Sand for Sandblasting: Which Media to Use, and What They Do

Sand for sandblasting, and the media that replaced it

In an Indian factory the answer is not sand. Free silica abrasive is prohibited there, so copper slag, garnet, steel grit and shot, aluminium oxide and glass bead do the work instead. What almost nobody tells you is that the substitutes are not all safer, and the regulator that says so is worth reading before you place the order.

Flexihose sand blast hose: 175 PSI / 12 BAR working · 700 PSI / 48 BAR burst · 1/2" to 2" bore · DIN abrasion loss below 60 mm³ · Exceeds IS 5894

Which sand is used for sand blasting in India?

In a factory registered under the Factories Act, none. Sand, or any other substance containing free silica, is prohibited as an abrasive for blasting. That prohibition sits in the Factories Rules rather than in the Act, which is why it is easy to miss, and it is decades old rather than new. Who it covers, what it does not cover, and the exemption route are all set out in our guide to the silica rules. This page is about what goes in the pot instead.

Working on a Saudi Aramco site? Aramco prohibits silica sand at all its facilities and projects, prohibits reclaimed slag, and allows reclaimed garnet only through an approved recycling system. Those rules, and how the blast hose is grounded there, are in our guide to sandblasting sand in Saudi Arabia.

Can you use normal sand? No, and the reason is not only legal. Building sand, river sand and beach sand are graded for concrete, or for nothing at all. The particle sizes are uncontrolled. The moisture bridges in the pot and chokes the line. Shells and organic matter come with it. And the quartz content is exactly the hazard the rule exists to remove. A blasting abrasive is a manufactured or screened product with a stated grade, bought as such.

Outside a factory the position is different, and the Flexihose catalogue is written for both: this hose is rated for the cleaning and blasting of casting metal, stone and concrete surfaces, with wet or dry sand or other abrasive material. The hose does not care what the law says. It is the lining that has to survive whatever you chose.

The substitutes are not automatically safer

This is the part the supplier’s catalogue leaves out, and it is the reason this page exists. Indian law removes free silica from the pot. It does not certify what you put in its place. The clearest public statement on the alternatives comes from the United States Occupational Safety and Health Administration, in a four page fact sheet on the hazards of abrasive blasting materials.

OSHA groups what it calls commonly used abrasive materials as silica sand, coal slag, garnet sand, nickel slag, copper slag, glass in bead or crushed form, steel shot, steel grit and specular hematite. Against those it sets out what each is known or suspected to do to a lung, and the ranking is not the one most buyers assume.

Read the second row again. Garnet is the abrasive most often recommended in India as the clean alternative to sand, and OSHA’s fact sheet puts it in the same sentence as coal slag for lung damage similar to silica sand. Copper slag, which is the volume choice on structural steel here, sits one row below with the potential to cause lung damage, and carries the trace metal warning as well.

None of that makes these abrasives unusable. It makes the dust controls non optional whichever one you buy. OSHA puts substitution first among its engineering controls and immediately pairs it with the other half of the answer: use abrasives that can be delivered with water to reduce dust. Containment, ventilation and a Type CE airline respirator with a positive pressure blasting helmet come next, and none of them become unnecessary because the sand went away. The Indian requirements for enclosure, ventilation and breathing air are in the same guide to the rules.

Copper slag

Copper slag is the default on Indian structural steel for one reason above all others: it is cheap, it is available in tonnage, and it cuts fast. It is an expendable abrasive: used once, then disposed of rather than recovered and screened. That suits open site work, where there is no recovery system anyway. It suits a cabinet or a blast room far less, because there you would be throwing the economics away.

Because it is angular and hard, it is also among the harder media on the inside of a blast hose. What the media choice does to the line, and why the lining specification matters more with angular abrasive than with round, is covered in shot blasting versus sandblasting versus grit blasting.

Garnet

Garnet is the abrasive people move to when they want less dust and a cleaner recovered product, and its manufacturers describe it as durable enough to be recycled multiple times, which reduces overall material cost. On a job with a recovery system that is the whole argument: you buy it once and run it several times, and the disposal volume falls with it.

It is also the abrasive most commonly presented in India as the safe answer to the silica rule, and that is where the OSHA line above matters. Low dust is not the same as low hazard. Garnet is a good abrasive chosen for good reasons; it is not a reason to take the helmet off.

In India there is a second constraint on reuse that is easy to overlook: where abrasive is recovered and used again, the Rules require it to pass through apparatus that separates it from the dust before it goes back round. That is a requirement on the equipment, not just good practice.

Steel shot and steel grit

These are the two OSHA rates lowest for lung damage, and they are also the two that a recovery system is built around. That is not a coincidence: a medium designed to be picked up, screened and thrown again is a medium that is not meant to leave as dust. On a concrete floor this is the whole basis of the method, which is why blasting a concrete floor is usually a shot blasting job rather than a hose and nozzle job.

Shot and grit are ordered by a size number, and the numbering is the part people get wrong.

How to read an S number and a G number. Both come from SAE J444, Cast Shot and Grit Size Specifications for Cleaning and Peening, issued by SAE International’s Surface Enhancement Committee and last revised on 27 June 2023. For shot, the number after the S is the nominal test sieve opening expressed in ten thousandths of an inch, so S230 refers to a sieve opening of 0.0230 in. For grit, the number after the G is the sieve designation itself, taken from ASTM E11, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves. They are two different numbering conventions wearing the same kind of label, which is why a G number and an S number cannot be compared as though bigger means bigger in the same way.

Aluminium oxide

Aluminium oxide is what you reach for when the job needs a hard, sharp cut and a grade you can order again next month and get the same thing. It costs more than slag by a wide margin, so it belongs in a cabinet or a blast room where the media is recovered, not on open site work where it leaves with the sweepings.

It is not on OSHA’s commonly used list, so the fact sheet makes no statement about it, and neither will we. Read the manufacturer’s safety data sheet, which OSHA notes suppliers are required to provide for the blasting material.

Glass bead and crushed glass

Glass bead is the finish medium. It cleans and leaves a soft uniform sheen without cutting a deep anchor pattern, which makes it right for cosmetic work and wrong for a surface that has to hold a high build coating. If the specification calls for a profile, a bead will not give you one. Crushed glass is a different product with a different job, and OSHA lists both together.

Round media is also the gentler of the two shapes on a blast hose bore. That is the one property on this page that changes what you buy from us rather than what you buy from an abrasive supplier.

Which media for steel, stone, concrete and aluminium?

Media is chosen by the job, not by a league table. The question that decides it is usually not which abrasive is best but whether the abrasive can be recovered, because that flips the economics between an expendable medium and a recyclable one.

Two of these rows carry a trap worth naming. On aluminium, steel media leaves iron behind in the surface and the part rusts later in a way the customer will blame on the finish. And on any job where a coating follows, the medium sets the profile but the cleanliness grade is a separate specification entirely, measured against ISO 8501-1 and the Sa grades, not against what came out of the pot.

Media that are barely abrasives at all

Where the work is cleaning rather than profiling, the answer may not be a mineral at all. OSHA lists a set of materials it describes as alternative, less toxic blasting materials: ice cubes, dry ice, plastic bead media, sponge, sodium bicarbonate, ground walnut shells and ground corn cob and other biodegradable materials, and high pressure water.

These come into their own on heritage stone, on food plant, on electrical equipment, on soft substrates, and anywhere the residue itself is a problem. Dry ice sublimes and leaves only what it removed. Soda rinses away. Walnut shell is soft enough to strip paint without touching the metal underneath. They cut slowly or not at all, so they are not a substitute where a specification calls for an anchor profile.

The full sequence a blasting and coating job runs through, whatever is in the pot, is set out in the sand blasting process guide and in the blasting and painting procedure.

Whatever is in the pot, it travels down the same hose

Every medium on this page is accelerated to working speed inside a rubber tube before it ever reaches the work, and the angular ones are cutting the bore on the way past. The Flexihose sand blast hose is built for that duty: an extra thick seamless rubber lining free from mineral filler, high tenacity synthetic yarn braids, and a cover resistant to abrasion, ozone and weather. It exceeds IS 5894. Its DIN abrasion loss is below 60 mm³. It works at 175 PSI / 12 BAR, with a burst of 700 PSI / 48 BAR. It is made from 1/2" to 2" bore and ships in a 40 m standard coil.

Which bore you need follows from the nozzle, not from the medium: that sizing is worked through in compressor and nozzle sizing, and the rest of the line is in blast line parts and setup.