Metal finishing Q&As since 1989
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Zinc chromate plating vs chrome
2004
I am a wire shelving importer. I sell this shelving to the restaurant equipment dealers around the USA. My shelving is plated with zinc-chromate and is used by restaurants for "dry" storage of anything you might have to put on a shelf in a restaurant. Other manufacturers use a chrome plating for the same shelving.
Questions: Which plating finish is more durable or least likely to chip and subsequently corrode? There are would-be customers who refuse to buy my zinc-chromate shelf because they have been told that chrome is a better finish. Is chrome a better finish? Or is it only more expensive? What are the differences between a zinc finish, a zinc-chromate finish and a chrome finish? I currently sell about twenty five 40' containers of this shelving per year. Each container has approx. 3500 shelves of various sizes ranging from 18"x24" to 24"x72".
Your answer would be very helpful to me. Thank you.
NICK BLANEYwire shelving for restaurant applications - LOMITA, California, USA
Chromate is a top coat that is put on zinc plated items to deter the zinc from white rusting. There is no real difference between a zinc finish and a zinc-chromate finish because (although there are now some chromate-free topcoats) zinc plating is always top coated.
Chrome plating is a completely different finish, the steel is nickel plated then chromium plated. Chrome is more attractive in the opinion of most (it is shinier). It is also more expensive.
One of my favorite vignettes, and a totally applicable one for this question, is from Peters and Waterman's "In Search of Excellence", wherein they suggest that restauranteurs who want to offer a quality salad at reasonable price should concentrate their efforts on making sure the lettuce is always fresh rather than hunting for cheap artichokes.
To wit, while the highest quality chrome plating can last decades on a truck bumper in the worst of conditions, it's very easy to do really poor chrome plating that accelerates rusting and deterioration rather than retards it. Because nickel is anodic to steel, if there is a pinhole or porosity, nickel-chrome plating forces steel to rust rapidly. Contrariwise, because zinc offers cathodic protection to steel, it always protects the steel, never hurts it, so it's far more difficult to do a really bad job :-)
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004
I am looking to start importing wire shelving in various finishes & grades (Stainless, Chrome, Chrome Coated, Zinc, & Zinc Coated products) for the hospitality industry, practically for restaurants for cool rooms & dry storage needs.
As I am new to this I would like to know what would be the best finish other than stainless for cool rooms & dry stores? Do transparent paints & powder coats make a difference?
Tristan RitchardShelving Importer - Sydney, NSW, AUSTRALIA
2004
2006
The company that I work for does a few different platings, zinc chromate, nickel chromate, tin, and cadmium.
I'm not too sure on the other metals, but with zinc we always use some form of chromium, there is black hexavalent chrome, yellow trivalent chromate, and clear dichromate.
All 3 give a different appearance to the part that is plated, yellow looks like bronze, the clear looks similar to chrome, and black is a metallic black color.
- Elyria, Ohio
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