Olivine sand is a blasting abrasive made from crushed and graded olivine rock, used under high pressure to clean facades, floors and coatings. Olivine is a green magnesium-iron silicate; the name comes from the Latin oliva (olive), after the olive-green colour of the mineral.
Why olivine is used
The key property is that olivine contains no free crystalline silica. Blasting with quartz-bearing sand is prohibited or heavily restricted in most of Europe because of the risk of silicosis; olivine sand falls outside that restriction and is therefore a common substitute. It is also hard enough to remove dirt, paint and coatings, yet less aggressive than steel grit.
> Even without silica, blasting is still dusty, noisy work. Respiratory protection, eye protection and hearing protection are essential, and facade work requires the surroundings to be sheeted off.
Applications
- Facade cleaning — removing soiling, algae, paint residues and old coatings
- Floor cleaning — keying or removing coating and epoxy layers
- Surface preparation — a blasted surface gives better adhesion for a new paint or coating system
- Wet or mist blasting — the sand is metered into a water jet, so very little dust is released and the impact on the surroundings stays limited
Grain size determines aggressiveness: a fine grade for delicate masonry and natural stone, a coarser grade for stubborn coatings on concrete or steel.
Points to watch
- Always start with a test patch — old, soft brickwork and clay tiles can lose their fired skin when blasted, after which they soil faster and absorb more water
- Set the pressure as low as possible while still achieving the result
- Collect the spent abrasive — it contains the residue of whatever was removed and may have to be disposed of as contaminated waste
- On listed and historic buildings, blasting is normally only permitted after consultation with the conservation authority
Related terms
- Blasting
- Grit blasting
- Facade cleaning
- Water repellent treatment
- Repointing
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