The purpose of pretreatment is to create a flat smooth surface on your garment so that ink can be applied to and adhere to the garment with the least amount of distortion in the print due to imperfections in the textile itself. Keep in mind that all textiles have some amount of fuzz or lint on their surface. Also, as all textiles are an interlacing of fabric (of some kind), so the surface of the garment has many valleys and gaps (even if you cannot see them). The ink that is being applied to the garment is being done on a very small scale, meaning that the ink droplets themselves can fall into those imperfections on the textile creating a less than quality printed image to the naked eye. This is why prints on paper can appear so photo realistic while a print on a wool blanket would not retain the same level of crisp clarity that the same print would on a smooth surface (piece of paper). This is due to the nature of the material itself and it's overall surface properties when ink sits on top of it and drys.
In addition to the indentations in fabric (the valleys and gaps due to the weave of the fabric) it is also possible that the fuzz from the textile itself may sit on top of the garment creating little mountains of fuzz. This can create that same distorted effect when printing.
The key to pretreatment is:
- Apply an evenly distributed amount of pre-treatment solution using an synthetic roller.
- Use the pretreatment and roller to flatten and smooth the surface of the garment.
- Roll in one direction preferably with the grain of the fabric to ensure no textile fuzz or imperfections in the weave of the fabric stick up.
Pre-treatment is generally used in dark garment printing. As discussed in the Process Printing section, the color of the material that you are printing on will impact the final appearance of the print because direct to garment printing uses a subtractive color model. This means that in order to obtain the crispest colors possible on a dark garment, you need to create a white background on the garment. As discussed in the general section, all textiles have imperfections in their surface where ink can fall and distort the final image to the naked eye. In order to avoid this you need to create both a smooth surface to print your white background on and a surface with some additional adhesive qualities. The solution is to use pre-treatment in your dark garment printing process.
You should have a well ventilated room, a large flat surface for prep, and a container for your pretreatment solution.
Lightly apply the pre-treatment solution to the shirt using the roller provided. Make sure that the print area becomes visibly damp, but not overly saturated. As long as total coverage is achieved, less pre-treatment is better for wash fastness and color vibrancy than too much pre-treatment.
- Make sure the heat press is set at the following settings:
- 45 secs
- High Pressure (80psi) or the number 7, 8 or 9 displayed on the new automatic heat presses. Reduce the pressure if the pretreat does not wash out.
- Heat set the blank shirt for 10 seconds; this will remove excess moisture and flatten the fibers while assisting with a smooth re-treatment application. Use a fresh sheet of silicone coated parchment or kraft paper.
- The shirt collar should be to the front; the fibers lay down from top to bottom (collar to bottom of shirt).
- Shake the pretreatment solution well to remove settling.
- Pour enough pretreatment into a paint pan.
- Soak roller (do not over saturate).
- Apply the pretreatment by rolling in one direction from neck to bottom of shirt or desired coverage area (one direction only; no forward and backward roll); apply a medium pressure to ensure that the pretreatment is getting into the fiber.
- Overlap the roll; dip the roller into pretreatment solution as needed.
- Hover the heat press over the shirt for 10 seconds.
- Cover the shirt with coated Kraft or parchment paper and close press.
- Remove shirt after 45 secs or when the steam disappears.
- Re-press for another 10 to 15 seconds if the shirt is still wet; this means you are applying too much pretreatment.
Note: excess pretreatment will come out after the shirt is washed.
Staining On Certain Color Shirts
Some color garments such as bright orange, lime green and hot pink have dyes that react with heat; the dye migrates and a bluish/reddish stain can be seen after the shirt is cured. To prevent this, you need to follow the following steps:
- Do nor preheat garment.
- Spray the shirt down with distilled water.
- Apply pretreatment.
- Hover for 10 seconds
- Place parchment paper over garment and close heat press.
- Use the curing parameters settings for the pretreatment above.
Specific instructions on the wash method:
- Turn the shirt inside out
- Use cold water
- Dry on delicate cycle