Gentle Giant: Protecting the Substrate While Blasting
For surfaces or substrates that can’t stand up to harsh abrasives, sodium bicarbonate (baking soda) is a highly effective form of blasting media that cleans aggressively without causing damage. Its gentle physical properties make it more forgiving, which means it can compensate for overblasting — or the inexperience of an operator in training.
Watch it work:
Because sodium bicarbonate is soluble, a freshwater rinse after use washes away all blast particles, preventing surface contamination.
The media is also flexible. For example, ARMEX, the original sodium bicarbonate blasting abrasive, can be used in vapor blasting with no modifications to the equipment. Asset owners and specifiers who value the benefits of vapor blasting — less water use, near-elimination of dust, less need for containment — can pair it with ARMEX media to ensure preservation of the substrate.
The sodium bicarbonate is introduced into the vapor blast pressure vessel in the same manner as other abrasives. Lighter in density than most hard abrasives used in vapor blasters, ARMEX requires a slightly larger differential pressure to achieve the desired media flow rate. Because using a vapor blaster eliminates most of the dust created when dry blasting with baking soda — and because the process consumes less media — vapor blasting is considered the most effective and efficient way to use ARMEX blasting media, which cleans:
photo courtesy of church & dwight co., inc.
The media is used on a variety of substrates, including:
the mother of invention
Sodium bicarbonate abrasive blasting originated back in the 1980s during the restoration of the Statue of Liberty. At the planning stage of the project, Church & Dwight Co., Inc., maker of Arm & Hammer baking soda, was contacted by the engineers looking for a way to remove the final two interior coating layers without damaging Lady Liberty's delicate copper skin.
Through trial and error, the engineers tested many different blasting abrasives and discovered that sodium bicarbonate had the desired cleaning and coating-removal properties and did not cause surface damage. Following this success, the company launched ARMEX, the first sodium bicarbonate blasting abrasive.
why it works
Sodium bicarbonate comes in different grades of material, which affects product quality and consistency. ARMEX formulations are manufactured using a consistent process in a controlled environment with the highest grade of sodium bicarbonate.
The media comes in different granule sizes, ranging from 70 to 270 microns. The micron size will determine the degree of aggressiveness of cleaning — with 270 microns providing the most extreme level of cleaning and 70 microns used for lighter, more delicate cleaning.
Sodium bicarbonate is a natural desiccant and loves to absorb water. Flow aids and advance moisture control additives prevent vapor blast equipment from clogging. Without these aids and additives, traditional sodium bicarbonates would clog vapor blast equipment. They also help preserve ARMEX media when stored in high-moisture environments.
Further, these additives have surfactants that help remove heavy grease and oil and prevent surface contamination when re-painting.
Claims or positions expressed by sponsoring authors do not necessarily reflect the views of TPC, PaintSquare or its editors.