We have received several questions regarding the care and passivation of the stainless steel that virtually every part we sell has an abundance of! While there are several different avenues to reach a final destination, we wanted to recognize some of the newly practiced passivation methods.
Remember that passivating stainless steel is a way of renewing the corrosion resistance performance of the base metal and improving its longevity.
It is designed to both remove small free-iron deposits and restore the passive oxide layer that keeps corrosion at bay. Passivation is done after stainless steel has been completely cleaned with TSP to remove any oils or foreign deposits.
While a relatively concentrated dose of Starsan, which is a blend of phosphoric acid and dodecylbenzenesulfonic acid, or Bar Keeper's Friend (Do not apply to electrically etched markings), which is oxalic acid, does work to passivate stainless steel, there are a few other options that work equally as well.
In fact, many recent studies have suggested that citric acid is an excellent alternative to Starsan or Bar Keeper's Friend for passivation. Citric acid is both easy on the environment and can be more cost effective if frequent passivization is desired.
Lastly, several commercial products have even been introduced to fulfill the needs of passivation for food safe 304/316 stainless, such as Citrisurf. However, citric acid can be purchased in raw form and made into a 10% citric acid/water solution, then heated to 150 degrees for roughly 30 mins to complete the passivation process.