Spent abrasive is like used coffee grounds

Spent abrasive is like used coffee grounds.

Resources are precious. Like most of our readers, I’m sure you like the challenge of determining how to get the most mileage out of your tools and supplies. But recycling abrasive collected from your dust collector is inefficient, cost prohibitive and depending on your part, dangerous. Here’s why…

Think of using spent abrasive like trying to make a second pot of coffee with used grounds. To the naked eye, used grounds may look fresh, dark and dry enough to yield another pot. But a second past will likely produce a watered-down coffee-like liquid that delivers a fraction of the caffeine needed to get you through the next staff meeting.

Like coffee, micro-abrasives are most effective fresh.


90% of Micro-Abrasive Hits the Target

MicroBlasting is different from cabinet and grit blasting. Ninety percent of abrasive propelled from a MicroBlaster’s nozzle hits the intended target; whereas ninety percent of abrasive from a cabinet or grit blaster usually misses the target. Most micro-abrasive does its job in a single pass.

A quick glance at the nozzle orifices below illustrates why. Look at the extreme focus the MicroBlasting nozzle on the far left provides.

nozzle size comparison: microblasting (L) vs. traditional grit (R)

The abrasive stream of a MicroBlasting nozzle (L) is much more focused and precise than traditional cabinet or grit blasting nozzles (R).


Particle Breakdown

Every time an abrasive particle hits its intended target, the particle changes properties. The particle breaks down, decreases in size, dulls or sharpens—depending on its chemical and physical characteristics. For instance, glass bead, which has a round shape and is used to peen surfaces, shatters into crushed glass shards after impact. Shards do not peen. Shards leave gashes. (We told you it could be dangerous.)

Most micro-abrasives break down into finer dust after impact. As you can see below, sodium bicarbonate deteriorates quite a bit. Want to use that spent sodium bicarb pictured at right? Then, you will need to dial in your process again, set aside more time to blast and use twice as much abrasive to get the desired results. And still, the resulting surface may not meet requirements.

sodium bicarbonate particles before & after blasting.

Sodium bicarbonate granules before blasting (L) and after blasting (R).

CHART: sodium bicarbonate distribution density before and after blasting

Sodium bicarbonate distribution density before (RED) and after (BLUE) blasting. CLICK TO ENLARGE.



Spent abrasive is not the only material collecting in your dust collector. Bits of coating, residue and surface material removed from your part funnels down there, too, along with dust from other processes in your shop, clothing fibers, stray hair and other foreign small particles found floating through the air. Introduce these contaminants to your blasting process, and risk clogging the blaster’s small nozzle, or worse, damaging your part.


More Parts in Less Time with Less Abrasive = Better Coffee

Again, 90% of abrasive from a micro-abrasive blaster hits the target. That means almost all of the abrasive particles are fully used in a single pass. Which means (here us out):

  • you can process more parts in the time allotted,
  • and that helps you meet your deadline earlier,
  • which, consequently, frees you up to go get really good cup of coffee before the next staff meeting.*

*Comco does not endorse a specific brand of coffee or a specific coffee shop. But we do champion staff meeting survival tools and tactics.


Is a job shop making or processing your parts? Request “fresh abrasive” in your spec to get the right tolerance. Job shops tend to be more familiar with cabinet or grit blasting and less aware of the dangers of recycled micro-abrasives.


Dig Deeper


Pat B, Sales and Marketing Manager

Questions about abrasive?

Email me or give me a call at 800-796-6626.