CEMENTS FOR MENDING 507 



Coloring cement work. 



For gray or black, lampblack may be employed. 

 For yellow or buff, yellow ocher. 

 For red, Venetian red. 

 For blue, ultramarine. 

 For brown, umber. 



Mending Cements 

 Cements for iron. 



1. (Slow setting.) Sal ammoniac, 2 ounces ; sulfur, 1 ounce ; clean 

 iron borings or filings reduced to powder, 12 pounds ; water enough 

 to form a thin paste. Excellent for making a rust joint. If a quick- 

 setting joint is desired, use half as much sal ammoniac as sulfur, and 

 half as much iron borings as above ; not so good as above 



2. Sal ammoniac, 2 ounces ; iron-filings, 8 pounds ; sufficient water. 



3. One or two parts of sal ammoniac to 100 of iron-filings. When the 

 work is required to set quickly, increase the sal ammoniac slightly and 

 add a small amount of sulfur. 



4. Iron-filings, 4 pounds ; pipe-clay, 2 pounds ; powdered pot- 

 sherds, 11 pounds ; make into a paste with moderately strong brine. 



5. Equal parts of red and white lead, mixed into a paste with boiled 

 linseed oil. Used for making metallic joints of all kinds. 



6. To four or five parts of clay, thoroughly dried and pulverized, 

 add 2 parts of iron-filings, free from oxide, 1 part of peroxide of man- 

 ganese, I of sea salt, and h of borax ; mix well, and reduce to a thick 

 paste with water. Use immediately. Expose to warmth, gradually 

 increasing almost to white heat. 



7. Sifted coal ashes, 2 parts, and common salt, 1 part. Add water 

 enough to make a paste, and apply at once. This is also good for 

 stoves and boilers, as it stands heat. 



Boiler cements. 



8. Chalk, 60 parts; lime and salt, of each, 20 parts ; sharp sand, 

 10 parts ; blue or red clay and clean iron-filings, of each, 5 parts. 

 Grind together and calcine or heat. 



9. Powdered clay, 6 pounds ; iron-filings, 1 pound. Make into 

 a paste with linseed oil. 



