The Use of a Chrome Alum-Gelatin (Subbing) Solution as a General Adhesive for Paraffin Sections

The adhesion obtained from a chrome alum-gelatin solution has been found far superior to results given by widely used general adhesives (Haupt's gelatin and Mayer's egg albumen) for paraffin sections. The subbing solution, which consists of 5.0 gin gelatin and 0.5 gm chrome alum per liter of water, is easier to apply and gives more consistent results. Sections affixed to subbed slides are resistant to removal by acids and bases: 1.0 and 0.1 N HCl or H2SO4, 1 M H3PO4, 5% oxalic and trichloroacetic acids, 1% and 10% lactic acid, 1.0 and 0.1 N NaOH or NH4OH, and other fluids and solutions such as organic solvents, water, hypochlorite, KMnO4 and thiosulfate. The applied adhesive is virtually unstained by many stains, including hematoxylin, eosin, fast green, safranin, PAS, Sudan IV and Mallory's triple stain. The only treatment yet found to detach affixed section in less than 6 hr is immersion in 5% trichloroacetic acid for 15 min at 100 C. The concentration of gelatin and chrome alum in the solution recommended is much lower than in previously described adhesives, but this does not seem to lessen its ability to affix the sections. If the concentrations of gelatin and chrome alum are decreased from those described, adhesive qualities are also decreased. An increase in the concentration of the ingredients causes the adhesive to become stained. The described solution therefore gives optimum adhesion and “resistance” to staining.