Search results
Results from the WOW.Com Content Network
Ptolemaic Egypt had manufactured small glass mirrors backed by lead, tin, or antimony. [4] In the early 10th century, the Persian scientist al-Razi described ways of silvering and gilding in a book on alchemy , [ citation needed ] but this was not done for the purpose of making mirrors.
Whether silver plating or pure silver, the composite of the metal will tarnish when exposed to air and sulfur. Tarnish is a chemical reaction on the surface of metal (copper, brass, silver, etc.) and causes a layer of corrosion. In the case of silver tarnish, the silver combines with sulfur and forms silver sulfide (Ag 2 S), which is
The simplest optical coatings are thin layers of metals, such as aluminium, which are deposited on glass substrates to make mirror surfaces, a process known as silvering. The metal used determines the reflection characteristics of the mirror; aluminium is the cheapest and most common coating, and yields a reflectivity of around 88%-92% over the ...
Mercury glass (or silvered glass) is glass that was blown double walled, then silvered between the layers with a liquid silvering solution, and sealed. Although mercury was originally used to provide the reflective coating for mirrors, elemental mercury was never used to create tableware.
Glass block wall in Chicago. Glass blocks can provide light and serve as a decorative addition to an architectural structure, but hollow glass blocks are non load-bearing unless stated otherwise. Hollow glass wall blocks are manufactured as two separate halves and, while the glass is still molten, the two pieces are pressed together and annealed.
Binding of the glass in the frame, causing stresses to develop as the glass expands and contracts due to thermal changes or deflects due to wind. Glass expands and contracts with changes in temperature and deflects due to wind, so almost all modern glass is set on resilient blocks at the bottom and with space for expansion at the sides and top.
Silvered glass mirrors were a vast improvement, since silver reflects 90% of the light that hits it and is much slower to tarnish than speculum. Silver coatings can also be removed from the glass, so a tarnished mirror could be resilvered without changing the delicate precision-polished shape of the glass substrate.
In all types of cases, the inside of the cover was lined with velvet or plush or satin to provide a dark surface to reflect into the plate for viewing and to protect the cover glass. [74] Some cases, however, held two daguerreotypes opposite each other. The cased images could be set out on a table or displayed on a mantelpiece. Most cases were ...