Getting a good flood on the auto?

[Prosperi-Tees]

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.

[starchild]

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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[alan802]

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.

[Colin]

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.