How long does the ink need to be at cure temp?

[Dottonedan]

So, I’m having issue with a Dreyer not reaching 320 at a decent dryer temp. I’ve got to increase from 450 to now up at 490 to reach a 320 for a decent amount of time.


So I checked with Wilflex (Ray Smith) to find out if the cure temp needs to be maintained for a period of time...or does it just need to once reach 320?
He stated that it should reach 320 (for a period of 5-6 seconds). 


We are getting there now, only by lowering belt speed from 45 to 42....and upping to 490.   I originally had suspected that our temps were not right...and found we were not fully curing. So this is the result.  I assume I’d need a tech in to calibrate the panels or replace the panels. Not sure there, but this is our work around.

[inkman996]

Its a matter of allowing enough time for that cure temp to soak all the way through the ink layer.

[Frog]

Dan, how do you check temperature? Do you guys have a donut probe which could sit right in the ink deposit of a test piece, really reading the bottom of the layer.

[tonypep]

It isreferred to as retention time....sorry back from a long offsite consult but I will get back Dan. In short term it is how long a garment is retained in the dryer chamber at a set temperature.

[Sbrem]

And then there's the old "tug on it" method. I think I'd see about getting a donut probe, but you might try the temperature strips too. No matter what the setting is, what the temperature is at belt level is what's important, then the retention time.

Steve

[Rob Coleman]

Ray is correct, but that is probably worst case. The subjective answer for plastisol is 320 (or whatever cure temp) throughout the ENTIRE ink film. So printing sim process through a 305 will cure much much faster than thick athletic numbering on football jerseys.


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[Dottonedan]

Maybe you guys have seen this before and can give me some tips.
We do have a donut probe.  That’s what we’ve been testing with. My question was (how long does it really need to be at 320?). I got my answer from Ray Smith who many of you know works for Wilflex.

So yesterday, we used that donut to test the temps pretty much at the beginning, middle and end of a run of 1100 shirts.  NAVY (100% poly) from china. Customer supplied.We were just getting a small (left side) section at the end of the dryer up above 320. We were into the 350’s and the shirts were smoking coming out. So we back that down a little on the over all temp to 465 and got around the 330 for a short period of about 8-12” in length and about 5 seconds. Ray Smith from Wilflex said that should be good enough. He said 5-6 seconds at 320 should be good enough to be sure of a full cure. This particular run/print could have been done at a lower temp. I’m not even sure yet of what temp the Guardian Grey cures at.  I’m assuming a low cure temp. like 290. (designed for bleeders) but to be sure, we kept it at the 320.I’ll contact them directly.  For the Poly white, it was said to cure at about 290.Now, with that order...We were printing a white print. We were using International Coatings Guardian Grey as a base. White trying not to have to revolve, (1 flash), we printed the Grey base...and a 156 mesh TOP WHITE double stroke.  That looked good enough on press, but when it got out of the dryer....it was Blotchy. Not a consistent white. Blotchy grey areas and white areas.  (Could be the garment), and could be our printing. A lot of unknowns there.Don’t know why we have been using that Guardian grey...but thats what the Operations Mgr continued to buy. He must have had good luck with it at his previous shop. I didn’t like it in combination with Triangle Ink (Poly Excel White) we had to use...because we didn’t get our inks back from Nazdar in time...and ran too low for this order and another supplier who has been wanting us to buy from him offered to deliver...and return the Triangle Ink (Poly Excel White) 5 gallon (if it didn’t work).He traveled almost 3 hrs to bring us a 5 galling of his white to test out. This is Triangle Ink (Poly Excel White).  For me in my opinion, it didn’t seem to work that well in combination with the IC Guardian Grey base. I don’t know if it’s an INK thing, or our dryer thing.  The results were just wrong. Based on everything we were doing and using, (it should have worked) but the results looked very questionable.I will be getting the Bleed blocking Base Grey ink from (the name slips my mind), but it was a bleed blocker for sure.  People say it’s too expensive. I can’t think if the name, but I know it works on the Badger Camo’s so since those are THE worst in the business, it should be good for any other poly garment.The printer here, didn’t really want to use a 100% Poly white. He kept gravitating to using the so called “tried and true” Wilflex Epic BOLT LC white... “low cure”white...and those just aren’t the same as a Poly white. Am I wrong there?  Poly whites are designed to work on heavy Poly content...and resist bleeding but they don’t have any of that here. White Low Cure Cotton/Ply whites are just for easier garments like tri Blends that may bleed a little.  Right? they are not a solid bleed blocking white.Maybe you guys have seen this before and can give me some tips.

[prozyan]

Looks like either the top white didn't get great coverage (though as you described printing it should have been fine) or the underbase was under-flashed.

As for curing the ink, a dwell time isn't necessary.  Technically ink is fully cured with it reaches the cure temp.  The trick is, as has been mentioned, the entire ink film has to reach that temperature.  It helps to think of it like baking a large ham in the oven.  If the temperature is too high it is possible to burn the outside, yet the center remains raw.  Ink is the same way:  Too quick through a hot dryer and the surface of the ink will cure, but the ink that is in contact with the garment does not.  Slow the belt down and you scorch the shirt and the ink still doesn't cure all the way though.  Have to find that sweet spot between heat and speed.

[Steve12Lowry]

Yeah, this looks like dye migration.

For 100% poly, especially unknown fabric from China, will probably need the barrier grey plus 100% poly white.

The bolt white cures at 270, has very little bleed resistance as is, and gets even worse at higher temperatures (320). Like you said, it is better for poly/cotton and tri-blends. The guardian grey is a 275-320 cure but in my opinion, doesn't work very well at the higher temps which you needed for the Triangle poly white.

If this was me, I would go with a low cure grey/black and low cure white (Union UPLC, One Stroke ELT) or something like Rutland barrier grey and Super Poly White if you want to cure at 320.

[Sbrem]

We recently tested and switched to International Coatings Guardian Gray, 7403, and are getting great results with it. But we haven't run into any suspect fabrics such as the Chinese item you're having to deal with.

Steve

[Dottonedan]

Thanks all!


Today, we are running another order (just like the previous).  I spoke with a guy at Avient (Not Ray) about this issue and the garments and dwell time.  He suggested to for sure use. a 100% poly over using the Bolt.
but it all comes down to the length of dwell time...(approximately 60 seconds) at near cure temps and for at least 5-7 seconds at cure temp.


So today, using both a 156 on base...and a 156 on top white, we are using BOLT that just came in. Now, BOLT as someone mentioned dis not really designed for major bleeders. But, it does have some bleed resistance and can be used if used right. THIS, is turning out BETTER than using the IC Grey bleed blocker....and I had read on there own website that the IC Bleed blocker...is very sensitive..and you have to have the right finesse (not overly flashed, and not under flashed....or it will do just what you are seeing in that pic above. Sort of melt in the top white...or will create some meshing with there top if it’s under flashed. Our flash doesn’t go in fractions of a second and the press op thought maybe they did over flash a bit.


So, using the donut, we tested and timed the dwell with the temp...and reached an actual cure....with a slower belt speed and lower temp (435) and belt speed at 35....reaching the 1 min, and the temps staying a more consistent and longer length of this 280-290 range. Voila!   Stretch test past, and remains a bright white. Now, letting it cool off before stacking is another thing we will be doing for this order.  These shirts are just too tricky to get done fast and hot.


In addition, he mentioned another tip.
(when using a fan to cool off) we should set it at the top of the dryer, facing down to blow the heat down. while also holds the heat back in the chamber.  If you set it to the side and angled out away from the dryer (like we were yesterday), it pulls more heat out of the dryer decreasing your exit temp.  Obviously cool off the shirts quickly and don’t stack them even hot or even warm. Get them to room temp. Break them out into stacks across a huge table (we have) and allow them a couple more seconds to get room temp.