UV flatbed printers are extremely popular machines today, as they make it easy and cost-effective for users to print on just about anything. There are different types of UV inks available for a variety of applications, along with a wide selection of rigid media that can be printed on directly using these advanced, incredibly versatile devices.
While UV flatbeds are capable of printing on virtually any substrate or object, there's always a possibility that the UV inks used may crack or peel off over time. Adhesion is dependent upon several variables, including the quality of the UV device and inks being used and the type of material those inks will be printed on. Keep in mind that UV inks sit on top of your media, unlike eco-solvent inks that penetrate into the substrates on which they are printed (i.e., rolls of car wrap vinyl).
Included in the photos shown below is one example of a “cross-hatch” adhesion testing procedure. This tester kit basically scratches lines through the ink down to the substrate in a cross pattern.
Note: This type of cross-hatch pattern can also be cut using a box knife.
The best possible result from this kind of testing is having the UV ink peel off only where your cut patterns were made. If you notice that a lot of UV ink is peeling away, you should consider using an adhesion promoter (primer), which is usually hand-applied or sprayed on prior to printing. Some devices, however, such as several of Roland DG's UV printer models, have an “onboard” adhesion promoter option in their respective inksets.
If your UV printer doesn't have an onboard primer option, here are two companies that offer adhesive promoters for different media types:
- SEM Products (product - XXX 77724)
- Marabu
Note: Before printing, make sure you clean the surface of your media with isopropyl alcohol or a similar solution.
Firmly apply a piece of packing tape over the pattern, then firmly and quickly pull off the tape. This result is an example of perfect adhesion – notice how the tape only took off the UV ink between the cross-hatch pattern.
This media has a very hard surface that is almost like glass. We performed the same cross-hatch pattern as we did on the Sintra-like media above.
The test shown above failed. When you encounter this type of result, an adhesion promoter may be needed to improve ink bonding.
