Our Solvent Resistant Pens feature ultra-permanent ink that resists solvents such as xylene, alcohol, acetone and formalin. Ideal for histology and cytology. Markings will not run on embedded cassettes, frosted or painted slides or labware, even after repeated washes and solution treatments. Markings can be removed with acetic acid, ethanol/xylene mixture or paraffin. Testing is advised before use. Results may vary based on surface.