MPgrading has contracted two seperate forensic paper testing laboratories to definitively determine the age of posters suspected of being reproductions. Each forensic lab has a variety of tests they can preform to determine the pH, species present (types of wood used in the pulp production), coatings, additives and manufacturing process to identify the age of the paper.
These labs perform ISO, ASTM and TAPPI method for all paper and paperboard tests, including: physical, optical and thermal coating property, and printability testing.
One of the more common tests to determine the era in which the paper was manufactured is the pH test. This test can determine if the paper was manufactured in the late 1980’s when Paper Manufacturers in this country changed from an acid based process to an alkaline besed process to decrease the degradation (yellowing and aging) of the paper over time.
Another common test is the Graff’s “C” stain, which can determine the species of tree that the paper is made from. Several reproductions were produced in Canada and Japan which typically used differenty species of trees in their pulp production.
Graff's "C" stain Graff's "C" stain w/yellowing
Calcium Carbonite Bubles Starch Extracted