Most substrates need a bit of help to achieve excellent adhesion. For this reason, primers are a vital addition to the printing process. UV flatbed printers are a staple for anyone in the printing industry. Their appeal comes the ability to print onto pretty much any substrate in full color. Primers help make this versatility possible.
A UV ink primer is a substance applied as a preparatory coat to an object, usually as the first step in the printing process. Sometimes, pretreatment comes before priming, when needed. Popular pretreatment methods include flame, Pyrosil®, and plasma treatments. The main function of a UV ink primer is to promote adhesion through strengthening the physical bond between the UV ink and substrate.
The best way to ensure full adhesion is to cure the substrate with primers or by flame treatment prior to printing. Flame treatment is ideal for substrates that require a manipulation of surface tension, such as glass and polypropylene. An oxidized flame (should be blue in color) increases the movement of molecules on the surface of the substrate, thereby improving adhesion between the ink and substrate. The general rule of thumb when it comes to UV ink primers is that if you can get away with not using one, then don’t. Primers should only be used as needed. Skipping this step will save you time and money, but depending on your application, could result in a lower quality design.
Superior adhesion depends on multiple factors such as the dyne levels of the ink and substrate, surface energy, coatings, and other bonding factors. Generally, the surface tension of the UV ink should be about 10 dynes less than the surface energy of the substrate. Since the range of 25-35 dyne is standard for UV inks on the market, we can expect a high-quality print to occur from printing on a product that has a surface energy between 35-45 dyne.
UV ink primers can either be sprayed on or manually wiped on a substrate. For primers that cannot be sprayed on, the primer should be applied to a lint free towel and wiped on the object. Due to the viscosity of some primers, the concoction doesn’t fit through spray guns or is flammable due to a low flash point (the point at which a substance combusts). Other pretreatments and primers are part of an automated machine process.
Inkcups provides many UV ink primer solutions for a variety of substances. MagiCoat®, the pretreatment system for glass, is a breakthrough water-based inkjet ink primer that optimizes adhesion on glassware and other substrates. This system features 8 rotating stations, 3 flaming stations, and a fine mist spraying system. The rotating stations include a vacuum to keep products firmly in place during pre-treatment. Next, the products are ready for the flaming stations and 6 flaming heads work to uniformly pre-treat the items. Flame treating eliminates any debris or other coatings already on the substrate that may inhibit adhesion. The fine mist spraying system ensures that each item gets evenly coated with water based MagiCoat® primer as part of the post-flame treatment. After the pre-treatment process, drinkware items have seen up to 600 industrial washes without image degradation. *
The revolutionary AutoFlame 360 Flame Treatment Machine automates the flame pretreatment process. The machine features 8 rotating platens with vacuums to secure the objects. Once the product has been evenly treated with the optimal amount of flame, a built-in hydraulic system will lightly tap the finished product into a box. This easy load/unload system makes pretreatment part of the in-line printing process and helps to maintain a steady workflow.
Some substrates have specific properties which inhibit full ink adhesion. These substrates require adhesion promoters specially designed for each substrate. Inkcups offers 8 varieties of inkjet primers to ensure all substrates are covered, because we know that every part is unique. Inkcups offers inkjet primers for glass, metal, plastic, tile, and more. Once your substrates are pretreated, continue to print as normal and expect better adhesion, increased durability, and improved abrasion resistance.
When it comes to decorating various substrates, a pretreatment and/or primer may be required for an overall high-quality print. Depending on the substrate and application, there is a primer that is right for you. For customers looking for a primer, we encourage them to read through the technical data which is available for all of our products. Free adhesion testing is available upon request in order to determine the best primer for your product. Our expert ink technicians at Inkcups have experience working with a multitude of different substrates over many years. Our goal is to improve adhesion and increase abrasion resistance to ultimately create vibrant, durable products for satisfied customers.
*Glass MUST be flame-treated prior to use of MagiCoat. Wash testing could be more (or less) depending on type of glassware used, detergent and temperature of wash.