Compare Blasting Abrasives
Crushed Glass vs. Coal Slag
Coal slag, sold under names such as Black Beauty and Black Diamond, has been the default blasting abrasive in the Southeast for decades.
It’s a byproduct of coal-fired power plants. Zafa crushed glass is recycled from solar panel and CRT sheet glass in Lawrenceville, Georgia. Here’s how the two compare, and how to work out which costs less on your job.
Crushed Glass vs. Coal Slag: Side-by-Side
| Factor | Zafa crushed glass | Coal slag |
|---|---|---|
| What it is | Recycled solar panel and CRT sheet glass | Byproduct of coal-fired power plants |
| Crystalline silica | [<0.1%] by XRD | Low; check the supplier’s SDS |
| Trace metals | Lot-tested for RCRA metals; results published per grade | Contains trace metals that vary by source, including beryllium, the focus of OSHA’s 2017 beryllium rule for construction and shipyards* |
| Specific gravity | About 2.5 [Zafa measured: x] | About 2.7 |
| Color of blasted surface | Light, bright; easy to inspect | Darker; can leave dark residue |
| Where it’s made | Lawrenceville, GA | Most current plants are in the Midwest |
| Price per 50 lb bag | $7.25–$8.00 in pallet quantities | $13.99 retail (Tractor Supply, Oct 2026) |
OSHA beryllium standard for construction and shipyards (29 CFR 1926.1124 and 1915.1024); Tractor Supply product page for the retail price. Zafa values in brackets come from Zafa’s lab data.
Silica, metals and your crew
Neither glass nor slag is crystalline in structure, so both are far safer to breathe than silica sand. The difference is what else is in the dust.
Coal slag carries trace metals from the coal it came from, and OSHA’s beryllium rule for construction and shipyards was written largely with slag blasting in mind.
Zafa glass is lot-tested for lead and the other RCRA metals, and we publish the results for every grade.
Compare Media Cost per Square Foot
Price per ton tells you little on its own. What matters is what you spend to clean each square foot. Enter your numbers:
Zafa glass
Recycled crushed glass abrasive
Prefilled with the 20/40 price for 4+ FIBC bulk bags.
From your last job, or test with our free sample.
Cost per sq ft
Your current media
The abrasive you use today
From your last job, or test with our free sample.
Cost per sq ft
- Cost per sq ft = (price per lb + disposal per lb) × consumption per sq ft. Leave disposal blank to compare media cost alone.
- Covers abrasive media cost only. Freight, labor, equipment and cleanup are not included, so compare total delivered job cost on the same basis.
- Consumption varies with nozzle size, pressure, surface condition and operator. The surest comparison is a side-by-side test on your own job, and the sample bag is free.
- Lower price per pound does not necessarily mean lower blasting cost per square foot.
- Published prices are not delivered-price guarantees.
Honest trade-offs
What to expect when you switch
- Crushed glass is usually used once. Plan disposal the same way you would for slag.
- Glass is lighter than slag, so the same weight fills more of your pot and covers more surface. Adjust your metering valve after the first few minutes.
- Dry glass blasting can be dusty in open air. Use wet blasting or a dust suppressant where dust control matters.
- Match the grade: 10/20 replaces coarse slag, 20/40 replaces medium slag.
Switching checklist
Switching from slag in four steps
- Pick the matching grade (10/20 for coarse, 20/40 for medium).
- Keep your usual nozzle and start at your normal pressure.
- Open the metering valve less than you would for slag, then adjust.
- Check the profile with replica tape against your coating spec.
Documentation and Traceability
Zafa’s material sourcing and available laboratory documentation should support product-selection decisions. Obtain the current grade-specific technical data sheet, safety data sheet, XRD crystalline-silica result, metals test summary, and any available particle-size/profile results before final specification.
Test it on Your Next Job
Pick up a free bag of the grade that matches your current slag in Lawrenceville. Tell us your grade and we’ll have it ready.