170 ENGINEERING ON THE FARM 



Cement paint. Ordinary oil paints are not satisfactory 

 when applied to a concrete surface. The excess of alkali 

 in the cement must be neutralized in some measure. The 

 general practice is to use a special cement paint. It is char- 

 acterized by the addition of zinc sulphate or an equivalent. 

 If the ordinary paint is to be used, it is necessary first to 

 wash the surface with a solution of zinc sulphate, which 

 should be followed by a clear water washing and allowed 

 to dry thoroughly. The market offers solutions for cement 

 floor treatment which are, in fact, only hardeners. They 

 are very effective and comparatively cheap, since a large 

 percentage of the hardener is water. 



Creosote. This protective solution is made of creosote 

 oil with the addition of a pigment to give it color. Creo- 

 sote is the result of tar distillation. It is highly preserva- 

 tive and, being thin, penetrates a surface such as wood or 

 fiber. 



Stains. Stains are of four varieties: oil, water, spirit, 

 and acid. A stain is not intended to be a covering. It is 

 applied to change the appearance of a surface. Oil stains 

 usually contain very little of the vehicle oils ; they are very 

 largely the solvent and drier oils, with the addition of 

 sufficient pigment to give the desired tone. Water stains 

 are similar in make-up and application, except that water 

 is the solvent and carrier. The water stains have the 

 unfortunate peculiarity of roughening or raising the grain 

 of the wood, making it necessary again to rub the surface 

 in order that it may be finished smooth. Spirit stains are 

 practically the same as water stains, except that alcohol 

 is used instead of water. They are a little more penetrat- 

 ing and give better results on very hard wood. Acid stains 

 are more penetrating than any of the others, since their 

 solvent and carrier is acid. Little, if any, pigment is neces- 

 sary with an acid stain. The acid, itself, attacks and 

 colors the surface of the wood. It is usually necessary to 

 add a neutralizing agent, such as ammonia, in order that 



