Inks made from the Selectasine Binders and Pigments provide excellent wash fastness on fabric. It is advisable to allow the ink to dry for at least 24 hours before fixing them with heat.
When the print is dry, the screen inks will require fixing (fixing is also known as curing) before it can be washed or dry cleaned.
This completes a chemical process that would have occurred naturally over a period of time, where the polymer molecules in the binder “cross-link” trapping the pigments in the fibres of the material. If adequate heat is applied, then this reaction will speed up and complete.
Ironing at 165°C (330°F) for 4-5 minutes on the reverse of the printed fabric will set the print so that the ink is wash fast. Adding Selectasine Crosslinker at 20g per kg to the ink will decrease the setting time to as little as one minute.
The success of this method is determined by the following:
- Inadequate fixing – not enough heat is applied over a long enough period
- The binder is overloaded with pigment. Surplus colour will come out in a wash causing discolouration of the water and staining
- Fibre content or finish on fabrics – synthetics such as lycra and polyester and highly starched or treated fabrics will repel the polymer molecules. Cotton and natural fabrics give the best results.
- The fabric is not ‘Prepared for Dyeing’ (PFD) or requires scouring to remove any grease, oil or starch. Run a few droplets of cold water onto the fabric. If they soak in quickly, no scour is necessary. To remove starches, size and oils, add 5mls of Synthrapol (a non-ionic detergent) along with 2-3 litres of water for each 100g of material. Stir gently over a 15 min period, and then rinse thoroughly in warm water. It is possible to use household detergent, but the alkaline residue may affect the final colour or wash fastness.
The Selectasine Screen printing system has developed over many years and is used extensively for printing. We are often asked about the types of surfaces on which it can be printed. Most substrates can be printed onto using this system, but not every substrate will be suited to this medium and the print will not necessarily be permanent. We would always recommend a trial print and a test wash before selling any product on the market.