Grades of 304 are widely used for applications such as food prep benches and kitchen sinks to commercial food processing equipment.
The SS should have been treated at the point of manufacture. I’m not aware of any domestic goods supplier including it in the owners requirements. For some further background on what it involves.
‘https://www.thefabricator.com/thefabricator/article/testingmeasuring/passivation-basics-will-this-stainless-steel-rust-
SS is not immune from corrosion. Chlorides will attack a SS surface. These are found in sea air, table salt, hydrochloride acid and some cleaning products. Hard water can also contribute to staining. IE there are possibilities other than heavy abrasion damaging the protective oxide film on SS.
Noted
As well as being a brushed finish the panel is also laying flat. It will be susceptible to environmental conditions or any thing that may be placed or spilt on it. It’s useful to consider the rust staining may not be due to a product defect.
It can be useful to share which product brand and retailer you have gone back to. It is also important to be taking your issue to one of the retailers managers who has a responsibility for resolving consumer complaints. Several retailers are more often mentioned as being more difficult to get remedy from.
It may be more successful when the retailer is not in agreement to be precise and formal when seeking a remedy. There are numerous other community discussions about the importance of taking a more formal approach when seeking a resolution. You may find these links provided in another recently discussed consumer complaint informative. Quantum Hot Water Heat Pumps - #10 by grahroll
