An overview of pretreat for DTG printing
For direct to garment printers, such as the Epson F2100 and F3070, pretreat is a key component. For dark garments, the printers will lay down a layer of white ink so the color that prints afterwards has a neutral base. Pretreat prevents the fabric from soaking up the ink too much, which makes the image very poor. In other words, it allows the ink to display on the shirt as intended, instead of being absorbed. It's crucial for image quality with multiple layers of ink, which is used for darker garments.
The pretreat machine is a crucial piece of applying this solution evenly and consistently to garments. Trying to get consistent results from other methods, like a roller or spray bottle, will leave most shirts with uneven amounts of pretreat and a lot of wasted prints or poor quality images. The pretreat machines are also fast and easy to maintain.
Another solution is to purchase "RTP" shirts that have already been treated by the manufacturer. This makes the process very simple, but limits your garment options and gives you no control over the pretreat process. Another thing to keep in mind is that you don't have to pretreat white or light shirts if you are not putting down the extra layer of white as a base (although you can put white down on any color shirt if desired). Often times, when the image quality is not ideal, a lack of proper pretreatment application is the culprit. Feel free to reach out to Grimco with more questions!