SCREEN PRINTING

Knowing your substrates

Polyester fabrics can migrate so it’s a good practice to always test your garments prior to running production. Print the fabric with the recom?mended inks and print processes. After printing place the fabric or gar?ment in a box in a warm area and let it sit for a few days to allow it to run it’s migration course. Migration can happen immediately or can take up to a week to fully migrate. If it migrates than you will know what you need to add to your print to be successful. Another way to test your fabric is to do a migration test. Your ink provider should have a method to determine how much the dye will migrate. Heathers and Triblend are super soft lightweight garments and using a lot of heavy inks is not very appealing so it is always best to discuss graphic options that work with you substrates to give the best outcome when decorating synthetics.

Dye Blocker Inks

There are a few different ink platforms to choose from. Low Bleed, High Poly and Low Cure inks.

• Low Bleed These inks are great for 50/50 blends where the fabric has a low synthetic content
• High Poly These inks are for 100% polyester fabrics to high poly content fabrics. Their viscosity is thicker and super opaque.
• Carbon base Grey/BlackThis ink is used as a underbase to absorb the dye when it gases and reduces/blocks the dye from working thru to the surface of the ink.
• Low Cure These inks a have a low blocking agent but they cure at 250-280 degrees and are great for Heathers, Triblends and substrates that you need detail and you need a great hand. Since the fabric is Low Cure you reduce the heat so no more scotching those sensitive garments and also you reduce energy which saves you money.

Tips & Techniques

• Mesh Count: Using a 110-160 mesh will allow you the best coverage and opacity for your base screens. Your Top inks can be 160-230mesh. I would have you White Overprint mesh to be 110-160.
• Viscosity: make sure you stir you ink prior to production to reduce the viscosity to help push the ink thru mesh and give you a better print sur?face.
• Squeegee Pressure: Using the at least amount of pressure is key. Keep?ing the ink on the surface of the fabric will help with opacity, hand and migration. If the fibers work up thru the ink it will increase the chance of dye-migration. Also if you have to much pressure it will push the ink thru the fabric and this is undesirable feeling touch the skin.
• Tapping/Smoothing Irons: Poly inks are thick and when printing on per?formance, Heathers and Triblend fabrics hand is just as important as reducing migration so being able to smooth your ink surface will improve the quality of the prints as well as the feel of the print. In your first station have a tapping/smoothing screen to lay-down any fibers. Print your base screen and flash but instead of a cool-down station add another tap?ping/smoothing screen to smooth out the ink. Then you can print your top colors inks. It is recommended to use two white screens.
• Screen Tension: You want to make sure to keep your ink on top of the fabric. The best way to do this is having the proper tension in your screens. If your screens are tight and you use a thin thread diameter the mesh openings will allow better lay-down. You will not need a lot of pressure, your registration will be cleaner and tighter. You can achieve a smoother surface with less mesh texture in your ink. If you have poor tension in your screens you will have registration issues, you will be force to apply more pressure to get the ink thru the screens. Which will drive the ink thru the fabric and allow fibers to work themselves up on top of the ink and cause more dye-migration.
• Flashing and Curing: Migration occurs around 270° degrees Fahrenheit/ 97.2° degrees Celsius. This is the most important step when printing on polys. Make sure not to over flash or over cure your garments. Use inks that have a quick flash point. Flashing should only be a few seconds and keep temperatures below 200° degrees Fahrenheit. Reduce the number of flashes in your design. If you don’t have to flash don’t. Use inks you can cure at a lower temperature like 250?- 270° degrees Fahrenheit. Slow belt speed to assure the ink is cured. Do not exceed the curing temps.
• No Stacking: If you can use fans and long cooling stations on your dryers this will help cool down the garments faster. If your garments are still warm do not stack them until they are completely cool. Pressure and heat can accelerate any migration.

If you follow these few simple steps you will have a better chance at being successful when screen printing blended and 100% Polyester garments. Most ink vendors will offer their expert advice and will travel to your shop to help with all your printing issues and needs.