Which metals react to sulphur/butyl rubber? 1

[gerkin6000]

Hi all!

Would anyone be able to help advise me about metals that react to sulphur please, or any ingredient used to make rubber?

I'm a jewellery designer using recycled rubber, and have found that the metals I'm using sometimes discolour relativley quickly when in contact with the rubber.

The rubber is bike inner tubes and I suspect its the sulphur in the butyl
rubber which is causing the discolouration.

I've been using silver plated metals and 'gilt' (which i guess is anything thats gold coloured?).

What I've found out so far is that gold should be ok to use. I'm wondering about gold fill, will sulphur react to the % that isn't gold?

I'm looking for silver and gold coloured alternatives. I'm thinking
stainless steel might be a good option? And am also wondering about
rhodium, palladium and platinum? I'm not sure what is more readily available in the form of jewellery chain and findings?

I'd be very grateful for any advice you may be able to offer.

Many thanks in advance.

 

[btrueblood]

Copper and silver will both readily form sulfide compounds (tarnish). Same with tin, lead, zinc and other base metals. Aluminum too, I think. The fact is used to form good bonds between rubber and those metals as the rubber cures. Steel belted tires have copper or brass plating on the steel wires to improve the bonding between tire carcass and wire.

Stainless steels generally won't react with sulfur, and neither will the noble metals (Rh, Pd, Pt, Au). Cobalt, iron, nickel, steel generally won't react very quickly, but sulfur and oxides form compounds that will corrode the metals (add moisture) over time.

 

[unclesyd]

I would stay away from anything with Copper in it.
Silver will blacken under certain conditions when in contact with Sulphur compounds, IE silverware tarnishing.
Your other metals should be OK.

You can buy rubber bands made from rubbers that have no sulphur in them.

 

[gerkin6000]

Thanks dudes!
That really has helped loads, very much appreciated!

 

[EdStainless]

The other thing that you might try is to bake the rubber pieces first. But don't burn or melt them. A lot of the excess sulfur can be reacted this way and minimize issues.

Stainless and precious metals are the way to go.

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