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Prevent Stainless Steel Tarnish During Vulcanization

We manufacture stainless steel braided hose. We are experiencing tarnish to the stainless steel outer braid during our vulcanization process. Steam cure at 310 F. What solution or dip can I apply to the hose before vulcanization to prevent the stainless steel from tarnishing?

Clem Suther
Sr. Development Engineer - Manhattan, Kansas, USA
2003

2003

It rather sounds like you might be getting some discoloration from the sulfur or other curing agents in the vulcanization process. Coating the stainless steel before vulcanization may or may not help you. If it is volatiles coming out of the rubber and depositing on the steel it will not help to coat it probably. The other problem with coating is that most coatings will eventually start to come off and then you have a mess. If you choose to coat it, make sure that the coating is very durable long term, and the coating itself will not discolor in the process.

Is it possible to treat the hose after vulcanization to remove it? If you send us a piece we can determine what is on the surface and how to get it off post-vulcanization.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2004

I have had some success pre-treating the stainless steel by cleaning it, followed by a chrome containing product"Iridite 14-2" (Use 1 1/4 oz/gal. room temp. 3 minutes)a product designed for treatment of aluminum. However this product will passivate the stainless and leave a thin film of nickel chromate and oxides that may give some protection from sulfur and other reactive materials in the vulcanizing material. An alternate is "Chemidize 727ND" (use as is)a product designed to clean and oxidize stainless steel and Aluminum. I have tried non- proprietary chrome treatments without success. Sorry for the commercial products named. They are available from Macdermid from Waterbury CT

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])

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