Scratch-off ink: absolute opacity, clean release
Scratch-off ink sits on a single contradiction. Opacity must be absolute — no light transmission, no reading from the reverse side, no seeing through under strong light. Release must be clean — no residue, no tearing the base paper, no pulling the print underneath away with it. Most field complaints — will not scratch open, will not scratch clean, dusting, smeared text — come not from the ink itself but from a mismatch between the base coat / release layer and the thickness of the scratch layer.
Water-based and oil-based routes each have their place. Paper scratch cards typically use a screen-printed water-based system: lower cost, a crisper scratch feel, clean removal. Non-absorbent substrates, or cases needing stronger opacity and secrecy, call for an oil-based system with better coverage and weatherability. Opacity depends not only on formulation but on coat weight and whether a release layer is present — thin coats save cost but transmit light, thick coats hide well but may not scratch clean. That balance is settled at the proofing stage.
We recommend proofing together with the base print, because compatibility between the scratch layer and the underlying ink determines the result: an incompletely dried base, or a reaction with the scratch layer, produces blocking, smeared text and incomplete removal. Scratch feel (brittle or tough), opacity and colour are all adjustable, and complete proofs including base print and scratch layer are available for press trials before mass production.
Frequently Asked Questions
Selection, detection, printing and ordering — answered.
The scratch layer transmits light and the code can be read from the back. What causes this?
Three common causes: coat weight too low, insufficiently opaque formulation, or a missing release layer. Remedies are to increase coat weight, switch to a higher-opacity oil-based system, or add a base release layer. Which route applies depends on substrate and cost constraints — proofing should test both front transmission and show-through from the reverse.
What causes incomplete removal, dusting and smeared text?
Usually compatibility between the scratch layer and the base ink: printing over an incompletely dried base, or a reaction between layers causing blocking. It can also be an over-thick scratch layer or a scratch feel (brittle versus tough) mismatched to how users actually scratch. Proof together with the base print so drying conditions and interlayer compatibility are fixed as a system rather than tuning the scratch layer alone.
Water-based or oil-based scratch-off ink?
Paper scratch cards usually use a screen-printed water-based system — lower cost, crisper feel, clean removal. Non-absorbent substrates, or cases needing stronger opacity and secrecy, call for oil-based. Where light transmission must be tightly controlled, oil-based is generally the safer choice, with drying and environmental requirements factored in.
Can you provide proofs including the base print?
Yes. Complete proofs with base print and scratch layer are available so scratch feel and opacity can be validated on press before mass production. Scratch feel, opacity and colour are adjustable — please describe the scratching method (finger, coin, nail) and the required secrecy level.