[theory] What makes white ink so hard to print? Part 4

[blue moon]

so one thing coming up during the testing is the body of the ink. Is it long or short?

While I am not really certain yet if my thought process is right, here is an idea of why the short body prints better than the long. . .

So the question is, "Why do we prefer Short bodied inks?"

pierre

[tonypep]

Leaving for the weekend but short laymans answer is long bodied inks are more difficult to shear therefore often need to print slower. There are fixes for this of course.

[Screened Gear]

Can some one please explain the difference in a short body to a long body ink? And if you could also give some examples of inks and manufactures?

[ScreenFoo]

Example that made sense to me was honey and cool whip--honey is long, cool whip is short.

How about tack?

[blue moon]

Leaving for the weekend but short laymans answer is long bodied inks are more difficult to shear therefore often need to print slower. There are fixes for this of course.

OK, so short body shears better. What does that mean to us and why?

pierre

[Screened Gear]

Example that made sense to me was honey and cool whip--honey is long, cool whip is short.

How about tack?

That is interesting so is Street fighter a short or long. It has alot more honey in it then it does cool whip. After it prints for a while it does start looking more like coolwhip. Im just confused now...good example of the difference that does help.

[Colin]

Jon,

Is it the SF Low Bleed or Cotton White?

LB is "runnier" and the cotton is "shorter".  We use both in the shop.

I can run at 40-50 speed on my Sportsman EXG using the Cotton SF when it's a good batch.  If it gets to short, it will just climb the squeegee and never come back down.  It will also slide out the sides of my wing floodbars.....

The benefit of a short bodied ink is it gives you the best micron for micron match of your film positive. 

I.e. if you are printing a greyscale image, you will see very verrry little dot gain.

Shorter inks allow you to use less pressure to shear the ink, leaving more on top of the garment.

The "longer" "runnier" gloppier" the ink is, the less edge detail/crispness it will give you.  Because it mushes onto your shirt, it does not shear.

The above print speed really only produces an acceptable print on good ringspun garments though.  I used a 65/90/65 sharp blade - about 40 lbs pressure 16" wide blade.  Angle is about 10 degrees for a bit more opacity.  Mesh is 150/54?  From Shurelock using their panel frames.  Tension is around 30-34 newtons.

The standard PC61/Hanes/G200 etc are more difficult to print that fast on and Maintain a clean print with good fiber matte.

We almost always will use a roller frame/smoothing screen regardless of shirt type.

Here is a flip side to short bodied inks.  MOST will also become to soft/pourable/have a large drop in centipose (cP).  The more an ink can keep it's original viscosity, the better it can keep it's opacity.



This appears to happen more often WITH PRICIER INKS

When reviewing, please keep in mind the COST OF THE INK YOU ARE WORKING WITH

SF is a very very cheap white.  It is made with Economy ingredients.  Good economy ingredients, but economy nonetheless.

Hope this helps... back to work i go....

[Screened Gear]

Jon,

Is it the SF Low Bleed or Cotton White?

LB is "runnier" and the cotton is "shorter".  We use both in the shop.

I can run at 40-50 speed on my Sportsman EXG using the Cotton SF when it's a good batch.  If it gets to short, it will just climb the squeegee and never come back down.  It will also slide out the sides of my wing floodbars.....

The benefit of a short bodied ink is it gives you the best micron for micron match of your film positive. 

I.e. if you are printing a greyscale image, you will see very verrry little dot gain.

Shorter inks allow you to use less pressure to shear the ink, leaving more on top of the garment.

The "longer" "runnier" gloppier" the ink is, the less edge detail/crispness it will give you.  Because it mushes onto your shirt, it does not shear.

The above print speed really only produces an acceptable print on good ringspun garments though.  I used a 65/90/65 sharp blade - about 40 lbs pressure 16" wide blade.  Angle is about 10 degrees for a bit more opacity.  Mesh is 150/54?  From Shurelock using their panel frames.  Tension is around 30-34 newtons.

The standard PC61/Hanes/G200 etc are more difficult to print that fast on and Maintain a clean print with good fiber matte.

We almost always will use a roller frame/smoothing screen regardless of shirt type.

Here is a flip side to short bodied inks.  MOST will also become to soft/pourable/have a large drop in centipose (cP).  The more an ink can keep it's original viscosity, the better it can keep it's opacity.



This appears to happen more often WITH PRICIER INKS

When reviewing, please keep in mind the COST OF THE INK YOU ARE WORKING WITH

SF is a very very cheap white.  It is made with Economy ingredients.  Good economy ingredients, but economy nonetheless.

Hope this helps... back to work i go....

Great detail. Thanks. I am using the LB SF2. I used to use Wiflex quick but the price kept getting higher. Not that its not worth it but when I can get 10 gallons of SF for about the same price.  They both do the job.

[mk162]

Wilflex has a new warrior white, supposed to compete with Streetfighter.

I still prefer Xtreme.  Prints great for us.

[ebscreen]

Colin, we recently got a batch of the SF cotton white that is the worst squeegee climber
I've ever seen. Do you have any recommendations to remedy the situation? My employees
tell me to send it back...

[tonypep]

I haven't dwelled on this for some time however I defer to MCs article. I don't want to beat this to death but with regards to this topic we once again find ourselves mired in a sea of interdependent variables. I can only advise those that choose to so only change one variable at a time.
Otherwise we cannot truly collect and analyze accurate data.(Example change to s mesh and see what happens) I commend my friend Pierre in his endeavor. That is as much am I allowed to contribute

[Colin]

That warrior white uses a duller white pigment and puffs a very large amount.... I dislike it

EB, the only way to change the rheology of a super short/thick ink is to add as liquid a component as possible.... this will quickly bring the stiffness down while still keeping the short properties.

Curable reducer/primer clear/fashion base etc......  I got some single gallons a few months ago - I was in a pinch and that's all they had - and all the gallons were like you describe.  Too short bodied and thicker in rheology.  It climbed the squeegee and crept out the sides of my winged flood bars.  Forcing us to stop and scoop the ink back in front of the squeegee.  If I am going to use it up, I will mix it in with a runnier white or just use it on the manual press.

Tony is correct.  There are sooo many variables involved in defining the best white ink, and only some of them have to do with chemistry.....  This is why I keep giving lots of details on my experiences and I ask for more details from people relating theirs...

Tony: I would love to see a day where you have no workplace/contract constraints on your comments and experience.

[tonypep]

Thanks Colin. To clarify, as Director of Ops and a senior manager of this company I am duty bound to post with restraint. I will always remain loyal to my company and it is simply the right thing to do.

[ScreenFoo]

EB:  FWIW, I've had great luck using halftone base to get white to flood well, it doesn't take much, (could be not even 1% by weight) and it doesn't seem to change the mat down or opacity--or at least, not enough for me to notice. 

I keep thinking a straight plasticiser would be what you'd REALLY want, but I know how much that can screw around with cure/flash properties... not to mention what it does to how it prints.

[blue moon]

OK, so many good points, but I am going to try to reel this in and return to the less practical and more theoretical discussion.

We all keep saying it prints better and shears better, but what does that mean? The shearing is happening on the top of the screen and the print is underneath. That sounds like we are not really shearing it! Or are we?

Pierre