How to select grit for sandblasting

Written by j. lang wood
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How to select grit for sandblasting
Corn cob is a sandblasting grit used to clean log homes. (Jupiterimages/Photos.com/Getty Images)

Sandblasting is an industrial process in which abrasive particles are shot across the surface of material at high speed. It is used to remove paint and other coatings and to etch the surface of material to receive a new finish. Sand was the original abrasive used for the process, but many different kinds of substances are now used. Deciding which kind of grit, also called "media," to use is based on the material being sandblasted and the processes for which the materials are prepared. The sandblasting process requires special equipment and skills, and is potentially dangerous for the operator.

Skill level:
Challenging

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Things you need

  • Sandblasting equipment
  • Parts to be sandblasted
  • Air-supply respirator
  • Clothing protection
  • Goggles
  • Sandblasting cabinet

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Instructions

  1. 1

    Sandblast wood with a softer grit than you would use on metal. Aluminium requires a gentler grit than steel. Brass or fibreglass requires an even softer abrasive media. The type of material you are sandblasting determines which type of grit you must use.

  2. 2

    Remove individual layers of paint, while leaving body primer or filler material intact, by using plastic beads. Corn cob is considered a very effective grit for sandblasting log homes. Walnut shell is an angular medium that does not damage the underlying substrate material. Glass beads often are used on small, precision parts because they will not add chemical components or change the dimension of parts.

  3. 3

    Calculate abrasive media costs. Some types of grit are more expensive than others and add considerable cost to the finished product. Glass beads are recoverable and reusable up to 30 times, which make this quite economical for deburring -- removing raised bits or jagged edges left from industrial processes. This grit also can be used for paint removal.

  4. 4

    Weigh the environmental impact of your choice of abrasive grit. Plastic beads are made of acrylic, melamine or urea, which require proper reclamation and disposal. Corn cob and walnut shells are organic materials that will not harm the environment, but are perhaps unsuitable for all sandblasting projects. Soda blasting, done with sodium carbonate, can damage animals and plants.

Tips and warnings

  • Soda blasting is often used for sandblasting of products used in food manufacturing because it is nontoxic and has a deodorising effect, according to Sandblasting Authority.
  • Dry ice sandblasting, which uses tiny pellets of frozen carbon dioxide, is a new alternative to traditional blasting grit. The process lifts the layer from the surface without abrading the underlying surface. It does not leave behind a chemical residue or grit media.
  • Use the harshest types of grit only for steel surfaces, according to Kramer Industries. Steel shot comes in a variety of sizes and can effectively remove layers of paint from steel surfaces. It is not a good choice for aluminium or other materials that abrasion can damage.
  • Many types of sandblasting grit contain lead, cadmium, manganese and silica sand, according to ToolBoxTopics. These are hazardous to inhale and can cause lung problems. Use air-supplied respirators and remove contaminated clothing to prevent health problems.

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