Carborundum grit

Particles of grit such as carborundum, when added to an expl, can artifically create hot spots (see Vol 7 H170-L to H175-R) when the expl is suddenly compressed by impact as in an impact sensy device. Only grit particles of mp higher than that of the expl can initiate higher temp hot spots and thus increase the sensitivity of the expl... 

Under the term spots may be understood small, hard particles of material, such as sand, powdered glass, carborundum, etc, incorporated in an explosive either on purpose or present as impurities. Such particles are known as grit. The term spots may also be applied to small bubbles of air or other gases entrapped in cast explosives or incorporated on purpose in other expls, such as by rolling cartridges of gelatinous Dynamites. The reason why these spots are called hot spots is explained below... 

Grinding should be done with 120-grit Carborundum and plenty of available water. Adding a little dishwater soap will help lubricate of the pieces as they are ground. 

Glass and quartz Acetone, detergent 1. Abrasion grit blast with carborundum and water slurry, For general-purpose bonding. Drying process... 

Ceramics and porcelain Acetone 1. Abrasion grit blast with carborundum and water slurry and solvent-degrease. 2. Solvent-degrease or wash in warm aqueous detergent, rinse, and dry. 3. Immerse for 15 min at 20°C in Sodium dichromate 7 Water 7 Sulfuric acid (96%) 400 Rinse in water and distilled water. Oven-dry at 66°C. ... 

For ferrous metals there is no reason why shot blasting should not be used but, for other metals, grit blasting with alumina or carborundum is preferable. For small scale work, although a surface of a different type is produced, rubbing with emery, carborundum or garnet paper is acceptable. All these methods remove metal and can, in fact, remove a few thou from the surface. For accurately machined parts, therefore. 

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