The Screen Printer Donut Probe
The Screen Printer Donut Probe is there to measure control our dryer temperature, from the beginning to the end.
The Donut probe for screen printers measures the exact temperature, on the printed t-shirt, so that the print is guaranteed wash resistant. That’s why people complain about their printing ink, “oh my ink is not good”. No, it’s not your ink, it’s your curing! This is one of the most common problems that occur with a screen printer, that the wash resistance is not sufficient, because they don’t cure their printing ink properly. With the donut probe for the screen printer, we have a tool that shows us exactly what temperature is acting on our print and when the proper temperature occurs.
Plastisol inks, usually fix at 160C within a second. In comparison, water-based inks need much longer. On average you can say 160C for 3 minutes!
Suppose you put a printed t-shirt in the dryer, which is 170C. Does this mean that the t-shirt has now also directly 170C? As nicely illustrated in the video, it takes a long time to reach the desired temperature. And with water-based screen printing inks, it then takes another 3 minutes until it is really fixed. And here we are talking about normal ink applications. High-density prints have to be fixed, whereby the ink application is much higher. Therefore the donut probe helps us to know how long the goods have been at what temperature.
Donut Probe dryer mapping
But you can do even more with the donut probe. Mapp, your dryer, means, you place the donut probe in the middle of the dryer and let it run through. Note down every 5-10sec the measured temperature. Now do the same, when you place the donut probe on the left side of the dryer and the same again from the right side.
First, you won’t believe how different the temperature is in your dryer. For example, most dryers do not have the same temperature on every side or just a good temperature in the centre. But its important, to know. If you get the proper temperature in the centre, but not at the sides, which means you can’t cure your garment on the sited of the dryer, you will need to place it in the centre.
Even you can notices temperature drops, at some points. When this happens, mostly one cure panel is broken, or the airflow nozzles are blocked with dirt.
Your dryer should have a good consistency airflow all over, especially for water-based printing inks. Therefore by curing these inks, you force the water out of the screen printing ink, and this humidity you should get out of the dryer!
A Investment to control Variables
Moreover, if you think a donut probe for a screen printer is expensive, have in mind, how much it would cost you. Suppose you get a claim from a client, where the garments have not been fixed properly. Please don’t tell me, errors happen, by human and machines, minimize it as you can. Therefore the Donut Probe for screen printers is a tool to control your variables, which is a must if you would like to Screen Print like a Professional.
When to use the Screen Printer Donut Probe
1) First, to check the dryer Temperature from the inlet to the outlet
2) Secondly, to detect defective heating elements in the dryer by mapping the dryer.
3) and thirdly to ensure that your ink gets the proper temperature for the recommended time and please remember, water-based ink and Plastisol inks cure differently.
Infrared Temperature Gun
Also, to mention, the very often used Infrared Temperature gun in the screen printing department. In contrast to the donut probe. An Infrared temperature gun, is NOT a replacement for the donut probe, in no way!
Screen Printer Donut Probe – Important to know
As a matter of fact, most Plastisol inks cure by 160C (320F) in 1 second, this is not the same by water-based inks. Again, most water-based screen printing ink take up to 3 minutes by 160C (320F)
In conclusion, the donut probe assures you, that your oven has the proper temperature and that it gets the proper temperature for the time and it’s used for the dryer profiling.
The manufacturer of well-known Donut Probe for Screen Printer is AquaTuff Atkins (opens in a new tab).
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