Sodium bicarbonate, otherwise known as baking soda, is a familiar age-old product that has been around for generations. There is probably an open box of sodium bicarbonate sitting in your refrigerator right now. We use it to clean our teeth, cure hangovers and upset stomachs, cook our bread, put out fires, clean battery cables and now strip our cars to bare metal.
Remember the big hullabaloo in the 1980s about the restoration of the Statue of Liberty? Well, it was during the restoration process of Lady Liberty that sodium bicarbonate was first pioneered as a blasting agent. If baking soda was good enough to clean Lady Liberty's drawers, it's good enough to clean our cars right?
While at the '06 Grand National Roadster show in Pomona, California, we came across an informative display booth set up by a company called Anacapa Soda Blasting. Anacapa Soda Blasting has one of the larger, more sophisticated blasting booths in California. It also had several different vehicle panels on display that were media blasted. Some panels were blasted using sand while others were blasted with sodium bicarbonate. When compared side by side, the sand blasted metal substrate was not only visually different, but there was a texture difference as well. The traditional technique of sand blasting can be harmful to the substrate on which it is being used.
Sandblasting is highly abrasive and leaves a "signature" on the substrates surface; it can reduce the metal's density as well as building up heat. Heat build up can result in potential sheetmetal warping. A vehicle that has been sandblasted can also have potential problems in the paint booth as well. Just ask any painter; many of them will relate stories of the difficulty in removing sand from the cracks and crevices in a vehicle prior to painting. So, what are the advantages to using this alternate method?
Environment: The environmental factor for the shop and employees where sodium bicarbonate is being used is the biggest plus. When sand blasting, crystalline silica is present in the air. When crystalline silica is inhaled over time it can cause a respiratory disease known as silicosis, which is almost always fatal. Sodium bicarbonate is non-toxic and presents no such hazards. Still it is recommended to wear a respirator of some type when using sodium bicarbonate or any air borne particles.
Substrate protection: When using sodium bicarbonate on a vehicle, it will remove paint and light rust, while leaving no heat build up and signature on the metal. Sodium bicarbonate will not affect glass, rubber, chrome or stainless trim parts in an adverse manner. However when doing a full restoration, these parts are usually removed before blasting anyway.
Water Soluble: Unlike sandblasting, where the metal substrate needs to be painted immediately, sodium bicarbonate is non-abrasive and does not affect the surface tension of the metal. After blasting with sodium bicarbonate, a vehicle's surface can be left bare without fear of flash rusting for a few weeks after the fact. In order to neutralize the remnants of the bicarbonate on the metal, it is recommended to thoroughly rinse the vehicle down with a water/vinegar mix; however the use of vinegar can lead to flash rusting. We were told that rinsing the vehicle with water then using an auto body metal preparation solvent will work just as well.
What are the disadvantages?
Rust Removal: While sodium bicarbonate will remove paint, primer and light rust, it will not remove heavy rust and plastic body filler. A good old fashioned can of elbow grease or a dual action sander is better suited to removing filler and heavy rust.
We're not here to dissuade you from using other methods of media blasting your vehicle; we simply want to present another option when it comes to the restoration of your classic car. Anacapa Blasting invited Super Chevy for a visit to its facility in Oxnard, California. While there, Manny Vega, the owner of Anacapa, invited this author to suit up and blast a vehicle in the booth-we gave it the old college try.