Glycerol Gelatin Mountants

Glycerol (glycerine) and gelatin mixtures are popular water miscible mounting media. They must be applied warm so that the gelatin has been melted, then allowed to cool, when the gelatin will harden again. Like many non-resinous mountants ringing the coverslip with a cement is desirable if the slides are to have a degree of permanence as the mountant will otherwise dry back. Due to their syrupy consistency, these mixtures should not be shaken when melting for use as that can cause bubbles in the medium and their syrupy consistency causes the bubbles to dissipate relatively slowly. They should be melted without agitation and with a fairly mild degree of heat, about 37°C. Glycerol gelatin media have a refractive index lower than that of glass, so the finished preparation does not have the clarity of a resin mounted slide, although adequate for a lipid stain.

The gelatin used for these media should be the purest available, without any cloudiness. Commercially prepared laboratory grade gelatin is usually suitable.

Glycerogel and glychrogel are both quite popular. Both are suitable for coverslipping lipid stains, and are recommended.

Glycerogel (Carleton & Leach)  
 • Dissolve the gelatin in warm water.
 • Add warmed glycerol and phenol.
 • Refrigerate, but warm gently to melt for use.
Glychrogel (Zwemer)  
Chrome alum
 • Dissolve gelatin in 50 mL warm water.
 • Dissolve chrome alum in 30 mL warm water.
 • Warm glycerol and add to gelatin.
 • Add chrome alum, filter and add a little camphor.
 • Refrigerate, but warm gently to melt for use.

There are numerous formulas for glycerine jelly mountants. In the list below all numbers refer to grams if a solid and mL if a fluid. "Water" refers to distilled water. "Glycerol" refers to 99.5% glycerol. Most formulas specify a volume of water, a few do not. Dry gelatin usually needs to be "bloomed" before use. This is done by soaking in water until no more water is absorbed, and takes a few hours. Where the formula specifies a volume of water, use some of this for blooming. If the formula does not specify a volume of water, bloom the gelatin in water, drain well, then melt in a paraffin oven before combining with the other (warmed) ingredients.

It is recommended that small amounts be aliquoted into small jars or test tubes and refrigerated. For use, these media require to be melted. This should be done gently and without agitation in order to ensure bubbles do not form.

Variant Water Gelatin Glycerol Other
Baker 65 5 35 Cresol 0.25
Brandt 40 60 Phenol 0.5
Dean 30 15 55
Fischer 100 10 17 Sodium borate 2.0
Forbes 40 9 50 Phenol 0.6
Guyer 50 8 50 Phenol 0.25
Kaiser 40 7 50 Phenol 1.0
Kisser 60 16 50 Phenol 1.0
Moreau 42 7 50 Phenol 1.0
Norstedt 42 14 56
Roskin 42 7 50 Phenol 0.5
Roudenowski 20 50
Schact 36 12 48
Wood 100 20 10 Strong formalin 1.0
Yetwin 83 5 17 Chrome alum 0.3, Phenol 0.3


Gray, Peter. (1954)
The Microtomist's Formulary and Guide. pp. 633.
Originally published by:– The Blakiston Co.
Republished by:– Robert E. Krieger Publishing Co.

Carleton, H M, and Leach, E H, (1938)
Histological Technique, 2nd ed.
Oxford University Press, London, England

Gatenby, J. B. and Beams, H. W., (1950)
The Microtomist's Vade-Mecum Ed. 11. pp. 210
J. & A Churchill Ltd., London, UK.


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