Most sweatshirts, hoodies, and performance garments contain a percentage of polyester, for its strength and stability. It is also more colourfast than cotton in normal wash and wear.
However garments with a polyester content need more care at the high temperatures associated with screenprinting. If overheated, dye from the polyester can ‘migrate’ into the ink. This can appear immediately after the ink is cured, or hours or days later.
To prevent this:
* Print with low-bleed, high opacity inks designed for printing on fabric with a polyester content.
* Use no more heat than necessary to cure the ink; max 160 degrees C. Please be aware that with large print runs, temperature can ‘creep’ upwards – you will need to adjust as required.
* Print and flash-cure a low-bleed white or similar under base, then print the desired color.
If in doubt, print a test garment and check after curing fully, before printing in bulk.
We recommend embroidery for softshells. Screenprinting and heat transfers are ‘proceed at your own risk’.
This is because the fabric is particularly sensitive to heat, making them susceptible to overheating and dye migration.
That said, we have seen some fantastic print and transfer results on our softshells, without any dye migration.
A cold cure catalyst can enable curing without heat.
Alternatively, depending on your expertise and machinery, you may wish to try using heat and regular polyester ink.
Just be very careful of heat buildup – your gear will be hotter at the end of a run than the start.
And as the garments absorb heat, they can be hotter than the temperature gauge your dryer indicates.
Heat transfers with a blocking barrier layer may be another option.
Always test print a garment and check after curing fully, before printing in bulk.