Example: Staining of sample due to gaps between resin and
sample, Mag. 20 X.

Staining is a discoloration of the sample surface, tipically because of contact with a foreign body. Staining is often seen after claning or etching samples. There is a gap between sample and resin, water, alcohol or etchant can bleed out of the gap during drying or even on the microscope. Areas on the sample surface can be discolored, and make the examination difficult or even impossible.

Reference: Metalog Guide, page 94-95, Struers A/S, 2610 Rodovre, Dennmark.
Note: Image and text by courtesy of Struers A/S company.