Summary for stainless steel pittings Discussion
Stainless steel with minor pittings is the focus of this question from a collector of 1960s stainless steel watches who wants to clean the pieces for storage without making the pits worse. Charles Dale says the marks cannot be machined out and asks whether acids, polish, or a rust remover would be safe on likely 304L or other 300-series stainless, especially if the pits may still contain contaminants. He is mainly worried about stopping further corrosion rather than removing the visible defects. The only answer in the thread comes from Goran Budija, who suggests a specific cleaning solution based on an expired U.S. patent: 47.5 g citric acid, 47.5 g sodium gluconate, and 4.9 g tartaric acid in 1–10 liters of water. He says it can be used hot or cold and wishes the asker good luck. The thread does not discuss whether this is the best or safest approach beyond that recommendation.
Q. Hello to all,
I have been researching this site for a long time to find some guide (perhaps even a solution) to my problem. This may sound trivial but I have a small collection of some expensive discontinued stainless steel watches from the 1960’s which have some pitting? to areas that cannot be machined out. They appear to be like very fine fly droppings and on one item like a small speck of fiber from a tissue paper. I know that whatever cleaning method used, these lesions will not go away unless machined but I am more concerned about stopping them from getting worse or spreading, as I know from literature that they do burrow through if left untreated. I want to clean these items to store away as they are collectibles, but am concerned that the pits will get worse if the pits still contain contaminants. Much of my research has suggested nitric acid, citric acid
⇦ on
or
Amazon [affil link] , baking powder, white vinegar
⇦ in bulk on
or
Amazon [affil link] , electropolishing and many other debatable methods. As the stainless steel used is likely to be 304L grade or from the 300 series, I was informed that applying to these sections a cotton bud (to leave for approx. 30 minutes) of some Stop Rust ( consisting of 30% phosphoric acid and TRI-chromate – whatever this means) which is used on ordinary iron should be safe provided that it is then rinsed with demineralised water. I was also advised on a product Autosol stainless steel polish
⇦ on
or
Amazon [affil link]
which consists of aliphatic and aromatic hydrocarbons. I am no expert on metals or finishing? I would be happy to receive some feedback, with many thanks,
Charles Dale
collector of stainless steel watches – Australia
A. Try 47,5 gms citric acid /47,5 gms sodium gluconate/4,9 gms tartaric acid
⇦ on
or
Amazon [affil link] / 1-10 lit water solution. Can be used hot or cold (according to expired USA patent USPT 4,264,418). Hope it helps and good luck!
Goran Budija
– Cerovski vrh Croatia
March 8, 2011