Why the extra coating on metal, glass, and acrylic

Maria

Hey folks,

I’ve had this question for a while. When a wall printer prints on metal, glass, or acrylic, why does it need that gel-like coating first? But when it prints on a regular wall, it doesn’t?

What’s that stuff called? What’s it even doing?

Appreciate any info.

Oscarlar

The gel-like coating on metal, glass, and acrylic surfaces is called an adhesive primer or a bonding agent. It helps improve the adhesion of the printed material to these non-porous surfaces. When printing on regular walls, the primer is usually not needed because the wall's surface is already porous and can absorb the ink effectively. Do you want to know more about the types of primers used for different materials?

Matteo

I agree that coating is one of the most important details when printing on materials such as metal, glass, tile, and acrylic.

UV coating is also called a UV treatment liquid or adhesion promoter. Its job is simple. It helps UV ink bond to surfaces that normally have poor ink adhesion.

Why Does UV Printing Need a Coating?

Some materials have very smooth or non-absorbent surfaces.

Glass, metal, ceramic tile, and some plastics are good examples. UV ink may look fine right after printing, but the image can scratch, peel, or come off more easily if the surface has not been treated correctly.

A coating creates a thin transition layer between the material and the ink.

This layer helps the cured ink hold onto the surface more strongly. In practical terms, it improves adhesion.

The important part is that there is no single coating that works perfectly on every material.

Different coating formulas are made for different surfaces.

Even two products that look almost identical may need different treatments because their chemical composition is different.

Plastic is a good example.

A plastic housing may be made from PVC, PC, nylon, ABS, or another material. Each one can react differently to the same coating.

That is why I would always confirm the exact material before choosing a coating.

Davina

Two Common Ways to Apply the Coating

There are two common coating methods used in UV printing.

One method is manual application.

The operator wipes or applies the coating directly onto the surface. The liquid is allowed to dry or evaporate according to the product instructions. Printing can begin after the surface is ready.

The other method is printable coating.

Some printer systems can jet a special coating through a printhead and cure it with UV light. This process is often called printed coating or jettable coating.

These two methods use different coating formulas.

A manual coating should not be placed into a printhead unless it is specifically designed for jetting. A printable coating should also be used according to the printer and ink system requirements.

Mixing the two types can cause poor adhesion or even create problems inside the ink system.

Mier

Le revêtement gelé utilisé sur les surfaces métalliques, de verre et d'acrylique s'appelle un primaire adhésif ou un agent de collage. Il améliore l'adhérence des matériaux imprimés à ces surfaces non poreuses. Sur les murs ordinaires, le revêtement n'est pas nécessaire car la surface du mur est déjà poreuse et peut absorber l'encre efficacement. Ce revêtement crée une couche fine de transition entre le matériau et l'encre, ce qui aide l'encre sèchée à se fixer plus solidement à la surface. Il est important de noter que pas de seul revêtement fonctionne parfaitement sur tous les matériaux. Des formules de revêtement différentes sont nécessaires pour différents matériaux.

Derek

The gel-like coating on metal, glass, and acrylic surfaces is called an adhesive primer or a bonding agent. It helps improve the adhesion of the printed material to these non-porous surfaces. On regular walls, this primer isn’t needed because the wall’s surface is already porous and can absorb the ink effectively. This coating creates a thin transition layer, helping the cured ink adhere more strongly to the surface. Different coating formulas are needed for different materials, so it’s important to use the right one for each surface to ensure good adhesion and durability.