History of the sandblast

The desert violent winds
The abrasive action of the sand projected by a violent wind on hard bodies (rocks, monuments) is a well-known phenomenon since the Antiquity. Its study often allowed the archaeologists to determine to an approximate date the erection of a monument.
Faced with tortured and curiously jagged shapes of some Saharan massif, in particular the Hoggar, the geologists studied this fantastic erosion agent.
When the "Simoun" blows a gale, it raises and carries the desert sand and the infinite repetition of these small grains impact on the more or less hard rock produced so strange effects that one can sometimes recognize the stamp of some Cyclopean and eccentric sculptors.
This phenomenon can be observed in a good many places worldwide. The Yellow Cruise brought us startling examples.
The so fine sand called the "Loess", almost pulverulent, remains for weeks hanging on the air. Sometimes the winds carry it thousands kilometres away, digging gradually the valleys and jagging on its way the rocks which take tortured and strange shapes.

Western legend
The progresses of mechanics allowed turning to good account this natural phenomenon at the end of the XIX century only. It is generally admitted that the idea germinated in South America where the first abrasive projection equipments were built.
A legend claims that a citizen of the United States living probably in a Western sandy plain exposed to violent winds was unpleasantly surprised by the tarnishing action of sand-laden wind on the panes of the windows of his farm. He protected them with louvers and their shape be immediately reproduced identically on the panes. This natural phenomenon will be at the origin of a technique with patents and successive adjustments.

History of the sandblasting

Patents
This unexpected observation of sand-laden winds action leads TILGHMANN, chemist in Philadelphia and inventor of the air compressor, to find out their reproduction in order to facilitate the work of stone, glass or other materials.
In 1870, it registers a first patent thus described:
"A shot stream hurled to high speed by a steam or a draught is used as a tool to cut the stone and other materials. If it is hurled to a lower speed, it is used to grind down and ornament the glass surface."
En 1872, in the additional patent, TILGHMANN thought about the shot stream use to:
"cut, drill, frost, smooth, pulverize and engrave stones, metals, glass, wood and other hard or solid materials; clean and level the surfaces of the molten or beaten articles, and remove slags, scales and any other residues; prepare metals with tinning, enamelling, or to be covered with metal substances or other."

Evolution
The sand, formerly projected by steam in accordance with a suction process as the one of the French engineer GIFFARD, becomes wet, sticks and clogs piping. The results are disastrous with a quick oxidation of parts. It is not an economic success and the progresses are very slow.
In 1878, RICHARDSON uses the shot stream to sharpen the files by inclining it under an angle of 15°. The abrasive is always carried along by a steam current under a pressure from 4 to 5 kilogrammes.
In 1884, MATHEWSON brings some adjustments which tend to eliminate the disadvantages due to the use of steam as a fluid vector. The process is rather improved but its output remains low.
In 1885, the sandblasting enjoys a new boom thanks to the development of the air compressor allowing the replacement of steam by dry compressed air. The output is still low but the researches turn towards new and above all more economical processes.
In 1886, GUTMANN realized the importance of TILGHMANN's patent and built the first machine called "suction sandblasting machine". This is the oldest known in Europe. The so called sandblasting technique was born.
In 1893, GUTMANN obtained his first patent for a "compressed air sandblaster". It was a machine in which the sand was pressurized in a single pressure chamber. The sand conveyance was facilitated and the output increased. Called "air sandblasting machine", it is still built and used nowadays.
In 1895, MATHEWSON invents the "pressure reducer of air" and an air/ sand mix valve, which will be the basis of all the installations so far.
In 1905, to automate work, sandblasters with double pressure chambers are developed. They provide a continuous sand outflow and allow the tank to be supplied with abrasive, without stopping the installation.
From 1913 to 1915, with the appreciated apparition of metal abrasives, many patents on the "centrifugal wheels" are registered, but without any practical application.
In 1928, HOLLINGSWORTH registers a patent on a projection technique by centrifugation, known as "blast wheel" and using angular shots and treated steel beads.
In 1937, EPPLER devises the "wet way" process in which the vector remains the compressed air but where the abrasive is canalized in a torrent of water. This process allows the use of very low bead size while reducing the calorific effect due to the numerous impacts on the part.
In 1939, the increase in the industrial production caused by the Second World War is at the origin of the use of "fine" abrasives such as Quartz, Aluminium Oxide and Silicon Carbide. The search for "soft" solutions caused afterwards the apparition of organic abrasives such as fruit stones or crushed walnuts shells.
The Aircraft industry initiated the use of glass beads and of plastic abrasives in many delicate operations of surfaces treatments. Finally, the ceramic beads with a voluminal mass halfway between steel and glass were invented.