Selecting an Appropriate Media
- Sand used to be the only media used with media blasting. However, over time it was discovered that blasting with sand can cause respiratory damage known as silicosis. Many states now actually prohibit the sale and/or use of sand for blasting purposes. Thankfully, today there are many different forms of blasting media available, each designed for a particular purpose. Glass bead is best for cleaning aluminum, brass and die-cast metal. Ground glass and aluminum oxide are both excellent choices for removing carbon, rust and paint. Recently, sodium bicarbonate is becoming a more popular choice to remove paint because it is water soluble and does not harm glass or chrome, which is especially attractive when blasting a vehicle. However, sodium bicarbonate tends to be the most expensive type of media and is not effective at removing heavy rust.
- No matter which type of media is selected, the importance of safety cannot be stressed enough. Blasting media poses a serious respiratory hazard and can also quickly damage the skin and eyes. In addition, because media blasters are powered by compressed air, thereby requiring an air compressor, blasting for long periods of time can also cause permanent hearing loss. Every type of media is measured in grit, which represents the approximate size of each individual particle. To protect the nose, throat and lungs, it is important to always wear a respirator which is specifically designed to filter the grit size of the chosen media. To protect the eyes, safety goggles should always be worn. To protect the skin, always wear a long sleeve shirt and leather gloves. Finally, ear plugs or muffs should be worn.
Proper Blasting Angle
- When the media exists the blasting nozzle, it does so in a fairly straight line. When the media strikes the surface it removes the media by literally ripping it away. It does so by grasping on the edges of the material. If the media is applied directly to the face of the material, the media does not have much of an edge to grasp. Therefore, it is important to always apply the blasting material at a slight angle to the material to be removed.
- Warpage, as used as an automotive term, is used to describe the distortion of metal. As the blasting material strikes the metal surface, it quickly creates heat due to the friction caused by the blasting material passing over the metal. The heat causes the metal to expand, typically in an outward direction. Once the metal has warped, it must then be repaired. Warpage can be avoided by not concentrating the blasting material on the same area for more than two or three seconds at a time.