There is a common misconception about blasting with soda, where people believe it gives a bright finish. This is not so. It is not a popularly used media as it gives a matte finish unlike glass bead and lacks the longevity and aggressiveness of aluminium oxide for example. Blasting soda has larger particle sizes than the baking soda you use at home and can be surprisingly effective.
Dry-blasters find it useful as it is a relatively soft media that breaks apart on impact with a hard surface. It allows them to remove paint, stains and caked-on dirt without destroying the substrate. For them it has the advantage of being environmentally friendly too. A Dana-Ridge wetblast unit has all those qualities built-in to the process already so it doesn’t rely on the properties of the blast media to provide those same advantages.
The main reason bicarbonate of soda is used in a wetblast system, is that it lasts a lot longer in a wet process, is recirculated around inside a cabinet making it less messy than an open system and it readily dissolves in water. It’s this final property that is very useful if you blast complete assemblies because you can wash out the media and protect moving parts where remaining glass bead etc might cause issues.
Removal of the media is achieved by giving the blasted part a wash in a solution of vinegar/water to neutralise the alkaline properties of the soda and prevent crystals forming after it dries. It is important to be very thorough when washing out the media. We then recommend a final rinse in bucket of water and “no rust” solution to prevent any flash rusting.
As you can see from the photos, it cleans the part up a treat and any plastic or rubber is cleaned up by the process too. We will revisit this part in the near future and re-blast it with a fine “AH” grade glass bead to show the difference in finish.
Although soda is a very soft blast media, it is still surprising how well it cleans, especially when fresh. It will blast away surface rust and paint but will struggle with scaly rust however.
You can learn more about blasting with soda here.
The blasting was done in a COMET wetblast machine from Dana-Ridge.