The importance of pre-treatment when using DTG printing

Here at Garment Printing, we always look for ways of perfecting our DTG T-Shirt printing process. After 10 years of printing with a number of different DTG machines, including excellent machines such as the Brother GT3 series, the TexJet from Polyprint and also a number of different Kornit machines, we have come up with some expert advice which we would like to share with the printing community and with our clients who need to know that quality and service are our core objectives.

In our experience, an important part of the DTG printing process is explaining to the client how their design will be printed and the process that is involved, together with managing the customers expectations.

Firstly, it’s important to take a look at pre-treatment and why this is an incredibly important step.

DTG, or Direct to Garment printing, is essentially an inkjet printer that is printing directly onto the garment. When printing onto white, 100% cotton garments, no pre-treatment is required. Therefore, the ink will sink into the garment itself, leaving an excellent soft finish.

When printing onto dark garments, a layer of white ink is required as a primary layer and then the coloured inks are printed on top of the white layer. In order to stop the white ink from penetrating the fabric, a pretreatment liquid is applied prior to the white layer which makes the ink ‘sit’ on top of the garment.

The feel is totally different to that of a white print and the results will vary from printer to printer.

The tricky part is gauging how much pretreatment should be applied and this will depend on a number of different factors:

1. The colour of the garments you are printing onto.
2. The makeup of the garment (e.g 100% cotton, 80/20, 50/50, 100% polyester)
3. The method you are using for applying the pretreatment.

If you’re using too much pretreatment then you will notice the following will happen:

• Increased production costs and reduced margin
• A heavy rigid print
• A more visible area where the pretreatment has been applied
• The print may flake or come off in the wash
• An increase in customer complaints

If too little pretreatment is applied then you will notice the following will happen:

• The print will look faded and lack vibrancy
• The washability will not be as good as it should be
• An increase in customer complaints

There are various methods for pretreating all of which have their pros and cons.

Pretreatment gun:

Pros:

• Easy to use
• Economical
• Good for starting out

Cons:

• Inconsistent application as it will depend on the user
• Increased time and cost
• Larger area is applied so a mark may be visible outside of the print area

Pretreatment machines:

Pros:

• Easy to use
• Reasonably economical
• Even pretreatment layer
• Consistent on repeat print runs
• Factory settings for correct coverage depending on garment type and colour

Cons:

• Increased investment
• Increased work space needed
• Maintenance costs
• Larger area is applied so a mark may be visible outside of the print area

Integrated DTG and pretreatment:

Pros:

• Even pretreatment layer
• Consistent on repeat print runs
• Reduced time and quicker return on investment (ROI)

Cons:

• High investment
• Increased maintenance costs

Getting the pretreatment right is an art in itself and the process is as important as, if not more than, the actual print. An even spray with the right amount will result in a near perfect print and a very happy customer!

“We recommend test printing each design to try to get the perfect combination of pretreatment and white ink."

“We also suggest contacting the pretreatment manufacturers for advice and guidance.”