‘Soda Blasting’ is used to describe the process of using sodium bicarbonate (baking soda) as a blasting medium. There are many ways this can be achieved and I will try to explain the basics.
What is Bicarbonate of Soda?
Bi-carb, Bicarbonate of Soda or Sodium Bicarbonate is classified as a salt with a chemical formula of NaHCO₃.
As a salt, in water, it separates into sodium ions and bicarbonate ions. Bi-carb used in wet abrasive blasting has been treated to slow down the rate at which it dissolves.
Baking soda in water is alkaline with a pH of about 8.3.
Brief Soda Blasting History
In the mid-’80s, as part of the 100th-anniversary celebrations, the Statue Of Liberty was given a full makeover and repair. The internal steel structure and copper surfaces were all cleaned and re-coated.
Many different methods were used to achieve the required removal of old coatings on the steel structure. However, when it came to the copper skin, only a delicate touch would be suitable. With many experts involved in the project, it was identified that using bicarbonate of soda through an abrasive blaster would perform best.
A commercial-grade bicarbonate of soda (baking soda) was manufactured and donated by Arm & Hammer. It was abrasive enough to remove the green oxidisation however, gentle enough to complete all the copper surfaces.
With such a high-priority job using this ‘new’ media, it quickly became popular for many other applications.
The good
Many new applications for soda blasting were quickly found. Where low to minimal impact on the substrate was required, soda seemed to be the way. Cleaning glass, stainless steel, and aluminium were suddenly possible without making the slightest mark on the surface. The use of basic abrasive blasting units was commonplace but the flow characteristics of soda and sand are quite different. Vibrating bearings and other mechanical means were all tried with varying amounts of success. Technology and design quickly advanced to more efficient machines of today.
Baking soda has less impact on the environment when compared to chemical treatments. Bicarbonate Soda is a food-grade cleaner that is suitable for most food preparation equipment. Soda blasting is a common cleaning practice for commercial kitchens, production equipment, mixing vats and ovens. Soda blasting is also, less aggressive than other blasting media. This is great for engine parts, brass and surfaces that shouldn’t be pitted by the blast media in any way.
The bad
As a ‘safe’ blasting medium, Bi-carb has a negative side. Bicarbonate of Soda makes a great weed killer. Bicarbonate ions are found in all living systems and easily convert to CO2 and water. Sodium is an essential plant nutrient in tiny amounts. It can greatly harm or even kill them because too much sodium is toxic to plants. Any plants that it touches will potentially turn yellow and take several weeks or months to recover. Soda blasting must be contained so landscapes and gardens are not affected. Garden Myths has a good article explaining more about Baking Soda in the garden.
And the dusty
Something obvious to anyone dealing with soda blasting… the dust! Even with wet abrasive blasting, there is still quite a drift of Bi-carb from the blast area.
It certainly has a place as a beneficial medium for certain jobs and applications. Many people are either for or against Soda Blasting. Here at MP BLAST, we recognise that there is a place for soda blasting. If the application calls for soda blasting, use it!