Tuesday, October 15, 2019

DTG curing systems are different, and need to be.

Not your grandpa's t-shirt dryer

Digital printing is a specialty market requiring a new way of thinking.  Rapid production of low volume, high quality graphics is necessary to produce high profits.  The DTG printing process is different than traditional decorating.  The chemistry of the inks and pretreat require new curing temperatures and times.  They also need a different type of cure.  Traditional IR heat with a little moving air just doesn't do the job.  This technology is designed for plastisol and, though it can be used for DTG, it will not give the best results.

So what's different?

Let's start with pretreat.  What is it?  

Pretreat is a sticky liquid that mattes the fibers into the garment to create a flat, smooth surface for printing.  Most pretreat needs to be sprayed onto the garment and then heat pressed to get the best results.  This process is slow but effective.  Conveyor ovens, if designed for the job, offer a faster process with fewer operators.  Pretreat needs heat and air.  Evaporation is essential.  So, convection heat is optimal.  The garment still needs a 3 second press after exiting the oven to flatten the fibers.  What a convection oven offers is less standing around for the operator.

Now the ink.  Water based and white under base passes make this more complicated.

Water based inks need lots of air flow and time in the chamber.  Water is slow to evaporate and the chamber needs to evacuate the water without pulling out the heat.  Temperatures are lower than plastisol but times are longer.  Traditional ovens boil the water out with direct heat and evacuate the air with standard exhaust.  

The white under base, which can have multiple passes also needs to get the water evacuated.  This increases the time in chamber but the top color passes cannot handle the extra heat, so convection air is the optimal solution as the garment temperature stays more stable.

Why not use what you have?

You can.  And we sell ovens that will work if that is your best plan.  Yes, the TRX, the UltraSierra X-Series 2, the AirBlazer and the AirPony can cure DTG inks.  And they are a lower cost than ovens specific to DTG.  So if budget is a concern, our years of experience can help you use plastisol technology for your digital prints.  

However, we do not recommend them.  

Why?  You say.  No, it's not because we want to sell higher priced stuff.  It is because the technology to cure plastisol inks is not the same as the tech to cure digital inks.  Traditional ovens, like the ones we have been building for over 30 years, are great at what they are designed for.  They ramp the temperature of the garment up as they radiate heat directly onto the ink.  The ink does not need to evaporate, it needs to cure.  Plastisol inks, generally, require a cure at 320°F through the ink film.  As long as the full ink film gets to this temperature without scorching the garment, you can go as hot and fast as possible.  Once the plastisol hits temp, it becomes a solid sheet of plastic that is adhered to the garment.  So air is a nice feature to reduce hot spots in the oven or to force air into specialty inks like puff.  However, it is not needed for cure.


Gas ovens are a possibility for both ink types.  They are convection systems that sit the garment in hot air and evacuate smoke and steam.  However, in order to get to temperature, they need to be large.  Most shops do not have the space or budget for these ovens.  They also require a large power supply in addition to the natural gas connection.  In order for the garment to get to temperature quickly, they often have an IR bump in the beginning of the chamber and this requires 240V power.

So what do you look for?

Heated air, and lots of it that is contained within a closed system that scrubs and reuses it.  Another necessity is a quick blast of heat to bring the garment up to temperature quickly.  The fast temp bump will get the garment hot before it sits in the heated air which will speed up the cure time.  Additionally, that heat needs to stay in the chamber.  So cool external walls will keep the chamber hotter and the work environment cooler.

Digital temperature controls are essential.  Since garments are in the cure chamber for a longer duration than traditional curing, maintaining the top temperature will speed up cure and avoid scorching.  Digital controls maintain chamber temperature ±7°F and this will alleviate any cure concerns.  

Belt speeds that are slower than traditional plastisol cures are warranted as well.  Our pulse generators allow for belt speeds as slow as 99 minutes in the chamber.  Plastisol cures are 30 seconds to 2 minutes.  DTG needs 2 to 6 minutes depending on passes and the amount of pretreat.  


DragonAir Core Technology

The DragonAir line of curing systems is designed for digital, water-based, plastisol, polyester, and specialty printing for fast paced, high production shops.  The DragonAir Core Technology™ ensures consistent and complete curing on all garments.

The new Crimson Dragon is designed for smaller shops with singular DTG devices.  The offer DragonAir Core Technology as well as digital temperature control in a compact footprint.  Priced for community printers, this allows a screen print shop to install a small oven just for DTG.  

The DragonAir Fire is for larger DTG producers who need additional belt space and are looking for higher end controls.  They feature TRX software for full control and storage of up to 18 separate garment profiles.

DragonAir Griffin systems are for full DTG producers.  Expandable and utilizing TRX software technology, these dragons give flexibility and durability for the ever growing digital market.

The FireFly is patented technology that goes one step beyond the Dragon line.  This revolutionary system will allow any type of garment to cure through any belt at any time.  Thermal imaging cameras monitor and adjust for each garment as it travels through the oven.

Not your grandpa's t-shirt oven because these are not printed on your grandpa's carousel.  Advancements in the industry push all of use to create new technologies to accommodate.  Look at your production facility and see if old school is still best.  It may be, or not.