Abrasive blasting (AKA media blasting) is a quick and effective way to remove layers of paint or years of corrosion. The process uses high-pressure air to shoot abrasive particles at parts to clean, strip, or otherwise modify their surface. However, choosing the correct blast media is key to determining how quickly, how effectively, and (importantly) how safely.
In this guide, we spell out which common abrasive blast media work best for which materials, from glass beads to walnut shells. With DIY auto restorers in mind, we’ll examine material compatibility, optimal usages, and essential precautions.
Safety First
Regardless of which media you end up using – or whether you blast in the open air or inside a cabinet – certain safety precautions should always be taken. Dry blasting creates dust that includes not only the blast media but also particles of whatever is blasted off your work. This may include rust, old lead paint, or any number of potentially hazardous industrial contaminants. At the bare minimum, a dust mask should be worn whenever you blast, even in a cabinet. If you’re blasting a known toxin (lead paint, for example), consider wearing a fine-filtering respirator.
The same goes for eye protection, especially when blasting in an open environment. Dust generated by blasting can irritate your eyes, so consider wearing a face shield or goggles. Better yet, wear a blasting hood. And don’t forget your hands. Special blasting gloves are essential to prevent skin damage from exposure to high-pressure abrasives. A pair of heavy rubber, gauntlet-style gloves is essential for open-air blasting. If you’re using a blast cabinet, make sure the built-in gloves are fully connected and not torn or worn through.
One more note. As you look through the list of abrasives below, you may notice one material is not even on the list. Sand. While silica sand, the kind in your kid’s sandbox, was once commonly used for blasting, that’s not the case today. That’s because of the danger of inhaling the fine crystalline silica dust. Exposure can cause silicosis, a respiratory disease that causes shortness of breath, severe respiratory inflammation, and permanent lung damage.
Silicon Carbide
Silicon carbide is an aggressive material used for stripping rust and paint from hard surfaces.
Best suited for: Hard metals
Not recommended for: Softer metals (can be overly abrasive), delicate materials like plastics or fiberglass
Aluminum Oxide
Aluminum oxide is a versatile abrasive well suited to removing paint, rust, and scale from a variety of metal surfaces.
Best suited for: steel, iron, and other hard metals
Not recommended for: Soft or non-ferrous metals (can be overly abrasive), delicate materials like plastics
Sodium Bicarbonate (Baking Soda)
Soda blasting is great for removing paint, rust, and grease from metal surfaces. Sodium bicarbonate media, also known as baking soda, cleans these materials effectively without causing damage to the substrate, leaving behind a lightly etched finish.
Best suited for: Aluminum and other soft metals, plastics, and fiberglass
Not recommended for: Hard metals where more aggressive abrasives are needed, or other materials requiring a rougher surface profile
Glass Bead
Bead blasting is a common form of blasting in many restoration shops. Glass beads are ideal for cleaning and polishing metal surfaces without etching or damaging the material. Crushed glass is similar but more aggressive, an alternative to traditional sand.
Best suited for: Steel, aluminum, stainless steel, and delicate surfaces like fiberglass or chrome
Not recommended for: Hard or brittle materials like cast iron, as well as thick/ heavy rust or scale
Walnut Shells
Walnut shell media is exactly what it sounds like. Ground-up shells are a gentle option, suitable for removing paint and light rust without damaging the underlying metal. Walnut shells are also biodegradable and less abrasive, making them safer for certain applications.
Best suited for: Soft metals, plastics, and fiberglass
Not recommended for: Hard metals where more aggressive abrasives are required, or other materials that need a high level of surface roughness