Most Stainless has a brushed finish. Seldom the mirror finish of chrome. Take a file or grinder and remove a small area in an area not visible when installed to disclose core material. The chrome finish is not very thick.
How can one know if a floor drain is of stainless steel material or brass with chrome finish. Believe me they almost look alike and I really face difficulty at times while approving floor drains of stainless steel material. Please give some clue, thanks.*
Most Stainless has a brushed finish. Seldom the mirror finish of chrome. Take a file or grinder and remove a small area in an area not visible when installed to disclose core material. The chrome finish is not very thick.
Very few grades of SS are non-magnetic (full Austenitic condition.) I would imagine floor drains would fall into the slightly magnetic (cheaper SS Grades) category so try with a magnet.
Not 100% conclusive but a good start before grinding chrome off or spot drilling the back somewhere. .
Chrome is very hard so a test spot-drill on the back would have a small diameter drill-point running everywhere before starting to drill. Once through the plating, the brass would be then obvious as well.
Also, the chromed items need to be suspended on a rack for the plating process. Usually with Titanium clips so look for some discoloration (yellowing) where the drain has been held (with good electrical contact) while plating the Copper, Nickel and Chrome layers.