VARNISHES 159 
Formaldehyde 100 ccm 770 min. 
Glycerine 100 ccm 770 min. 
Denatured alcohol (meth. 
spirit ) 300 ccm 434 oz. 
Water to 1000 ccm 16 oz. 
The carbonate should be dissolved in the glycerine, and the 
water and other ingredients added... This solution is rather 
slower than the hydrofluoric acid; it can be used in a dish 
and allowed to act for 20 to 30 minutes. When the film 
proves to be loosened, pour off the solution, replace with a 
mixture of 4 parts of alcohol and 6 parts water, and leave 
for 5 to 10 minutes; then lift the plate out, drain, and strip 
the film as outlined above. 
