Media
In the early 1900s, it was assumed that sharp-edged grains provided the best performance, but this was later demonstrated not to be correct.
Mineral: Silica sand can be used as a type of mineral abrasive. It tends to break up quickly, creating large quantities of dust, exposing the operator to the potential development of silicosis, a debilitating lung disease. To counter this hazard, silica sand for blasting is often coated with resins to control the dust. Using silica as an abrasive is not allowed in Germany, United Kingdom, Sweden, or Belgium for this reason.
Another common mineral abrasive is garnet. Garnet is more expensive than silica sand, but if used correctly, will offer equivalent production rates while producing less dust and no safety hazards from ingesting the dust. Magnesium sulphate, or kieserite, is often used as an alternative to baking soda.
Agricultural: Typically, crushed nut shells or fruit kernels. These soft abrasives are used to avoid damaging the underlying material such when cleaning brick or stone, removing graffiti, or the removal of coatings from printed circuit boards being repaired.
Synthetic: This category includes corn starch, wheat starch, sodium bicarbonate, and dry ice. These "soft" abrasives are also used to avoid damaging the underlying material such when cleaning brick or stone, removing graffiti, or the removal of coatings from printed circuit boards being repaired. Sodablasting uses baking soda (sodium bicarbonate) which is extremely friable, the micro fragmentation on impact exploding away surface materials without damage to the substrate.
Additional synthetic abrasives include process byproducts (e.g., copper slag, nickel slag, and coal slag), engineered abrasives (e.g., aluminum oxide, silicon carbide or carborundum, glass beads, ceramic shot/grit), and recycled products (e.g., plastic abrasive, glass grit).
Metallic: Steel shot, steel grit, stainless steel shot, cut wire, copper shot, aluminum shot, zinc shot.
Many coarser media used in sandblasting often result in energy being given off as sparks or light on impact. The colours and size of the spark or glow varies significantly, with heavy bright orange sparks from steel shot blasting, to a faint blue glow (often invisible in sunlight or brightly lit work areas) from garnet abrasive.
Read more about this topic: Abrasive Blasting
Famous quotes containing the word media:
“Few white citizens are acquainted with blacks other than those projected by the media and the so—called educational system, which is nothing more than a system of rewards and punishments based upon one’s ability to pledge loyalty oaths to Anglo culture. The media and the “educational system” are the prime sources of racism in the United States.”
—Ishmael Reed (b. 1938)
“Never before has a generation of parents faced such awesome competition with the mass media for their children’s attention. While parents tout the virtues of premarital virginity, drug-free living, nonviolent resolution of social conflict, or character over physical appearance, their values are daily challenged by television soaps, rock music lyrics, tabloid headlines, and movie scenes extolling the importance of physical appearance and conformity.”
—Marianne E. Neifert (20th century)
“The media have just buried the last yuppie, a pathetic creature who had not heard the news that the great pendulum of public conciousness has just swung from Greed to Compassion and from Tex-Mex to meatballs.”
—Barbara Ehrenreich (b. 1941)