platinum foil

platinum foil,

a very thin sheet of pure platinum that has a high fusing point, making it an ideal matrix in various soldering procedures for fabricating orthodontic appliances and dentures. It is also commonly used as the internal form of porcelain dental restorations during fabrication.

---

foil,

n a very thin, flexible sheet of metal, usually gold, platinum, or tin.

foil, adhesive,

n a tin foil that is covered on one side with powdered gum arabic or karaya gum.

foil assistant,

n See foil holder.

foil, cohesive gold,

n a gold foil that has been annealed or had a surface so completely pure so that it will cohere or weld at room temperature.

foil, corrugated gold,

n a gold foil made by burning gold foil sheets between paper in the absence of air.

foil cylinder,

n a cylinder of gold foil formed by repeatedly folding a sheet of foil into a narrow ribbon, which is then rolled into cylindrical form.

foil, gold (fibrous gold),

n pure gold that has been rolled and beaten from ingots into a very thin sheet. Thickness usually varies from 1/40,000 inch (No. 2 foil) to 1/20,000 inch (No. 4 foil). Classified as cohesive, semicohesive, or noncohesive. One of the oldest restorative materials, the most permanent if used properly, and the yardstick by which all others are measured. It is compacted or condensed into a retentive cavity form piece by piece, using this metal's property of cold welding.

foil holder (foil assistant),

n an instrument used to retain a foil pellet in place while it is being condensed or to retain a bulk of gold while additions to it are made.

foil, noncohesive gold,

n a gold foil that will not cohere at room temperature because of the presence on its surface of a protecting or contaminating coating. If the coating is a volatile substance, such as ammonia, the foil may be rendered cohesive by heating or annealing it to remove the protection.

foil passer (foil carrier),

n a pointed or forked instrument used to carry pellets of gold foil through an annealing flame or from the annealing tray to the prepared cavity for compaction.

foil pellet,

n See pellet, foil.

foil, platinized gold

(plat´nīzd),
n a form rolled or hammered from a “sandwich” made of platinum placed between two sheets of gold; used in portions of foil restorations where greater hardness is desired.

foil, platinum,

n pure platinum rolled into extremely thin sheets. A precious-metal foil whose high fusing point makes it suitable as a matrix for various soldering procedures; also suitable for providing the internal form of porcelain restorations during fabrication.

foil, tin,

n a base-metal foil used as a separating material, or protective covering (e.g., between the cast and denture base material during flasking and curing procedures).