Choosing the Correct Pad Printing Ink
by Jessica Makrinos
There are several things to consider before purchasing ink for a pad printing project.
Ink that is ready for print has four properties, including
- Pigment: supplied in powder form, this gives the ink its color and opacity
- Solvent: enables the resin and pigment mixture to be transferred to the substrate during printing
- Resin: forms the finished ink
- Additives: improve flexibility, flow and pigment stability
Understanding all of that, here are a few things to consider when choosing the correct ink for a particular substrate.
1. Determine what the substrate is made of
One factor, if not the most important factor, is to understand what the substrate is made out of. Different inks adhere to different substrates, so skipping this step and ordering an ink without doing research probably will result in a failed print. Luckily, most companies will ask customers right away what they are trying to print on or request a sample of the substrate to do adhesion testing.
2. Type of abrasion or chemical resistance
If certain chemicals will be used to clean the substrate, it is important to choose an ink that can withstand such abrasion. For example, if the substrate is going to receive cleaning with alcohol, choose an ink that can stick without peeling or discoloring. Additionally, if an item can be placed in a dishwasher, you also will need to take this into consideration. Dishwashers are the harshest on prints because of the combination of detergent, alkali and hot water.
3. Gloss level
Another component of choosing the right ink is determining if it should have a glossy or a matte look.
4. Drying Speed
Drying speed, or evaporation rate, is only a factor if the products will be packaged and shipped immediately, or if the materials need to be stacked.
5. Specialized Applications: Silicone
Ink used for printing on silicone is tricky. Not only does it have to adhere well to the substrate, it also must pass a flexibility test – being able to be stretched and bent without cracking. These inks usually are cured to ensure the best durability.
6. Medical Grade
For applications where the ink may be ingested, it is important to use an ink that does not contain any heavy metals, among other restrictions. All toxicity levels are strictly controlled.