Maintenance & Troubleshooting

Using Sodium Bicarbonate… Read This.

by Comco Sales and Support | December 18, 2023

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The Go-To Abrasive…

Thanks to its particles’ monoclinic shape, sodium bicarbonate easily abrades pliable materials without damaging delicate underlying layers and components. And, sodium bicarbonate is water soluble, which makes for easy post-blasting clean-up.

…That is almost perfect

Sodium bicarbonate comes with one small annoyance: build-up. Most abrasive media gradually erodes a blaster’s mixing chamber, output fittings, nosepiece, and nozzle.

What does build-up look like?

Sodium bicarbonate plating at base of tank in micro-precision sandblaster.

Sodium bicarbonate plating inlet side of 0.060" MicroBlasting nozzle.

Sodium bicarbonate plating inside a 0.046" MicroBlasting nozzle.

Sodium bicarbonate plates at transition points, like: (left: the bottom of MicroBlaster’s mixing chamber; middle: the inlet side of the nozzle (0.060″ pictured) and right: inside the tip of the nozzle (0.046″ pictured).

So, what do you Do?

Keep a close watch on the abrasive mixture exiting the nozzle. Noticeable reduction of abrasive in the air stream is the best indicator that plating is underway.

Particles tend to plate at four transition points inside the blaster. Clean these points thoroughly. Like plaque, build-up attracts build-up. If any residue remains, the rate of build-up increases, shutting down the system again, only quicker.

Build-up Point	Warning Sign	Cleaning Procedure
Tank Orifice (Located at the bottom of the tank)	Decreased to non-existent abrasive flow, but normal air flow.	1. Power down the unit. 2. Remove the tank cover and empty the abrasive into the plastic bag or the storage container. (Keep airtight to prevent moisture from seeping in.) 3. Remove the tank orifice (gunmetal hexagon bolt) at the bottom of the tank using a 1/4" nut driver. 4. Check the orifice with a pin gauge for any signs of obstruction. 5. If the pin gauge meets with resistance, clean the orifice with de-ionized water or vinegar.* (Soak first. Then use mild agitation to completely remove build-up.) 6. Let the orifice completely dry before reinstalling.
Nozzle (Particularly, the inlet side of the nozzle.)	Decreased air AND abrasive flow.	1. Remove the nozzle from the handpiece. 2. Use a pin gauge to check the nozzle ID for any obstruction. 3. If the pin meets resistance, clean the nozzle with de-ionized water or vinegar.* (Soak first. Then use mild agitation to clear every bit away.) 4. Let nozzle dry completely before reinstalling.
PowderGate Output Fitting (Located on the side of Comco's AccuFlo.)	Accelerated wear on the abrasive hose right after the fitting.	1. Power down the unit. 2. Remove the blue quciknut on the side of the AccuFlo and the abrasive tubing that extends from the side of the AccuFlo to the nozzle. 3. Remove the PowderGate output fitting and use a pin gauge to check the ID of the fitting for obstructions. 4. If met with resistance, clean the PowderGate with de-ionized water or vinegar.* (Soak first. Then use mild agitation* until all residue is gone.)* 5. Let the PowderGate dry completely before reinstalling. (Important, as moisture is a killer at this transition point.)
Modulator	Modulator stops humming	1. Power down the unit. 3. Remove the modulator from the unit. 3. Unscrew the modulator housing to gain access to the core of the modulator. 4. Check the core for abrasive particles. 5. If abrasive lingers, use dry-air to blow it out of all modulator components. 6. Re-install.

*Water vs. Vinegar: Water dissolves sodium bicarbonate, but at a slower rate than vinegar.

Alcohol: Alcohol does not dissolve sodium bicarbonate. Submerging in alcohol or using alcohol wipes to clear build-up is an exercise in futility.

Download Sodium Bicarbonate Cleaning guide (PDF)

Don’t Cut the Hose!

All abrasive—including sodium bicarbonate–wears through the hose that connects the handpiece to the blaster

In an attempt to garner full use of the hose, most operators chop off sections where holes develop and reattach the shortened, seemingly good hose. Unfortunately, a visible hole is a red flag that other regions of the hose are thinning. Predicting when these worn spots will erupt is impossible, but Murphy’s Law states that it will happen at the least opportune time.

Reduce downtime (and frustration) by checking the abrasive hose regularly; keeping an extra hose in stock, and replacing the entire hose at the first major sign of wear.

Slight wear is hard to see on abrasive hoses. Make sure you have back-ups. — Even a slight rupture in the abrasive hose leading from your blaster to the handpiece can cause a “White Christmas” in your lab.

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