CHAPTER VI. 



THE TECHNICS OF CASEIN PAINTING. 



CASEIN painting is based on the principle that casein pos- 

 sesses the property of forming extremely resistant and 

 permanent compounds, both with the pigment and also 

 with the substratum. The subject is, therefore, divisible 

 into several sections, viz. : 



1. Preparation of the ground. 



2. Preparation of the binding medium. 



3. Preparation and application of the casein paint. 



Although from its nature casein painting is no more diffi- 

 cult than any other branch of the art, certain precautionary 

 regulations must nevertheless be observed in the preparation 

 of the ground and surface to be painted on. In the first 

 place, surfaces of solid and granular lime- or cement-plaster ; 

 surfaces already coated with a layer of oil paint, and sur- 

 faces consisting of ordinary building stone, or ornaments of 

 clay, wood, sheet metal, etc., must be thoroughly cleaned 

 before painting is begun. If casein paint is to be applied 

 to rough lime plaster the latter must be brushed over with 

 diluted milk which has been carefully skimmed and mixed 

 with the right quantity of water. Defective places in the 

 plaster of house fronts must be patched up with mortar, or 

 preferably with a mass composed of 1 part of patent lime 

 and 3 to 4 parts of pure sand. Patent lime is made by 



allowing solutions of tin and zinc chloride to act on lime, 



(66) 



