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Common Plastisol Ink Additives
There are several common plastisol ink additives that may be used in a screen printing shop on a regular basis. These are plastisol additives that are mixed into existing pigmented plastisol inks to achieve different performance characteristics. Some are simply designed to extend the ink and others are made to make it less tacky. Most of the additives today will be balanced or curable. This means the additive is formulated to cure the same way the plastisol ink is. That way any amount can be added without causing curing problems. Some additives do require specific mixing ratios. The following is a brief explanation of some plastisol ink additives.
Extender Bases are used to increase the quantity of plastisol inks. When added to pigmented ink it causes the volume to increase. Most Extender Base additives are plastisol based and will not affect the cure process. Extender Bases will reduce the pigmented ink's opacity. Extender Bases can also be used as an under base in place of white for printing on polyester and cotton/polyester blends to minimize dye migration when a white under base is not the best solution.
Soft Hand Bases
Soft Hand Bases are clear plastisol base additives which reduce the ink's viscosity and make the ink penetrate into the fabric more so than extender bases. The final print has a softer feel to the touch especially when the ink mix is printed with a higher mesh count. Most Soft Hand Bases are plastisol based and will not affect the cure process. It will reduce the opacity of the ink it is added to. Soft Hand Bases are not good to use in situations where opacity is needed or with low-bleed inks being printed on polyester or cotton/polyester blend fabrics.
Halftone Bases are a transparent type plastisol base additives used in process, (CMYK), printing. It makes the ink print very well wet on wet. It also helps control dot smearing and dot gain because the ink penetrates further into the garment. It is not meant to reduce the viscosity. Most Halftone Bases are plastisol based and will not affect the cure process. It does however; reduce the opacity of any ink it is added to quite a bit.
Metallic Clear Bases
Metallic Clear Bases are transparent plastisol base additives with a thicker consistency than other bases. It is designed to be used with glitter flakes and metallic powders. The heavier body of the metallic base helps keep the coloring agent in suspension. Metallic Clear Bases are plastisol based and will not affect the cure process.
Reducers Or Viscosity Reducers
Plastisol Viscosity Reducers are used with plastisol ink and have special de-tacking agents that help reduce the amount of ink that adheres to the bottom of the screens when printing wet on wet. They also decrease opacity. Reducers are plastisol based and will not affect the cure process.
Flattening Agents such as suede additives can be added to reduce the high gloss of plastisol inks.
Sometimes you may want to increase the viscosity of a plastisol ink. This plastisol additive will cause the ink to thicken. Most are plastisol based and will not affect the cure process.
Flow Control Additives
When printing wet-on-wet; ink buildup on the back of the screens can degrade the sharpness of the printed image. Flow Control Additives can reduce this problem. It lowers ink viscosity and reduces the amount of ink that sticks to the back of the screen. Most are plastisol based and will not affect the cure process.
It is easier and less expensive to stock a transparent puff additive as opposed to buying puff ink in colors. Any plastisol ink in inventory can be quickly mixed into a puff ink with puff additive. These are plastisol based and will not affect the cure process.
Remember, it is always very important to read the technical data sheet, instructions and warnings from the vendor of your plastisol ink additives. Use only plastisol inks and additives formulated for your specific application. Make sure the additive you are using is compatible with your brand of plastisol ink. Mix all of your inks well and it is always a good idea to follow mixing instructions as closely as possible.