When printing onto a plastic such as vinyl, choosing the right printing ink and substrate combination is critical.

Aqueous inks are only acceptable for short-term indoor use and require specially coated vinyl substrates. UV-curable inks do not bind very well to uncoated vinyl and can scratch easily. Eco and mild-solvent inks bond lightly to many vinyl types, but every substrate needs testing before any purchasing decisions are made.

New latex inks work fairly well with vinyl, but require heat to make the inks bond which could be problematic with heat-sensitive plastics. True solvent inks bite deeply into vinyl materials and, despite the venting requirements associated with solvent inks, they are perhaps the best choice. Here are some tips for various ink options:

• Aqueous Inks - Water-based inks cannot print directly onto vinyl banners. The banner must be coated with an ink-receptive emulsion. The ink the bonds to this emulsion, but not directly to the banner. Coated banner media for aqueous inks is more expensive than uncoated media.
   
• UV-Cure Inks - UV-curable inks tend to sit on top of vinyl, and so use a form of adhesive to stick to the banner. This does not allow for a very positive bond between ink and substrate.
   
• Eco-Solvent Inks - These inks bond lightly to the surface of the vinyl banner material. Substrates should be checked for adhesion before shipping finished banners to clients.
   
• Low-Solvent Inks - More aggressive than eco-solvent, these inks perform fairly well with vinyl banner media.
   
• Latex Inks - These inks, offered by Hewlett-Packard, are pigmented, water-based inks use aqueous-dispersed polymer (“Latex”) technology. HP claims the inks deliver overall durability that outperforms eco-solvent ink, and is comparable to low-solvent ink.
   
• True Solvent Inks - These are, traditionally, the “king” of banner inks. The solvents in the ink bite deeply into the vinyl and provide a strong, durable bond. No further laminating or coating is needed. The downside is the toxicity of the inks which contain high levels of VOCs. Shops operating printers with true solvent inks must ventilate the work area.

If a longer-term product is desired, the banner can be coated with a liquid laminate. This can be applied with a special coating machine or the old-fashioned way with a spray gun or roller.