What is Sand blasting?

Sandblasting, also known as abrasive blasting, is a method for cleaning, smoothing, or shaping surfaces by blasting abrasive media with high pressure on the surface of the parts. It’s a go-to technique in industries like construction, manufacturing, and restoration, where it’s used to remove rust, paint, or grime from surfaces like metal, wood, or concrete. The abrasive is fired through a nozzle using compressed air or a spinning wheel, stripping away unwanted layers or texturing the surface as needed.

Types of Sand in Blasting

Sand blasting relies on different abrasive materials to get the job done, and picking the right media is key to achieving great results. Here’s a list of the most common sand blasting media.

Silica Sand

Silica sand, made mostly of silicon dioxide, was once the go-to abrasive for sand blasting because it’s effective and easy to find. With a hardness of about 7 on the Mohs scale, it works well for all sorts of tasks. But its popularity has dropped due to health risks from silica dust, which can harm your lungs, pushing people toward safer alternatives.

Crushed Glass

Crushed glass is becoming a favorite option due to its eco-friendly vibe and solid performance. It weighs around 75-80 lbs per cubic foot, making it lighter and less aggressive than heavier options like garnet (about 145 lbs per cubic foot). When used at the same size and pressure, crushed glass gives a gentler finish, perfect for delicate applications where you don’t want to rough up the surface too much.

Garnet

Garnet is a heavier, tougher abrasive that packs a punch. Its higher density makes it ideal for heavy-duty cleaning or prepping surfaces, especially when you need to blast away thick rust or paint. It’s a top choice for jobs that demand serious material removal.

Baking Soda

Baking soda (sodium bicarbonate) is a gentler option for jobs where you don’t want to scratch or etch the surface. It’s great for things like fire damage cleanup, paint removal, or mold fixes. It’s a one-and-done material that soaks up moisture, so you’ll need clean, dry air to keep it working well.

Walnut Shells

Walnut shells are a biodegradable, non-toxic choice with a hardness of 2.5 to 4 on the Mohs scale. Their rounded shape makes them gentle yet effective, especially on softer materials like wood or plastic, where avoiding damage is a priority.

Other Abrasives

Beyond these, you’ve got synthetic silica, carbon materials, and silicon carbide, which can be mixed in to boost performance. The right pick depends on the project condition, whether you’re aiming for a specific finish or working with a tricky material.

What Makes Blasting Sand Effective?

Sand blasting is all about choosing the right abrasive, and the properties of the sand (or other material) can make or break the result. Here’s what matters:

Abrasive Characteristics

Good blasting sand needs to be hard enough to do the job. Most sands used contain quartz (7 on the Mohs scale) or feldspar (6), giving them the toughness to smooth or rough up surfaces. For extra oomph, synthetic abrasives like silicon carbide, garnet, or carbon materials can be added, especially when tackling harder surfaces that need aggressive cleaning or prep.

Particle Shape and Size

The shape of the abrasive changes how it works. Angular particles like crushed glass or slag have sharp edges that dig into the surface, leaving a rough “anchor profile” that helps coatings stick better. Round particles, like glass beads, are better for cleaning and leave a smoother finish without much texture. Size matters too because coarser grains blast away material faster but can leave a rougher surface, and finer grains take longer but give a polished look.

Anchor Profile

The anchor profile is the peaks and valleys left on the surface. which is critical for making paints, sealants, or finishes stick properly. Measured in mils (thousandths of an inch), this texture varies based on the abrasive and technique. Some folks want a rugged surface for better grip, while others prefer something smoother.