A Practical treatise on artificial crown- and bridge-work / by George Evans.

  • George Evans
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: A Practical treatise on artificial crown- and bridge-work / by George Evans. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    Fig. 628. CHAPTER IV. SOLDERING. Investments for soldering, and models on which the soldering is to be done for bridge-work, are made of calcined mar- ble-dust and plaster, in the proportion of equal parts for models, and one part of plaster to two of marble-dust for investing; or one part plaster, one cal- cined marble-dust, and one of common white sand. If the investment is large, an iron wire should be passed through or around it in the material. Sulphate of potassium, used in place of common salt, but in smaller quantity, will cause the mixture to set quickly and hard. Soldering.—In soldering crown-and bridge-work or sections of it containing porcelain fronts, the investment should be first uniformly and thoroughly heated, and the heat maintained during the process of soldering. This is espe- cially necessary in the final soldering of gold crowns with porcelain fronts, as the solder is thereby flowed into the interstices between the porcelain and the caps, and gives continuity of struc- ture to the crown. A large piece of charcoal, concave on the side to be used, and the other side invested with a thin covering of plaster, furnishes a good soldering support, as it retains the heat. A hand gas blow-pipe, operated] by a
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