This steel plate engraving and mezzotint illustrates the hazard of utilizing acidic backing materials when housing artwork. In this case, wooden slats were originally utilized. Looking closely, one can observe the acidic staining patterns in the sheet that follow the edges of the slats and the knots in the wood.
After the inks on the surface were tested for stability, the staining was reversed by cleaning and bathing the artwork and giving the artwork a thorough surface cleaning. The artwork was then strengthened with sizing and dried under weight for a period of days, gradually wicking out all the remaining moisture in the paper.