Tinfoil
The tinfoil (from the Latin stagnum, stannum , originally a lead silver alloy, later tin), also tin foil , is a thinly rolled or hammered foil made of tin . Today the term is also used colloquially for foils made of aluminum ( aluminum foil ), since products made from the much cheaper aluminum have replaced tinfoil from its areas of application.
Nowadays, tinfoil is only used in exceptional cases for packaging food (e.g. for wine capsules, screw caps , for cheese maturation , etc.). It is also used in special technical applications in laboratories and in medical technology ( electrodes ). The material can also be found in metal foil capacitors and as decorations and Christmas tree decorations ( tinsel ).
Manufacturing
Tinfoil is made from cast plates of about 1 ⁄ 2 square meters in several steps in rolling mills. Tin alloys can be rolled out to a thickness of 5 µm ( 1 ⁄ 10 the thickness of a hair ). Tinfoil made from pure tin cannot be rolled quite as easily and is rolled to a thickness of just under 20 µm. The strips rolled in this way are several kilometers long.
history
Tinfoil has been known since the 17th century. Tinfoil was made from very thin tinplate made of pure tin or a tin alloy with z. B. 1 to 2 percent copper produced by casting, rolling and hammering. The metal was poured into plates with a thickness of 10 mm and these plates were rolled in a sheet-metal rolling mill, initially individually, then several placed one on top of the other, into sheets up to a thickness of 100 μm.
Another method was to keep tin liquid in a long bowl; Above this bowl was a roller that was just as long covered with canvas. This roller was lowered into the tin and turned over once, covering itself with a thin layer of tin. This layer was unwound and placed on a polished flat stone. About 300 more such 100 µm thick sheets were added to this layer.
Even thinner tinfoil was then made from these sheets or leaves by hitting them with hammers in the same way as gold leaf (see: Goldschläger ) .
Due to the high expenditure of time and personnel, the historical production methods are only used in exceptional cases.
use
Together with mercury, tinfoil was used to cover mirrors and was given a thickness of 38 to 500 µm for this purpose. Tinfoil for wrapping tobacco, soap, chocolate, etc. was 7.7 to 150 µm thick. Tin foil containing lead was also produced in many cases, either from alloys or from lead plates over which tin was poured. In order to prepare colored, shiny tin foil, tin foil was cleaned with cotton and chalk powder, coated with gelatin solution, colored with berberis , litmus , orseille or saffron decoction or aniline solution and, after drying, coated with alcohol varnish.
In organ building tin foil has been used since the 16th century to partially visible pipes made of other material ( copper , zinc to conceal) and to adapt them to pipes made entirely of organ metal were.
Since the 17th century, tin foil has been used to decorate slate gables in Thuringia and Franconia (so-called tin foil painting ).
In military use, thin tinfoil strips with a precisely defined length were used as decoys to protect against radar detection . There such strips are called chaff (in English usage “chaff”) and today mostly consist of metal-coated synthetic fibers or conductive carbon fibers . During the Second World War, the British Army captured a Würzburg radar through Operation Biting in order to determine the appropriate length of tinfoil for the frequency used. One of the most well-known uses of tin foil strips for protection on location took place during Operation Gomorrah over Hamburg.
Tinfoil is still in use today for the production of tinsel .
During the dental production of a full denture , the torus palatinus , a bony protrusion on the palate , is "relieved" by placing a tin foil about 1 to 2 mm thick on the plaster model over the torus during the production of the upper jaw prosthesis . This creates a cavity in the final prosthesis that corresponds to the flexibility of the mucous membrane.
literature
- Karl Richter (Ed.): Zinc, tin and lead. A detailed description of the properties of these metals, their alloys with each other and with other metals, as well as their processing in physical and chemical ways. For metal workers and art industrialists . (= Chemical-technical library ; vol. 109), 3rd edition, A. Hartlebens Verlag, Vienna and Leipzig 1927, p. 149 ff.
