get the ink to the front of the screen, then you're just as good having a bead of ink stuck to the squeegee. if it's printing okay, don't worry about it, just make sure you don't run out.
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Sounds like the ink is very short bodied if it's sticking and climbing the squeegee. Rather than add curable reducer (I think that stuff should not be used very often) I'd add halftone/process base or if you have a longer bodied white on the shelf, like a poly white of some sort. Add that to the short bodied white and you'll get much better results than adding reducer. The white ink manufacturers have all started making the white inks so short bodied and then the longer bodied inks have their own issues.
Please elaborate. A teaspoon of curable reducer will change the flow characteristics of the ink considerably without changing opacity. It would take much more halftone base to achieve the same results in my opinion with much reduced opacity.
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I'm on the same page with Alan on that one. It seems as if making the ink less 'sticky' with white can be more important than reducing the viscosity, if that makes sense. Seems like an equivalent small amount of HT base as you'd use reducer makes most inks print more easily.
I'd definitely try it out if you haven't, a quart of base is pretty cheap.
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Sounds like the ink is very short bodied if it's sticking and climbing the squeegee. Rather than add curable reducer (I think that stuff should not be used very often) I'd add halftone/process base or if you have a longer bodied white on the shelf, like a poly white of some sort. Add that to the short bodied white and you'll get much better results than adding reducer. The white ink manufacturers have all started making the white inks so short bodied and then the longer bodied inks have their own issues.
Please elaborate. A teaspoon of curable reducer will change the flow characteristics of the ink considerably without changing opacity. It would take much more halftone base to achieve the same results in my opinion with much reduced opacity.
I'd argue that adding anything with that much plasticizer in it is bad since the ink is likely close to it's max already. I haven't had any issues with having to add so much halftone base to any ink to reduce it's opacity nor have I tested both additives side by side. There are so many things I like to know for myself and learn everything about, but when it comes to the use of curable reducer I listen to those who tell me it's bad and to use halftone base and that's honestly the reason why we don't use curable reducer. When time permits I'll learn more about the chemistry in our inks but for now, I trust the advice from a few others so I can't elaborate like I could on other subjects. This is just a matter of "trust in JC" for me.
I think the real problem with white inks not working properly for us is a lack of stirring the ink properly before using it. In a perfect world, I'd have my white ink in an ink mixer turning slowly all day long. I don't think many shops stir their ink enough and doing it before every single print run would ensure the ink will perform at it's best. I bet most ink is stirred for about 5-10 seconds, once a day at most when it really should be done for several minutes every hour or so throughout the day. I'd bet that if you worked your ink over thoroughly before you use it that it would perform better than adding curable reducer. I personally think the main reason the ink works better after adding curable reducer is the actual act of stirring the reducer into the ink works the ink into it's optimum performance level.
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Sounds like the ink is very short bodied if it's sticking and climbing the squeegee. Rather than add curable reducer (I think that stuff should not be used very often) I'd add halftone/process base or if you have a longer bodied white on the shelf, like a poly white of some sort. Add that to the short bodied white and you'll get much better results than adding reducer. The white ink manufacturers have all started making the white inks so short bodied and then the longer bodied inks have their own issues.
Please elaborate. A teaspoon of curable reducer will change the flow characteristics of the ink considerably without changing opacity. It would take much more halftone base to achieve the same results in my opinion with much reduced opacity.
I'd argue that adding anything with that much plasticizer in it is bad since the ink is likely close to it's max already. I haven't had any issues with having to add so much halftone base to any ink to reduce it's opacity nor have I tested both additives side by side. There are so many things I like to know for myself and learn everything about, but when it comes to the use of curable reducer I listen to those who tell me it's bad and to use halftone base and that's honestly the reason why we don't use curable reducer. When time permits I'll learn more about the chemistry in our inks but for now, I trust the advice from a few others so I can't elaborate like I could on other subjects. This is just a matter of "trust in JC" for me.
I think the real problem with white inks not working properly for us is a lack of stirring the ink properly before using it. In a perfect world, I'd have my white ink in an ink mixer turning slowly all day long. I don't think many shops stir their ink enough and doing it before every single print run would ensure the ink will perform at it's best. I bet most ink is stirred for about 5-10 seconds, once a day at most when it really should be done for several minutes every hour or so throughout the day. I'd bet that if you worked your ink over thoroughly before you use it that it would perform better than adding curable reducer. I personally think the main reason the ink works better after adding curable reducer is the actual act of stirring the reducer into the ink works the ink into it's optimum performance level.
I don't know much about the chemistry of inks but I have asked my ink guy (the manufacturer rep, not a reseller rep) in the past "what's the difference in reducer (which is the same as chino base) primer clear and halftone base (some call it shape"). His response was the viscosity of each. Now I'm sure there is more to it than that but I can attest they all cure properly. I also know all the major ink manufacturers recommend curable reducer as the modifier of choice for their whites (excluding mixing whites). With all that said I would not recommend using reducer for a wet on wet ink. Only for the base screen and maybe highlight if printing last. I will also give the halftone base a shot in my base white, you got me curious.
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on the wilflex performance inks, they recommend a product called Viscosity Buster...
we use that with the perf-white and it works great... add in about 2-3% and we're good to go with double bevels... without adding it, we have to add pressure... we've tried it with their HO inks and it works great too.
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First a comment on ink flow/stirring.
All Inks are tested in the lab before being released to the public. All viscocity testing is done with the ink at 72 degrees fahrenheit. This is why you see proper print characteristics when the ink is warm. That's how it is tested.
Now a very quick very very basic breakdown on ink chemistry.
Viscocity Buster = Plasticiser
Curable reducer = Resin and Plasticiser. No Filler. No thickener.
Chino Base, Fashion Soft, etc... = Resin, Plasticiser, some filler for effects, and very little thickening agent like Cabosil (Fumed Silica). They are all a little thicker than standard Curable Reducer.
Ink Bases = Resin, Plasticiser, some filler ingredients for rheological/adhesive/opacity/flashing purposes. Thickeners for desired effects/rheology.
Finished inks = Resin, Plasticiser, filler ingredients, thickeners, and supporting chemicals based on end use.
Quickest way to reduce viscocity of white is by using the most fluid product available. That is plasticiser. But if you over add you end up with extended flash times and/or the potential for not curing.
Second quickest way is to add curable reducer. It has no viscocity modifications and will create flow that much faster. Yes, it can extend flash times.
3rd option is a lower viscocity base of your personal choice.
However, this is screenprinting. We all have our personal opinion on proper flow and print characteristics. If I get my best print characteristics by using curable reducer and someone else gets their best print characteristics by adding the thickest base known to man. Then they are both correct answers.
I believe the reason why Alan went with the base in his white is because it improves the screen shear of the ink while also keeping it's viscocity low and rolling just enough. Curable reducer does not change drag/shear qualities of an ink.
The short answer on the Street Fighter ink. It's inconsistent. I have been using it for the last year and it..... frustrates me. Sometimes it's "runny" lower visc. Sometimes it's very short bodied and reminds me of old XOLB-158. Most of you will understand that reference. Flash times on the SF are not consistent as well as the opacity.
Conclusion, it is a cheap white. A Very Good cheap white. As a result, you learn to work with it, or search for a new white..... like me.
My 2 cents.
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I would advise most of you who haven't done it already, copy/paste Colin's post onto something you can save and keep for future reference, that's some golden info.
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I've been using Wilflex Epic Quick white lately..... it has a quality that I describe as "waxy". It seems to be full bodied, but yet pushes threw the mesh cleanly and the print doesn't get stippled when lifting the screen. I don't know what ink component provides that property, but I don't mind paying extra for it. It does climb the squeegee a little .... but not as much as a QCM158.
I need to get some screens meshed up with thin thread to see how close I can get to the proverbial "one hit".
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Damn good info Colin.
Could you imagine having an ink tech/chemist on your production floor? Luckiest boss ever.
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Thanks for the Kudos guys! :)
EB, there are still a few things that have stumped me with Rutlands inks. Stuff that just shouldn't happen at certain temp ranges with wet on wet sim process printing. But I guess it's now a new world of chemistry out there..... grrrr.
Side note: Wish I could get the garment saturation I need with waterbase/discharge inks for 50/55 lpi sim process printing :) Make all the plastisol issues go away ;)
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I wonder if some auto users assume only the screen and pallet need to be in the same plane (parallel)... but overlook the fact that the squeegee track also needs to be paralleled to the same plane.
I'm a big fan of YouTube videos for tutorial and use it for just about every car repair I make.
I put a tutorial on YouTube about adjusting (paralleling) a TUF Javelin. I'm not proud of it (and will probably remove it as soon as there's a better one available)... for now it's gonna have to suffice.
! Private video (http://www.youtube.com/watch?v=oacOCWdbtSY#)
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Northland, this is great...
Barring too many print jobs this weekend, I'm gonna be doing this to mine... I know that I only leveled the base, not print table...
-J
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Colin~
There was the video series on the high solids acrylic H2O base ink.
He was practically writing the book on the new acrylic H2O...
Remember the US guy that prints overseas?
Where / who was that again guy's?
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I avoid using viscosity buster at all costs and only use it as a very last resort. It does work great as expected but man will it jack your flash times, I have added less than recommended amounts and still seen an increase in flash time.
I seriously have to take a vid soon of the issue we are dealing with concerning Miamis smooth white. It is cold in our shop but not that cold yet the latest five gallon we are using we cannot in any way flood the white ink. It has so much body it actually starts forming sideways icicles behind the flood bar.
It has nothing to do with stirring it, we just printed a large job with the white and even after being stroked hundreds of times it made no difference.
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I wonder if some auto users assume only the screen and pallet need to be in the same plane (parallel)... but overlook the fact that the squeegee track also needs to be paralleled to the same plane.
I'm a big fan of YouTube videos for tutorial and use it for just about every car repair I make.
I put a tutorial on YouTube about adjusting (paralleling) a TUF Javelin. I'm not proud of it (and will probably remove it as soon as there's a better one available)... for now it's gonna have to suffice.
! Private video ([url]http://www.youtube.com/watch?v=oacOCWdbtSY#[/url])
That's why the flood bar mounted with dial indicators works so well for us. The pallets and screen holders do need to be in plane, but not just to each other. With all three in parallel you'll never have a favorite pallet to test print on or a favorite print head, they're all equal.
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Colin~
There was the video series on the high solids acrylic H2O base ink.
He was practically writing the book on the new acrylic H2O...
Remember the US guy that prints overseas?
Where / who was that again guy's?
Mark Gervais
Part 1 of 6 - Waterbased PVC-Free Alternatives - Separations/Film Output (http://www.youtube.com/watch?v=7zPnRK-Ei_Q#ws)
The main issue with the High Solids Acrylic is that it is low to medium opacity. So the shops that are doing really excellent work have 16+ heads and multiple flash units for p/f/p of certain colors. You WANT to run with hot pallets around 150+ degrees.... backwards thinking compared to plastisol :)
We won't print with it in our shop. Plastisol and waterbase/discharge is where we will stay until the chemistry improves in the alternate ink types.
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Actually Union`s HSA white is anything then low or medium opaque. The few times we used it through high mesh counts it has been very opaque. Drys in the screen very quick though.
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Thanks for the Kudos guys! :)
EB, there are still a few things that have stumped me with Rutlands inks. Stuff that just shouldn't happen at certain temp ranges with wet on wet sim process printing. But I guess it's now a new world of chemistry out there..... grrrr.
Side note: Wish I could get the garment saturation I need with waterbase/discharge inks for 50/55 lpi sim process printing :) Make all the plastisol issues go away ;)
Hard to state this without it coming out the wrong way but we have been printing sim/ true process DC
for a very long time without issue and no special "tricks". It does indeed take many issues away and changes some the basic fundamental tenets that have been drilled into us such as tension, dot gain, and off contact. We have executed a few experiments and have found the plastisol vs of the same graphic took longer to dial in and exhibited a lesser quality print. I won't bore everyone with previously posted pics but it really isn't that hard at all. When done correctly no dots visible even under a loupe.
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I have seen your work Tony, and I am truly impressed. Always have been. You have knowledge I want :)
The problem I am having is the standard garment types PC61, G2000, 6.1 ounce garments etc.... I just cannot get the saturation I need to remove the last hint of shirt color from between the weave. On ring spun Next level/Bella/Etc fashion garments (4.5 ounce etc ) I have much greater success, but it is still not as bright as I would wish. I am using 225 mesh and 65/90/65 blades.
Side note: We are at the tail end of a 26k order with a simprocess front, very bright bright print. Think bright yellow yellows and deep rich reds with the gamut of orange between.... we wanted to print as discharge.... but could not get the print nearly bright enough. Easy peasy with plastisol....
The only time I was happy was when I had two colors with a heavy overlap/blend that gave me the saturation I needed. Again 6.1 ounce garments.
We are using screens stretched between 25-30 (closer to 30) newtons as that's where we want them for plastisol. I understand lower tension and close to zero off contact is better for saturation, but...
I have been toying with the idea of creating a "discharge base" like a white plate that would "prime" the area so I had better shirt color removal. However, these types of jobs come in rarely.
I would actually pay for a discharge walk through on how to achieve proper saturation, color blending, separation techniques (the differences between waterbase and plastisol) Screen prep, etc.. for sim process across all garment types/weights.
Sorry to shift the topic guys!
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Sometimes it's very short bodied and reminds me of old XOLB-158. Most of you will understand that reference.
Yup. Too well actually
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And I would pay for that as well, Colin!
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I would pay too... we're doing more and more discharge these days, and I hate the raw experimentation that seems to come along with it.
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First a comment on ink flow/stirring.
All Inks are tested in the lab before being released to the public. All viscocity testing is done with the ink at 72 degrees fahrenheit. This is why you see proper print characteristics when the ink is warm. That's how it is tested.
Now a very quick very very basic breakdown on ink chemistry.
Viscocity Buster = Plasticiser
Curable reducer = Resin and Plasticiser. No Filler. No thickener.
Chino Base, Fashion Soft, etc... = Resin, Plasticiser, some filler for effects, and very little thickening agent like Cabosil (Fumed Silica). They are all a little thicker than standard Curable Reducer.
Ink Bases = Resin, Plasticiser, some filler ingredients for rheological/adhesive/opacity/flashing purposes. Thickeners for desired effects/rheology.
Finished inks = Resin, Plasticiser, filler ingredients, thickeners, and supporting chemicals based on end use.
Quickest way to reduce viscocity of white is by using the most fluid product available. That is plasticiser. But if you over add you end up with extended flash times and/or the potential for not curing.
Second quickest way is to add curable reducer. It has no viscocity modifications and will create flow that much faster. Yes, it can extend flash times.
3rd option is a lower viscocity base of your personal choice.
However, this is screenprinting. We all have our personal opinion on proper flow and print characteristics. If I get my best print characteristics by using curable reducer and someone else gets their best print characteristics by adding the thickest base known to man. Then they are both correct answers.
I believe the reason why Alan went with the base in his white is because it improves the screen shear of the ink while also keeping it's viscocity low and rolling just enough. Curable reducer does not change drag/shear qualities of an ink.
The short answer on the Street Fighter ink. It's inconsistent. I have been using it for the last year and it..... frustrates me. Sometimes it's "runny" lower visc. Sometimes it's very short bodied and reminds me of old XOLB-158. Most of you will understand that reference. Flash times on the SF are not consistent as well as the opacity.
Conclusion, it is a cheap white. A Very Good cheap white. As a result, you learn to work with it, or search for a new white..... like me.
My 2 cents.
Awesome info Colin. Here's a "technical" question. What additive makes white inks "stringy"? I have noticed most 100% poly inks are super stringy and flow/roll well on the flood. The short-bodied 158 of course would never do that. The LAST 5 gallon of Miami Superior white I had was stringy, but this 5 gallon is certainly not, it's thicker than 158. It now lives in the exposure closet with a heater on for the winter, I have added curable reducer to get it to flow and mixed the living hell out of it but it does lack the sheer that the previous bucket had. I think it had to do with the stringy-ness (technical term)?
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I'd pay for some info in discharge. It's gotta be cheaper then the amount of wasted garments that I have at the end of every discharge job. I probably look like a sketchy cat after most of the discharge jobs we've run. Just saw a discharge job come in yesterday and my blood pressure is already rising.
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I'd love to know what makes an ink long bodied and short bodied as well. There isn't (I haven't found one yet so doesn't mean it doesn't exist) a poly ink that I've tried that has a short body to it therefore they are all extrudable and more difficult to work with. They do tend to matte down the fibers and cover really well but a short bodied white is ejectable and therefore shears from the screen with ease and is more desirable when reaching for maximum opacity with one stroke. Whatever makes the poly ink bleed resistant is making the ink long and stringy, that much I do know, but I can't wait for Colin to comment on this.
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I'd love to know what makes an ink long bodied and short bodied as well. There isn't (I haven't found one yet so doesn't mean it doesn't exist) a poly ink that I've tried that has a short body to it therefore they are all extrudable and more difficult to work with. They do tend to matte down the fibers and cover really well but a short bodied white is ejectable and therefore shears from the screen with ease and is more desirable when reaching for maximum opacity with one stroke. Whatever makes the poly ink bleed resistant is making the ink long and stringy, that much I do know, but I can't wait for Colin to comment on this.
I agree that poly inks are a little harder/slower to move across the screen, but the last fiver of Miami had a little string to it and was, for lack of a better word, creamy? I went down great with one hit, sheered perfectly. This new fiver is a completely different ink and I'm struggling now to add things to it to "fix" it and get through the damn ink. Softee base is going in today and I'm going to do a full drilling top to bottom, there's about 50% left. The drill is going to hate life today.
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I'd love to know what makes an ink long bodied and short bodied as well. There isn't (I haven't found one yet so doesn't mean it doesn't exist) a poly ink that I've tried that has a short body to it therefore they are all extrudable and more difficult to work with. They do tend to matte down the fibers and cover really well but a short bodied white is ejectable and therefore shears from the screen with ease and is more desirable when reaching for maximum opacity with one stroke. Whatever makes the poly ink bleed resistant is making the ink long and stringy, that much I do know, but I can't wait for Colin to comment on this.
I agree that poly inks are a little harder/slower to move across the screen, but the last fiver of Miami had a little string to it and was, for lack of a better word, creamy? I went down great with one hit, sheered perfectly. This new fiver is a completely different ink and I'm struggling now to add things to it to "fix" it and get through the damn ink. Softee base is going in today and I'm going to do a full drilling top to bottom, there's about 50% left. The drill is going to hate life today.
Wow it sounds like me and you got ink from the same batch. I am almost at the point of shelving it and not using it again, or mixing some poly white into it.
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Wow it sounds like me and you got ink from the same batch. I am almost at the point of shelving it and not using it again, or mixing some poly white into it.
Yeah it got exponentially worse with the colder shop temps even after keeping it in a heated room.
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The "length"/"stringy" Vs. a short bodied ink is, essentially, alllll about resin choices. That is where the Great Majority those properties come from. Drag is also imparted by resin choices. Shear is imparted through several sources working in combination....
There are a couple additives that can help mitigate Some of the drag, but not all. Also, plasticiser has a small impact on rheology to a point. There are thicker (higher viscosity) and thinner (lower viscosity) plasticisers available. The thicker ones can impact drag and how stringy an ink is in very minor ways. Same thing with other additives. The additives also impact whether or not an ink will climb the squeegee or stay down and roll..... lots of combinations that can impact ink "flow" or "slump" - how well an ink relaxes on the squeegee and slides down instead of climbing.
Primarily it is a resin choice. The resins that do best for High Adhesion to poly and nylon have stringy/long properties. Also resins that help with bleed resistance have those properties as well.
Another thing to look at with the Miami White.... is did it get to hot? Heat in either manufacturing or transport can make an ink soooo thick it is almost unusable even after heavy modification.
Always contact your supplier or the manufacturer and have them check the batch number.
Damn, gotta run out the door for work.
Have a good one!
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I've gotten white inks from the biggest ink manufacturers that have become unstable for no apparent reason so it's not just limited to the Miami whites. I know those guys say their inks are always stable and won't lose anything as long as you stir them regularly but even the best inks have broken down prematurely in our shop. They start out creamy and nice but then become stringy like chewed bubble gum.
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They won't admit it but most (pls) ink companies buy their raw materials from a very large ink company which will remain nameless. Also not discussed in availabity of said raw materials and their consistencies and occaisionally lack thereof. Which (also not talked about) can result in re-formulation.
When thats done the ink runs through the usual testing for viscocity, opacity, and other rheological traits. Except, as printers, we pick up on things that they miss. Adding puff to a white is a well known bandaid to make up for weak raw materials for instance.
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They won't admit it but most (pls) ink companies buy their raw materials from a very large ink company which will remain nameless. Also not discussed in availabity of said raw materials and their consistencies and occaisionally lack thereof. Which (also not talked about) can result in re-formulation.
When thats done the ink runs through the usual testing for viscocity, opacity, and other rheological traits. Except, as printers, we pick up on things that they miss. Adding puff to a white is a well known bandaid to make up for weak raw materials for instance.
Good info as usual Tony. The amount of inks we've used the last year and the fact that so many of them are almost identical in body and opacity makes it easy to believe it's being made from the exact same materials. I'm sure we'd be very surpised with all of the secrets of the ink industry.
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They won't admit it but most (pls) ink companies buy their raw materials from a very large ink company which will remain nameless. Also not discussed in availabity of said raw materials and their consistencies and occaisionally lack thereof. Which (also not talked about) can result in re-formulation.
When thats done the ink runs through the usual testing for viscocity, opacity, and other rheological traits. Except, as printers, we pick up on things that they miss. Adding puff to a white is a well known bandaid to make up for weak raw materials for instance.
Good info as usual Tony. The amount of inks we've used the last year and the fact that so many of them are almost identical in body and opacity makes it easy to believe it's being made from the exact same materials. I'm sure we'd be very surpised with all of the secrets of the ink industry.
I's say exact same materials and "EXACT same methods and controls" every time. That's where I think the major 3-4 ink
companies are ahead of others. Especially an ISO certified company. I wonder other than the majors, how many are certified.
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Colin, knowing you ink history, you can also field this question. Why do batches differ, if ingredients remain the same? Back when I used 158 exclusively on the manual, we'd get varying buckets here and there. Do you think it was the environment the ink was stored in prior to printing? Do the base ingredients vary from the supplier? Are they tested in some way for purity before making ink? Honestly, if the technology isn't changing, and formulas are solid, then I'd point the finger at the base ingredient supplier.
It's all just chemistry, right? I want a Breaking Bad Walter White - White!
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I wonder if how they process the raw materials males a difference.
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The process I would imagine plays a huge role such as how long or how short they grind the raw materials. How they measure additives, which mixer they use etc etc probably all plays into it as well as probably what tempature/time of year they are doing there grinding, how much tolerance do they allow in the QC process etc etc.
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The process I would imagine plays a huge role such as how long or how short they grind the raw materials. How they measure additives, which mixer they use etc etc probably all plays into it as well as probably what tempature/time of year they are doing there grinding, how much tolerance do they allow in the QC process etc etc.
Well yea.. But not how long or how short the grind. But how big or how small the grind..
The ideal grind should get along "swimmingly" with the lubricant (plasticizer). But if the grind is of the bigger size then the particles start to clump together and the plasticizer begins to get absorbed by them so the inks begin to age (tack up) in a period of days after manufacturing and is responsible for the increase in viscosity.
The ink builder knows the larger grind and lesser quality materials will age, so they go beyond the ideal 34% lubricant (plasticizer) to help lower the inks viscosity but it cannot stop the aging.. So high tack and less than stellar opacity inks is the result.
When we struggle with the inks, we add more lubricant (cureable reducer) to the ink. That added lubicant also does not stop the aging so we get plasticizer overload.. Now it's phase separation, ink buildup below screens, a drop in opacity because of phase separation- the ink resin clings to the mesh walls and the plasticizer soaks into the shirt.. damn.. now what? trouble with the extra lubricant- increase in cure times..
There are three types of grind processes, the finest grind costing the most (equipment wise). I can't remember their names.
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I thought the ideal percentage of plasticizer was 35% :)
Awesome stuff once again but it's on a thread that nobody will likely find it when looking for ink info.
Looks like we have more than one plastisol ink chemist on the forum, never can have too many of those.
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Here is a real good analogy.
When putting together raw materials for baking bread, do you always add all the liquid in the recipe? Or do you slowly add in your liquids until the dough is juuuuust right? Usually having some liquids left over and occasionally needing to add a little more water to the mix.... The problem with using flour in a recipe is that the flour does not always absorb the same amount of liquid..... There are reasons for that, but I am using it for this analogy.
The same thing happens when putting together raw materials in ink. From batch to batch of raw ingredient, their absorption rates will change.
Example: White pigment TiO2. Each production batch will absorb plasticizer differently. The pigment itself can act as a thickening agent in the ink. Think about that.... the pigments you use can create a viscosity difference.
So, you have a formula, you grab all your ingredients, mix away and it's perfect. Day 2, do the same thing and you have to add a little more plastisizer to loosen up the ink during QC. Day 7, new raw ingredients come in, you grab your ingredients, mix away and it's waaaaaay to thin. You then add either resin or thickening agent depending on how the ink is behaving and the balance of that individual formula.
I.e...... we wish it was consistant, trust us.
Starchild. Most RFU inks go out the door at a 4/4.5 grind. High end whites and mixing system colors will go out at 5/5.5..... the finer the grind the looser the ink feels, very droopy.... It's rheology changes dramatically the higher the grind. Also, how well an ink ages depends on more things than just the plasticizer level. But that goes beyond and industry forum discussion.
We do not typically need to go above a 5 grind for textile inks. This grind will pass through 300 mesh easily.
Also, you can then mill roll the ink after it is mixed together... this changes the molecular structure of the inks, making them very creamy and shorter bodied. We had 4 of them at QCM and is the main reason we were purchased. They are not cheap.