Enamel making

The addition of stannous or sodium fluoride is effective in the prevention of dental cavities, because the fluoride ion actually becomes part of the tooth enamel, making the enamel stronger and more resistant to the attack of acids. 

There has been considerable controversy over the addition of fluoride (t5q)ically in the form of NaE) to drinking water. Eluoridation strengthens tooth enamel, making it more resistant to decay. Search the web to find typical concentrations of fluoride in water that are used for fluoridation. Convert the ppm (or ppb) concentration you find to molarity. 

We call earthenware the ceramic products made up of a porous shard covered with a glaze. This enamel makes it possible to mask the appearance of the shard and to remedy the high permeability due to the existence of an open porosity ranging between 5 and 20%. Although present in the form of objects of imagination and crockery, earthenwares are especially nsed as wall tiles. 

Selenium is used in Xerography for reproducing and copying documents, letters, etc. It is used by the glass industry to decolorize glass and to make ruby-colored glasses and enamels. It is also used as a photographic toner, and as an additive to stainless steel. 

Activators. Activators are often added to removers to make them more efficient. Acids such as phenol [108-95-2] phosphoric acid [7664-38-2] acetic acid [64-19-7] formic acid [64-18-6]., and citric acid [5949-29-1] are used to increase the cutting abiHty on epoxide-type paints and other modem finishes. Strongly alkaline activators are effective on enamel andlatex paints. Other activators include ammonia [7664-41-7] monoethyl amine [75-04-7], and /V-phenyIdiethan ol amines. Acid and base activators shorten the shelf life of some removers. 

Barium nitrate is prepared by reaction of BaCO and nitric acid, filtration and evaporative crystallization, or by dissolving sodium nitrate in a saturated solution of barium chloride, with subsequent precipitation of barium nitrate. The precipitate is centrifuged, washed, and dried. Barium nitrate is used in pyrotechnic green flares, tracer buUets, primers, and in detonators. These make use of its property of easy decomposition as well as its characteristic green flame. A small amount is used as a source of barium oxide in enamels. 

The preparation of the enamel slip includes ball milling the frit and raw materials to the appropriate consistency. Frit is the glassy raw material that makes up the backbone of porcelain enameling. Most frit is manufactured outside the operation but some plants do include captive operations. Other raw materials, such as clay and gums, are mixed into the frit by the ball mill that then releases this mixture to the coating operation.3 6... 

The flask should be immersed as far as possible in the oil (to within about 100 mm. of the top of the flask). This is important. A i-gal. enamel-ware coffee-pot makes an excellent oil bath. An ordinary soldered vessel will not stand the temperature. 

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