# A Good Cure Is The Only Cure In DTG And Screen Printing



## ROYAL SAVAGE (Feb 18, 2009)

After reading a post in the Kornit section today and a post in the DTG brand section several days ago, I can’t help but address the issue of curing. The number one way to lose a customer after you successfully have delivered his custom tee shirt order is to have the ink fall off the shirt. We hear stories about this from new customers on a regular basis. People ask, “How long will the print last?” The reply from all printers should be, “as long as the shirt.” We know that’s not a reality though.
Time and temperature are the principals that govern curing. This is true whether you are printing DTG or thru screens. When I purchased my first dryer over 20 years ago, it was little more than an 18” IR panel over a conveyor belt. After washing shirt after shirt we found the right time and temperature settings – belt speed zero, temperature medium. The 18” dryer worked on plastisol ink quite well. That knowledge was reserved for later use. My 18” panel made it easy to get the right settings for each of our dryers that service multiple machines years later. 
Plastisol ink is remarkably easy to cure. Once the ink reaches 290-330º F (143-166º C) you have a complete cure. You can over cure plastisol ink, but this is an infrequent problem in most t-shirt shops. Our shop has always used temperature guns to test our cure temperatures across the belt on a daily basis. This is a solid practice to employ in any shop. We use gas fired ovens which are considered to be more efficient curing machines than electric ovens. Gas ovens evenly distribute airflow across the belt, thereby avoiding “hotspots” associated with electric dryers as they get older and the IR panels begin to fail. 
Direct-to-garment printing has a completely different set of curing circumstances. In our shops case, we can only speak to curing of Kornit printed custom tee shirts. The cure parameters are close to those in our screen print areas and we use dryers that generate enormous airflow. For Kornit water based ink, airflow must be at around 5000-5500 CFM to achieve optimum cure. Less airflow than that results in under-cured prints that may remain sticky or retain the odor of the pre-treatment solution. Tunnel time – belt speed - is related to the size of the heat chambers. The parameters we use are nearly identical to those used to cure screen printed water based inks. Under curing Kornit ink will result in lack of wash fastness and over curing will result dull color. Our motto is low and slow – low temperature and slow belt speed. The low and slow theory ensures that wash fastness is generally consistent and color remains intact. There are occasions in all water based printing where environmental factors such as heat and humidity must be considered. Adjustments to your shops environment will become intuitive.
Prior to owning Kornit equipment we experimented while beta testing several types of DTG machines that required heat pressing to cure ink. All brands of DTG with the exception of Kornit can be cured with a heat press. Despite the fundamental difference between a gas oven and a heat press, the low and slow theory will ensure better results. Don't crank up the heat press to try and go faster - it doesn't work!
Regardless of what print method you employ all inks should be cured according to the manufacturer’s technical specifications for maximum durability. Today’s ink manufacturers are all very concerned about curing and will offer free advice just for the asking.


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