Abrasive blasting
Surface preparation before coating
Steel structures, tanks, pipelines, ships and industrial plant. Sharp, sub-angular grains cut a crisp anchor profile and leave very little salt behind.
Grades8/80 Alpha Blast36#20/60
GRM Garnet is 98% almandine garnet for abrasive blasting, waterjet cutting and water filtration. Every grade reaches the top Sa 3 blast finish, with chlorides 40–60% below the ISO limit.
Eight graded sizes, coarse 8/12 to fine 120#
“Garnet” is a family name, not a specification. Two bags with the same label can perform very differently on the job. GRM Garnet is almost pure almandine, the iron–aluminium garnet that ranks among the hardest and heaviest, so more of every tonne cuts and less of it turns to dust.
7.5–8.0 on the Mohs scale, above the 6.5–7.5 commonly published for garnet abrasives. At specific gravity 4.00, each grain hits harder than sand, slag or glass.
From coarse 8/12 to fine 120#, every GRM grade reaches Sa 3, the top ISO 8501-1 cleanliness grade: visually clean steel with a uniform metallic colour.
10–15 ppm water-soluble chlorides and 0.5% free silica, half the 1% line NIOSH recommends. Radioactivity is not detectable.
Coatings fail from underneath. Salt left on blasted steel draws water through the paint film and drives blistering and corrosion under the coating, often long after the job is signed off. GRM Garnet sits 40–60% inside the ISO limits for chlorides and conductivity, so far less salt reaches the steel.
Request a QuoteEvery abrasive has a price per tonne. What decides the real cost is how fast it cleans, how much is used, what it leaves on the steel and in the air, and what has to be disposed of afterwards.
In the same NIOSH programme, silica sand had the lowest price per ton and the highest cleaning cost per square foot.
Third-party results describe garnet as an abrasive type, from trials commissioned by the US National Institute for Occupational Safety and Health.
The hardness, weight and clean chemistry that make GRM Garnet a premium blast abrasive also make it a standard waterjet abrasive and a proven filter medium.
Surface preparation before coating
Steel structures, tanks, pipelines, ships and industrial plant. Sharp, sub-angular grains cut a crisp anchor profile and leave very little salt behind.
Hard enough to cut, kind to the cutting head
Garnet is the standard waterjet abrasive. It cuts quickly without the nozzle and mixing-tube wear of harder synthetics, and dense grains carry the stream’s energy into the cut.
The fine, final layer of a multimedia bed
High density keeps garnet at the bottom of the bed after backwashing, beneath lighter sand and anthracite. Coarse garnet also serves as a support bed. Hardness resists attrition for a long service life.
Every grade has a published sieve analysis, so you get a consistent profile and an even feed through the pot or cutting head. Pick a grade to see its typical particle size distribution.
Broad-graded blast abrasive
A wide grading that puts coarse and fine grains to work together. Coarse grains cut depth while finer grains clean the valleys between the peaks, leaving an angular profile for the primer to key into.
Easy to handle on site and easy to stack, for blasting crews, workshops and waterjet operators.
Loose bulk bags for high-volume users, distributors and filter-bed installations.
Product data sheet, size chart and safety data sheet, ready for your specification and procurement files.
NIOSH commissioned a head-to-head study of silica sand and its substitutes, first in the laboratory and then on real structures. Garnet cleaned faster than every other abrasive in the field.
Source: KTA-Tator Inc. for NIOSH (1999), Evaluation of substitute materials for silica sand in abrasive blasting. Averages for each abrasive type, converted from ft²/h and lb/ft². Results describe garnet as a type, not GRM Garnet specifically.
Here is what to request, why it matters, the benchmark to hold it against, and what GRM Garnet typically delivers.
| Ask for | Why it matters | Benchmark | GRM Garnet |
|---|---|---|---|
| Almandine content | Purity sets hardness and weight, and how much of each tonne actually cuts | As high as possible | 98% |
| Hardness | Harder grains cut faster and keep their edge for longer | ISO 11126-10 minimum: 6 Mohs | 7.5–8.0 Mohs |
| Specific gravity | Heavier grains strike the surface with more energy | Garnet commonly 3.5–4.3 | 4.00 |
| Water-soluble chlorides | Salt left on steel drives blistering and under-film corrosion | ISO 11126-10 maximum: 25 ppm | 10–15 ppm |
| Conductivity | A quick measure of total soluble salts | ISO 11126-10 maximum: 250 µS/cm | 100–150 µS/cm |
| Free silica | Breathing crystalline silica dust causes silicosis | NIOSH: avoid abrasives above 1% | 0.5% |
| Radioactivity | Some mineral sands carry radioactive monazite | Should not be detectable | Not detectable |
| Moisture | Damp abrasive bridges in the pot and feeds unevenly | ISO 11126-10 maximum: 0.2% | Non-hygroscopic |
| Grain shape | Angular grains cut; rounded grains cut less aggressively | Sub-angular or angular | Sub-angular |
| Blast finish | The cleanliness grade your coating specification calls for | ISO 8501-1 top grade: Sa 3 | Sa 3, every grade |
| Sieve analysis | Consistent sizing gives a consistent profile and feed rate | Published for each grade | 8 grades, published |
Everything your engineers, safety officers and buyers need to approve GRM Garnet.
Tell us the grade, the application and roughly how much you need. Enquiries are welcome from blasting contractors, waterjet shops, filtration specialists and distributors anywhere in the world.
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To request a quote, email sales@grmgarnet.com with the grade, application, quantity and country of delivery.
Last updated 14 October 2026
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GRM Garnet · sales@grmgarnet.com · +27 87 151 1378