Standardized Laboratory Methods for Evaluating Matte Print Coating Burnishing
Standard laboratory burnish evaluation uses controlled sled friction and 60-degree delta gloss measurements to quantify matte coating asperity degradation.
Dry Film Weight
Coating Mass
Gravimetric determinations of this type measure the dry solid residue of an aqueous or ultraviolet varnish remaining on a substrate after complete curing. The dry film weight represents the dry coat weight expressed in grams per square metre. It determines the barrier performance and the friction characteristics of the finished package.
Deposition Balance
Precision measurement requires weighing a known area of paperboard before and after the varnish application and drying process. An alternative method utilizes chemical extraction or thickness gauging to find the mass of the dried layer. If the weight is too low, the packaging is prone to scuffing and moisture intrusion.
If the weight is too high, the varnish may crack during subsequent folding or scoring operations. The correct weight ensures proper heat sealing and protects the printed graphics on the filling line.
Performance Standard
Achieving the targeted deposition relies on maintaining the correct varnish viscosity and anilox cell volume. Testing is performed regularly during the production run to ensure that the dry layer remains within specified tolerances. Highly absorbent paperboard requires more varnish to achieve the same dry mass because the liquid penetrates the fibers.
This measurement does not apply to wet inks before they go through the drying oven.