Dolomite is a very popular powder in fossil preparation. It strikes a balance between matrix removal and gentleness on the surface of the fossil, with a Moh’s Hardness of 3.5-4. It is particularly effective on shale, siltstone and limestone. The grains are predominantly angular, providing a moderately gentle cutting action.
Dolomite is a naturally occurring carbonate consisting of calcium carbonate and magnesium carbonate, and is often found with marble having been subjected to high temperatures and pressures during tectonic movements.
Whilst it is enormously effective in fossil preparation when it’s flowing well, dolomite powder is often associated with clogging, clumping and producing large amounts of dust. It also generates a great deal of static and therefore clings to itself, the internal plumbing of your abrasive unit, and the sides of the tank. It must only be used with a super clean, dry air supply (check out the Dropout air filters!). Dolomite powder has a range of grain sizes (predominantly <40μm). We recommend sieving before use.
All that aside, many preparators find dolomite to be totally worth it! There are often a few knacks to getting it flowing (e.g. shaking the tank, sieving before use, filling the tank up only to a certain level, making sure the powder has been in the oven first, etc.), but the results can be phenomenal. If you have not used dolomite before in your unit, we do recommend a 1kg bag to begin with for experimenting on!
Dolomite does not recycle well, as when the grains come shooting out of the nozzle they hit each other along the way causing dusting, which not only reduces visibility but can also cause clogging.
Safety: For blasting applications, only use in a blast cabinet with an appropriate dust extraction system. Use appropriate personal protective equipment. Substance is not a skin irritant, nor a skin sensitiser. Wash skin with plenty of water and soap. Wear appropriate gauntlets when handling in blasting and polishing. In case of contact with eyes, wash immediately with plenty of water. If skin, eye or respiratory irritation persists, seek medical attention. This product is non-combustible. Noxious fumes may evolve in the event of fire. Learn more about Air Abrasives here.