Dopping cement, dopping wax, or faceting wax is a

thermal adhesive Thermal adhesive is a type of thermally conductive glue used for electronic components and heat sinks. It can be available as a paste (similar to thermal paste) or as a double-sided tape. It is commonly used to bond integrated circuits to heatsink ...

used by gem cutters to secure ("dop") a

gemstone A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, ...

to a wooden or metal holder (" dopstick", "Tounded stick") for

grinding Grind is the cross-sectional shape of a blade. Grind, grinds, or grinding may also refer to: Grinding action * Grinding (abrasive cutting), a method of crafting * Grinding (dance), suggestive club dancing * Grinding (video gaming), repetitive and ...

and

lapping Lapping is a machining process in which two surfaces are rubbed together with an abrasive between them, by hand movement or using a machine. Lapping often follows other subtractive processes with more aggressive material removal as a first step ...

. Setters cement is a similar material used to secure a gemstone while setting or polishing. Dopping cement is usually formulated so that it is hard at room temperature, but soft and moldable like

putty Putty is a material with high plasticity, similar in texture to clay or dough, typically used in domestic construction and repair as a sealant or filler. Although some types of putty (typically those using linseed oil) slowly polymerise and be ...

at 45-65 °C, when it can still be shaped with the fingers. The cement is commercially sold as sticks or flat slabs. With metal dopsticks, a low-melting tin-lead solder can be used for that purpose, instead of a dopping cement.

Use

In typical use, a small amount of cement is melted from the tip of a cement stick or from the edge of a cement slab by holding it over an

alcohol lamp An alcohol burner or spirit lamp is a piece of laboratory equipment used to produce an open flame. It can be made from brass, glass, stainless steel or aluminium. Uses Alcohol burners are preferred for some uses over Bunsen burners for safety pu ...

or similar source of heat. The tip of the dopstick is dipped into the molten cement, which is allowed to cool until it has the consistency of putty. The stone too is separately warmed up to about the same temperature. Then the dopstick is pressed down over the stone, and the cement is pressed with the fingers so as to tightly enclose it, except for the part that is to be ground or polished. Alternatively, the stone may be warmed up to that temperature, and a few drops of molten cement can be dropped over it. The dopstick is then placed over the stone, and the cement is pressed around it. The stone can be removed from the dopstick by warming the cement again. Alternatively, the cement can be further cooled with cold water, so that it becomes brittle, and then the stone is pried out with a knife.

Composition

Dopping cement can be made from several materials, including * Shellac *

Chasers pitch Chaser's pitch is a thermal adhesive used by goldsmiths, silversmiths, coppersmiths, and other metal cold-working artisans to hold a metal plate for repoussage and "chasing" (embossing) while it is being hammered out. Generally, chaser's pitch ...

* Sealing wax *

Beeswax Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive workers ...

Commercial cements may have other formulations. Formulations with higher melting point, like 65-75 °C, tend to be harder at room temperature and thus hold the stone more firmly. However, they may be too hot to mold with bare fingers; and some gemstones (like

opal Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline forms ...

and

turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of yea ...

) are easily damaged by heat.

References

H. Dake (2013):
The Art of Gem Cutting - Including Cabochons, Faceting, Spheres, Tumbling and Special Techniques
'. Read Books; 98 pages. Mohsen Manutchehr-Danai (2013): ''Dictionary of Gems and Gemology''. Springer; 565 pages. John Sinkankas (2014):
Gem Cutting: A Lapidary's Manual
', 2nd Edition. Echo Point; 322 pages. Bill James (1965): ''Collecting Australian Gemstones''. Murray; 191 pages. (2019):

; featuring brown, green, and black dop wax sticks. Graves Company online catalog page. Accessed on 2019-04-19. (2019):

; reddish brown, as a 1/4 pound square slab. Romanoff company online catalog page. Accessed on 2019-04-19. J. Sean Keane (2019):
Choosing The Best Faceting Wax For Your Task
. Online advice page, International Gem Society. Accessed on 2019-04-19. {{DEFAULTSORT:Dopping cement Visual arts terminology Jewellery making Adhesives

Use

Composition

See also

References