Periodic problem... 10/29

[DCSP John]

This issue creeps up sometimes.. mostly with blue inks...
Changing squeegee pressure, squeegee angle, speed, blade never seems to be the right fix.
There are uniform wavy lines that sometimes appear when the highlight blue is printed over an underbase...
For the life of me I cannot isolate what causes this uniform wavy pattern...
Screens nice and tight... maybe its a viscosity issue with our blue ink? Sounds like a newb issue.. but plagues
us form time to time. Any thoughts?

John

[Doug S]

If it done on every print, I'd say it's more your underbase.  That's a new one to me.

[Printficient]

Looks to me like a heat (as in too much) problem.  Could be something else.  i do not have enough info.  If you want to call me I'll figure it out.  678-412-1395

[Croft]

I get the same problem usually with blues and forest greens , usually worst on double hit white bases. We use newmans and have resorted to sometimes flashing and printing a second hit.
  I would like to figure out as well.

[DCSP John]

Strange huh? The mystery continues..

It almost as if the underbase is too smooth...

We use as minimal amount of underbase flash as possible, so I have eliminated heat as a cause..
Yep.. If we let it run, the waves would be on every print..

A quick fix is to swap ink for a thicker ink. Usually eliminates the issue. But, I see this as a band aid, and
not a real solution to the problem.

John

[3Deep]

Just taking a wild guess here it could be in the weave of the shirt, and the ink is following that pattern.  To test I would look at a shirt and see if you can see any waves and then print to see if if has that pattern or you could have a bad pallet?

Darryl

[DCSP John]

3 -

I hear you. but when this occurs we test across a variety of shirts/weaves to see if the fabric is the culprit..
Same crazy lines across all fabrics. Has to be  under base related, or top coat related...

John

[Admiral]

I had this a long time ago with panelframes, 200 mesh count on top of base (which I think was 110) using S mesh on roller frames eliminated the issue, some sort of mesh interference or dragging issue with the lower tension.  Very open squeegee angle helped it too.

Are you using a pneumatic print head? that probably makes the issue worse as well.

[GKitson]

 Blue pigments are notorious for this problem.  Increased mesh open area is the usual band-aid for this one.

Has to do with shape of blue pigments when ground and there relative transparency.


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[tonypep]

Thats correct Greg

[alan802]

Yes, the blue pigments are long and skinny while the white is round, or spherical.  The blue ink exacerbates any ink deposit inconsistencies that are probably there with other prints but not as noticeable.  Blue on top of an underbase is always touchy.

[inkman996]

We print for Goodwill HQ a lot and one repeat job requires a large blue block on the back I had the same issue the first time we ran it and I pulled my hair out of my head. switched screens several times base and the blue to no avail. I was using high mesh for the blue since it was on top of white and everytime I tried a new screen I stuck with a high mesh. Finally i got fed up with it and went with a 160 and bam waves were gone.

[tonypep]

BTW........WB/DC will fix this. Pigments are ground finer.
But you know I was going to say that!

[ZooCity]

So that's why I really prefer the WFX "super opaque" royals and blues.  Really appreciate learning stuff like this.  I would have looked at that off our air head press and figured the blade was chattering or printing inconsistently.

[ebscreen]

Yeah, never knew why it happened, just know that thickener and/or lower mesh is the fix.
I hate how runny most royals are anyways, but I guess that goes with the color.

Awesome to finally learn the science behind it.