- Kieth Stevens
One of the most asked question here at International Coatings is about Curing Ink. More specifically, how to cure plastisol inks correctly. Once again, we are tapping one of our print experts for more info on this topic, so here is Kieth Stevens, International Coatings’ Western Regional Sales Manager:
“I usually compare plastisol ink to a cake or cookie batter. Like the cake batter, there are several components that make up plastisol ink: There is the “flour” (resin), the “water” (plasticiser), “eggs” (special additives for stretch or adhesion etc.), and “flavorings” (color pigments). You get the idea.
When it comes down to it, plastisol ink is really not that complicated. But when it comes down to curing thick ink layers (high density or puff prints for example) or thin layers (i.e. 4-color process prints) the number one thing to remember is that for plastisol to fully cure, the whole ink film (its thickness) - from top to bottom, including the center - must reach a temperature of 320 degrees F (160º C).
So, let’s go back to the cookie and cake batter illustration: Both may require the same temperature to fully cook, but the cake requires more time. In another example, if you raise the temperature of the oven hoping for the cake to bake in the same amount of time as a cookie, you would run the risk of burning the top and bottom of the cake while the center will still be undercooked.
Similarly, if a heavier deposit of ink is run through the dryer too fast or is only flash-cured, the top of the ink may feel dry to the touch, but the center of the ink may not be fully cured and the ink may crack or completely wash off. More time in the oven is always your best friend.
To test whether your ink is fully cured, try stretching the print. If it cracks, it very well could be that it is under-cured. I hope that this illustration helps to better understand the process of ink curing. Your local International Coatings distributor can also help you if you have further questions.”
