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The user is experiencing issues with contrast when laser engraving brown, uncoated cardboard. The contrast comes mainly from soot, which is easily removed during cleaning. They need a production-viable solution where soot stays more on the surface, allowing dry cleaning without washing out the engraving, without a sticky or glossy finish.
Hi everyone, I’m currently laser-engraving brown, uncoated cardboard using a 50 W CO₂ laser (Omtech Polar). Raster engraving, unidirectional fill, very small text. The problem is that the contrast comes mainly from soot, which penetrates into the open-pore cardboard. When I clean the surface (eraser, dry-cleaning sponge), the engraving quickly loses contrast because you inevitably touch the engraved areas. Masking / tape / shields are not practical due to the small typography and production volume. Goal: A production-viable solution where soot stays more on the surface, allowing dry cleaning of the background without washing out the engraving. No sticky, glossy, or plastic-looking finish. I’m currently evaluating the following options and would appreciate real-world experience: * Surface sizing (PVA, starch, methyl cellulose) → Effective concentrations? Laser-friendly? * Very thin water-based acrylic dispersion (not varnish, not PU), possibly with a small amount of kaolin or CaCO₃ → Which binders dry non-tacky? How does it behave under a CO₂ laser? * Pigmented coatings (clay / CaCO₃ + binder) as a DIY approximation of coated board → Any practical experience? * Dry cleaning methods (Wishab/Akapad soft sponge, antistatic brushes) → Techniques to clean only the surface without affecting engraved areas? * Post-processing contrast enhancement (graphite / charcoal) → Stable results or surface contamination issues? I’m not looking for hobby experiments, but reproducible solutions suitable for small-series production. Thanks in advance for any insights.