Modifications for Baking Soda
The Air Eraser is essentially an air brush that sprays an abrasive material instead of paint. It's available from several sources including Paasche and Harbor Freight. Out of the box, it's designed to use aluminum oxide and comes with a small bottle of the stuff. Baking soda is much cheaper than aluminum oxide, and less hazardous as well. However, the air eraser needs to be modified to work optimally with baking soda. Many posts on the forum and internet refer to "the baking soda modification", but none actually spelled out what needed to be done. After much digging, I stumbled across a YouTube video that alluded to the changes.
The 3 holes at the base of the media cup need to be enlarged, otherwise they are more likely to get clogged by the fine powder. Unscrew the media cup from the gun and carefully enlarge the holes. The Internet suggests enlarging to about 0.030" (drill #69 or #68). I would suggest starting with about 0.020" first (#76) to see if it helps prevent the initial fill clogging (see below). This will help prevent the baking soda from caking up around the holes and blocking them.
When you press the trigger, air enters the media cup through these holes causing the baking soda to swirl around. It exits the cup at the top, down through the center tube and out to the tip, where another air stream from the small tube in the front shoots it out through the tip. The media flow rate is controlled by the adjustment screw on top of the media cup, which controls the amount of air and media entering the down-tube.
Moisture is your Enemy!
When airbrushing paint, any moisture from the air line that finds its way into the airbrush simply mixes with the paint and ends up on the model. With the air eraser, any moisture in the line will react with the baking soda, potentially clogging your gun with a hard chunk of solidified baking soda. Ensuring a dry air supply is paramount. I had two filters originally, one at the regulator and one inline on the hose to the gun. Apparently that wasn't enough. Searching on Amazon, I came across these small air filters that are designed to attach directly to the gun itself. After adding this filter, I didn't have any more issues. As a bonus, my hand can hold the gun easier, minimizing fatigue.
It was available either individually for around $7, or a 5-pack for $16. I now have 4 spares for available for other brushes!
Simple Clogs
While the tips above won't eliminate clogs, they will certainly reduce them.
I almost always get a clog right after initially filling an empty cup. This appears to be due to the baking soda falling down through the now enlarged holes toward the front air tube. The first trigger press tries to force the whole mess out the tip at once, and usually not successfully. As long as there is baking soda in the bottom of the cup afterward, subsequent refills don't appear to cause the same issue.
To unclog, unscrew the tip (be careful not to lose the O-ring!) and give the trigger a short tap. You should see some baking soda come shooting out the air tube as well as from inside the tip area.
Tap the tip on a hard surface to empty it out. Use a piece of 0.010" wire to ensure the hole itself is unclogged. I always ensure the O-ring stays with the tip when unscrewing it. Otherwise it will most likely end up somewhere in the yard when you tap the trigger (ask me how I know!).
If the gun clogs later during operation, you can try using a piece of 0.010" wire shoved down the hole to unclog the tip. Be careful though. If there is any baking soda in the air tube itself, there's a chance you could push it back and pack it into a clog, especially if there is any moisture in the gun.
It's Clogged Real Good
If you don't feel an solid jet of air from the air tube when the end is removed, or you meet resistance when running the wire down the tube, your air line is probably clogged solid with baking soda. To clean this clog, you need a drill bit and a longer piece of wire.
With the tip removed, use a #77 drill to carefully drill the clogged baking soda out of the air tube. You will probably need to remove the drill several times to clear the flutes as it probably won't self-clear the baking soda. After you have run the drill down as far as it will go, use a piece of wire to ensure the airway is completely clear.
Run the piece of wire down the tube. It should go all the way back to the trigger. If it stops before making it that far, either try to force the wire through the blockage or find a longer drill bit. If you're confident that the blockage is cleared, you can continue blasting away.
If the air tube is still blocked, or you just want to make sure the gun is nice and clean, you can give it a quick vinegar bath. Completely disassemble, including removing the O-rings. If the air tube is still clogged, work the wire into the tube while it's in the vinegar. You'll see the baking soda fizz as it reacts with the vinegar. I also press the trigger while it's submerged to get vinegar up in behind the clog as well.
Don't leave the brush submerged too long, only a few minutes is needed. Immediately afterward, thoroughly rinse the gun, including pressing the trigger to get water up into the air tube. Then immediately hook it up to your air supply and run air through it to blow all the moisture out. Set everything aside to dry.
The Air Eraser does a nice job of removing lettering from painted models. 
Instead of completely stripping the shells, I'm just removing the lettering and plan on spraying over top of the factory base coat. I have one shell where I'm unable to remove any of the window inserts (someone at the factory used an entire bottle of glue on that one car), so paint stripper is definitely not an option.
I've found the Air Eraser to be a nifty gadget to add to the toolbox. It's one of those tools that now I have it, I wonder why I didn't get it sooner. I'm looking forward to discovering other uses for it.
Craig
