Brushed Stainless Steel Door Handles

A recent order prompted a return to the light box to see if we could photograph the luster of brushed rather than polished stainless steel. The lightbox had to be reconstructed to fit the 35” length of the Ergo Epic handle and even then, it was a very tight fit. The Ergo grip was photographed on a golden satin fabric using a Canon ESO Rebel with diffuse light created from overhead rows of LED light cells. The walls of the box are covered in a reflective foil to focus the light on the object and the floor and back wall are usually covered with a black or white backdrop.

How to Brush Stainless Steel

1.     Angle grinder with a blade attachment is used to cut off any gates left from the  casting stage.

2.     Angle grinder using a very coarse grit disk that removes any major surface imperfection. This sometimes will reveal a small crater or void caused by an air bubble that occurred during casting which will need to be filled with steel weld before going further.

3.     A handheld burnisher with an 80 grit sanding drum is next applied to begin buffing and refining the surface.

4.     A second burnisher machine is used with a dual grit scotch-brite sandpaper drum with successively finer grit drums.

5.     The final burnishing is done by hand with scotch-brite pads.

6.     Lastly the piece is passivated.

 Passivation

 316 Stainless steel is known for its rust resistance so what is oxidation and why is passivation necessary? 316 stainless steel is an alloy comprised of iron, chromium, nickel, molybdenum, and carbon. Chromium reacts to oxygen in the air and this oxidation process creates a protective layer on the surface of the stainless steel that acts as a barrier to corrosive forces like salt air. It is the iron component in metal that rusts and while 316 develops a protective coat, during the burnishing process contaminants can attach to the surface. Hence the final stage is to passivate the piece by immersing it  in a bath of citric acid solution which strips any iron contaminants from the surface and bonds with the iron elements to neutralize them and prevent future corrosion.

Marine Grade Door Handles for Beach Properties - Part 1

If you live at the beach or own a yacht you are probably aware of the corrosive effects of salt air and sea water that can eat away at iron causing it to rust and degrade. What causes this to happen and what metals should door handles be made from to avoid this fate?

Our door handles and cabinet pulls are cast either in silicon bronze or 316 stainless steel and both are good choices for ocean or beach environments as they both oxidize in a good way.

To understand corrosion we first need to analyze the alloys that make up stainless steel and bronze.

Stainless Steel

Describes a family of metal alloys the base or main alloy being iron. The other important components are carbon, chromium, nickel and molybdenum and the last 3 make 316 stainless steel corrosion resistant.

Water causes iron to rust by combining with carbon dioxide in the air to produce corrosive carbonic acid which as it dissolves the iron creates a layer of iron oxide or rust.
Stainless steel contains the metal chromium which when exposed to oxygen in the air becomes unstable and combines with the oxygen to produce a thin protective film of chromium oxide. The film is passive and does not harm the metal but forms a tight film that clings to the surface effectively sealing it. The thin layer of chromium oxide adheres to the surface forming an almost impenetrable film that prevents harmful iron oxidation from occurring.

The Nickel component plays a supporting role and it enables the chromium oxide to rebuild and self-heal if it is damaged, it helps the chromium rebind with oxygen to create more protective chromium oxide.

While 304 and 316 grades of stainless steel contain chromium and nickel only 316 contains molybdenum a metal that is particularly effective at preventing corrosion caused by sodium chloride that is present in sea water. The salt content of water speeds up the corrosive effect of carbonic acid and molybdenum seems to slow this process down thereby helping prevent corrosion.

We make our Ergo and Morphic door handles in 316 stainless steel, the alloy is more expensive and harder to machine and finish than other grades but it’s superior corrosion resistance justifies the price tag.