# Ink opacity issues over white underbase



## deadbat (Nov 5, 2009)

I just switched to an automatic printer a couple months ago, and for the most part I've been pretty happy with the increased quality and consistency of prints I have been getting versus my manual printer.

The one issue that I have been fighting, on more than one job now, is having colors appear too light when printed over a white underbase. In particular this seems to be mostly with reds, but not exclusively.

I am printing a white underbase and flashing it, and I believe that I am flashing it sufficiently that the issue is not coming from the color being pushed down into the white, but rather with the color just not printing sufficiently opaque over the white. At first I thought it was that I was using 230 mesh screens which weren't giving me a thick enough print (even though coated 2/2), but I just ran a job where I put the color (a dark purple) on a 110 mesh screen coated 2/2 and it still wound up looking much more pink relative to the previous job I had printed for the client on my manual (on the manual I just did a print/flash on the color ink separately from the white because it was a short run). So now I need to reprint this job, but I need to figure out this issue before I do so.

I tried laying the squeegee angle down a bit, I tried double stroking it. The only thing I didn't do was actually run the job another cycle so I could flash it again and print the purple another time. That doesn't seem like a proper solution, so I am looking for suggestions for what I should be trying to fix this the "right" way.

Thanks.


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## gardenhillemb (Oct 29, 2015)

Are you sure your white ink is flashing enough. If it's not dry (not cured though), the purple or red ink will pick up some of the white from the underbase.


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## deadbat (Nov 5, 2009)

Yes, I'm sure that is not the issue because I've played with the flash time a lot, and I saw what it looked like when that happened. In the issue I'm having now, you can actually wipe the ink off and have the white ink stay on the shirt underneath. I was thinking perhaps I was actually over-flashing it, but it seems like changing the flash all the way from just-barely tacky (where the inks push down into the white) all the way up to the point where I'm basically scorching the shirt, it never resulted in an opaque print on top. 

Maybe I need to be using rounded edge squeegees for these colors?


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## dynamikgraphics (Jul 21, 2013)

What print head is the red set up on relative to the "flash" print head?

I worked for years in a shop that used a 10-head/12-station Anatol Stratus II with flash units on heads 2 & 7. As a rule of thumb (unless forced to do so), I _NEVER_ setup a color immediately after a flash, because while the ink may be drying under the flash, it's too ruddy hot coming out from under it. 

What happens is the next screen gets sandwiched against the hot ink and the ink in that screen actually "cures" a little, preventing ink from getting put down. 

If possible, put as many "off" print heads between the flash & the next color as possible. This will give the flashed print time to cool. 

If you've already accounted for this, then I'd agree with above - if ink isn't dried completely under the flash, the next color will appear "washed out." 

Run a print as normal, then stop the machine after the shirt emerges from the flash. Check to see if it's dry to the touch. 

One other note and I'll hush:

Before starting your print run, turn off all print heads and run the carousel around a few times flashing the pallets; this will warm them up, which will in turn warm the garments. Takes some of the work load off the flash unit during the first few prints.


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## deadbat (Nov 5, 2009)

Those are all great guidelines, but I've already accounted for all of those things.

After playing around quite a bit, I am starting to believe the issue may be having my off contact set too high. I'm still getting used to exactly how it works with an automatic, and I just printed a white on red job (just print flash print opaque white) and got a much nicer looking white than I was getting before, by lowering my off contact. I haven't had time to set up the next job with color over white, but my off contacts on the color screens were similar, so I feel like perhaps the squeegee was having to push down too hard to get the screen to make contact with the shirt, and so was pushing too hard on the ink while going over that smooth-ish surface of the white ink. Since the color ink couldn't be pushed *down* in the fabric by that extra pressure, it would instead wind up getting pushed along the screen surface, meaning it would put down a thinner layer.


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## dynamikgraphics (Jul 21, 2013)

deadbat said:


> Those are all great guidelines, but I've already accounted for all of those things.
> 
> After playing around quite a bit, I am starting to believe the issue may be having my off contact set too high. I'm still getting used to exactly how it works with an automatic, and I just printed a white on red job (just print flash print opaque white) and got a much nicer looking white than I was getting before, by lowering my off contact. I haven't had time to set up the next job with color over white, but my off contacts on the color screens were similar, so I feel like perhaps the squeegee was having to push down too hard to get the screen to make contact with the shirt, and so was pushing too hard on the ink while going over that smooth-ish surface of the white ink. Since the color ink couldn't be pushed *down* in the fabric by that extra pressure, it would instead wind up getting pushed along the screen surface, meaning it would put down a thinner layer.


Excellent. Sorry to bore you with all that 

Generally, off-contact shouldn't be more than 1/4" *at most. *If you can dial it in to 1/8", that'd be perfect.


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## DonR (May 6, 2011)

You can try to use a light grey underbase instead of white. I find this will help when reds appear to be pink when printed over an underbase.


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## deadbat (Nov 5, 2009)

It was not boring, it was all good advice, and since I hadn't said that I did all that already it was good to provide.


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## deadbat (Nov 5, 2009)

dynamikgraphics said:


> Generally, off-contact shouldn't be more than 1/4" *at most. *If you can dial it in to 1/8", that'd be perfect.


Actually, I looked and for the Wilflex Bright Tiger white, the manufacturer only recommends a 1/16" off contact, with a "hard flood" and a very fast print stroke. I set up my machine to match those better and got a much smoother white. Before I was using (I guess you would call it) a more "soft" flood which put a lot of ink on the screen, and was using a slower stroke thinking it would give me better coverage, but apparently the fast stroke enables more of the ink to stay on the shirt rather than pull back with the screen.


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