screen printing > Equipment

Measuring shirt temp?

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killergraphics:
To be honest no.

I can pretty much tell by the feel of the shirt on exit.

The way my dryer sits even on a windy open door day.

It is ok.

My Cinnie dryer has three cow rods and I can look inside to see if they are working or not.

My first few dryers were IR's and digital. Themos going out and burning wire ends off and god forbid replacing a digital controller.

For me a precentage hot rod dryer is just better with less to go wrong.

ftembroidery:
I've used both the donut probe and the non-contact gun.  While a gentleman & I got into a lengthy back & forth "discussion" on one of the boards once about the accuracy of non-contact temperature guns, the non-contact gun IS accurate when close to the object being tested.

I would reach inside the dryer (a fore-arms length) and take the temp of the ink (the gun had a laser "pointer" feature so I knew where it was pointed) with the gun an inch or two from the shirt.  The reason I reached in was on my dryer (Hix) there was an area at the end of the heat chamber that was isolated from the heat.  It was about 6 or 8 inches long.  If I had waited for the shirt to exit the dryer before taking its temperature, it would have already been cooling off for a period of time and given me a lower than expected reading.  I would then have increased the temp (unnessisarily) to compensate.

I also found the donut probe to be slow in responding.  My primary ink/supplies merchant told me that it had been his experience that the donut probes don't work well with short dryers (which is what I had), but they did well in long dryers.

Frog:
I have a little more time now to respond more completely.
I, too rely on my settings (a combination of panel distance, temp setting, and belt speed) learned from experience, a draft free environment, and a non-contact thermometer.
However as we all know, the readings of a non-contact thermometer are only accurate relative to other things we have learned. They are only accurate as a surface reading, and then, as Nick pointed out, more accurate the closer one is. While one may learn, that a surface reading of 390 just before exit translates to the entire ink layer having reached 310, or 325, or whatever one has found, these readings and translations even change from shirt color and ink layer differences.
The donut probe, a weighted sensor, actually sitting in a film of ink has to be more accurate.

Also, the best test is, and always has been multiple launderings.

killergraphics:
It also feels good to just have a puff of smoke right at exit. For me anyway. :o

yorkie:
Temperature guns can be VERY deceptive. Because the gun "sees" the heat, shiny things can reflect the IR light. So where you think you are measuring the ink, you are actually getting a martial reading from what the light being reflected via the ink. For a flash dryer, it is easy to get readings of 500+ degrees and still not cure the shirt, this is because the the heating elements of the dryer are being recorded.

I use the "pope" method to determine when a shirt is cured. When i see the white smoke, i know the job is done. When the shirts come out of the dryer, a short benediction (pull test) is performed to confirm the event.

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