Soda blasting

[Old Guard Dog]

I've been seeing articles on soda blasting, and it seems it would do a great job of removing old paint and possibly bluing without giving the matte finish I wind up with using aluminum oxide. Has anyone used this? Also, will it work in conventional blasting cabinets with regular blasting nozzles?

 

[supercopjason]

I have used it for cars. It will not work with regular equipment and im not sure that it will work for bluing. It is awesome for cars because it wont scratch rubber, glass, chrome or any other surface except paint. Good stuff but not sure if it would work.

 

[Marlin 45 carbine]

have you tryed fine crushed glass at low pressure?

 

[dclevinger]

I've used it in an Air Eraser to clean some rust out of the engraving on a shotgun. It didn't even harm the gold inlays. It is quite a bit more time consuming though. Fine glass beads, like Brownell's has, would be better for general re-finishing. They do give the metal a satin look but nowhere near what alox does.

David

 

[DBR]

I did commercial soda blasting for a while. Here is some info:

Soda blasting removes stuff by "exploding" the soda crystal on the surface and breaking the bond. It works very well for surface coatings like paint - not at all for finishes like plating.

Soda removes loose rust but since it is not very abrasive it doesn't remove the staining. It does not profile the surface at all. It leaves a residue that must be neutralized with a weak acid wash before paint will adhere properly.

Soda requires very dry air in the blast equipment and may not feed well in siphon equipment.

A better choice for casual use would be plastic media. The media must be fine enough to get into the smallest detail that needs cleaning. It is not cheap but it will last a long time.

Here is one source I have used: http://www.tptools.com/p/358,18_Skat-Plus-Plastic-Abrasive.html

With reference to the OP's original question: neither of these methods will remove gun bluing which is essentially rust staining. For that glass beads would be the minimum that may work and fine aluminum oxide "alox" at low pressure will definitely work but will profile the surface and make it rough. Glass beads will also profile the surface but will leave it smooth.

 

[Riss]

I have had good results with glass bead that is used for road striping, as an additive for the paint to make it reflective. It does not seem to have lots of bite when new or when used at low pressure. But then again, I usually wind up turning up the pressure to 20% above cabinet rated pressure. There is walnut media also. Which should be more agressive than the soda and less water sensitive.

 

[DBR]

Walnut blasting media is actually less aggressive than soda. For example, I can remove gel coat from fiber glass with soda but not with walnut. Walnut is somewhat resilient and is used commercially for delicate surfaces like engine parts to remove carbon, dried oil etc.

The closest thing to plastic media is crushed corn cob. The corn cob I have used is made specifically for abrasive blasting and it is very hard.

If you turn up the pressure too much with glass beads the beads will fracture and start to act like fine crushed glass media. This will also leave a profile (roughness) on the surface and ruin the beads.