Top 10 Best Practices when Printing Polyester
1. Research Your Garment
Look at the fiber composition, the color of the garment, the stretch of the garment, the functionality of the garment and the weave and texture of the garment. Then decide what ink is needed. Is it necessary to have bleed resistance, extra adhesion, elongation, both bleed resistance and elongation or both extra adhesion and elongation? While deciding what ink is best for the job, make sure to understand the limitations of the ink and the garment.
2. Always Pre-test New Garments and Fabric Dye Lots for Excessive Migration
We always recommend pretesting before you start a print job. Follow our Bleed Test procedures for best results.
3. Avoid Additives to Your Low Bleed Inks
The addition of a catalyst is not effective in reducing dye migration and will reduce elongation/stretch of ink film. Adding reducers will compromise the effectiveness of your low bleed inks.
4. Take Special Care Preparing Your Stencil
Make sure to have a defined edge on the shirt side of your stencil. This creates a dam for better ink transfer. For direct coating, we recommend two over two coating. For capillary: 30+ micron.
5. Set It Up for Success
Use consistent, tensioned screen mesh: 25-35 n/cm2 recommended.
Off Contact Settings: Auto -1/16” (1 ½ mm), Manual -1/8” (3 mm)
Gel Temperature: Select Low Bleed, Lower Gel Inks: Epic Top Score and Performance gel @ 220 F (104 C)
Cure Temperature: Select Low Bleed, Lower Cure: Epic Top Score and Performance 290 F (160 C
If using pre-stir ink and printing on a hard surface, use a palette covering to allow for softer printing surface.
6. Do Not Undercure or Overcure
Under-curing allows the fugitive dyes in the polyester to migrate to the surface. The dyes have a natural infinity for plasticizers in the inks and will actually draw the dyes to the ink surface. If the garment shows an immediate bleed – it is possible that the dryer is too hot, or the garment is staying in the heat chamber too long, or the need for a more bleed resistant ink is needed. A solution is to map your dryer, then set your dyer belt to run as quickly as possible while still achieving the required temperature needed for full cure.
7. Avoid Excessive Temperature Spikes
The flash-curing unit has proven to be the biggest cause of dye migration, with electric IR dryers coming in second and gas dryers being the least problematic. Problems stem from failing to adjust flashing parameters for particular jobs, shop conditions, or ink types and deposit thicknesses. The best solution for IR dryers is to balance dryer belt speed and temperature settings to provide the lowest amount of heat exposure that will result in successfully cured prints. Top Score Inks cure at 290F.
8. Beware of Ghostly Results
Avoid stacking products while hot. Ghosting or post bleaching can occur on light colored, over dyed or stone washed garments when printing with low bleed inks. Ghosting occurs when all three conditions exist:
- certain dye stuffs
- moisture in garment
- heat retention
Fabric and dye characteristics can exhibit variance between manufacturers and from dye lot to lot. Follow our Fabric Discoloration Test for best results.
9. Improving Opacity
Ink Selection is always important. Make sure you are printing with a high opacity ink like Epic Top Score.
- Print on the surface of the substrate – do not push into the substrate
- Thick stencil
- Hard Flood
- Print with low-pressure, low angle
- Square, Soft Squeegee
10. Increasing Production Speeds
To increase production speeds, use finer mesh counts for the flash plate to decrease gel time. Set flash dwell times on heated pallets to simulate production. Adjust your setting so that the ink is just dry to the touch.