Tuesday, February 10, 2009
Tuesday Tips - Nuggets of Darkness, Pearls of Wisdom
Liver of sulphur.
As part of my series on fusing fine silver links, there's a post about patina and liver of sulphur.
What is it?
It's a patina chemical mixture that works on silver, bronze and copper metals. The metal needs to be very clean with any grease or finger oils removed so the patina will take uniformly.
The best way to buy it is usually the dry nugget type, which is added to warm or hot water to dissolve it. Keep even the nugget form very dry and out of the light and air, as it will deteriorate and not have as much power when you mix it up. You can buy it already mixed as a liquid, but it will lose strength much more quickly.
The chemical name is potassium sulfide. It smells like rotten eggs, so use a ventillation fan or take it outdoors. Don't breathe the fumes. You won't want to anyway, this mixture does not smell good at all.
A little bit goes a long way. Sometimes I leave the mixed liver of sulpher at a cool temperature and instead warm the metal before I put it into the solution. When the liver of sulpher solution isn't heated, it doesn't seem to smell quite so much, either.
Rinsing between dipping is important, to get good coverage. It's better to go slowly on how dark you go with the patina. Even if you remove it by tumbling, the metal seems to reclaim the same level of color when you re-apply the liver of sulphur solution.
A weak solution, at a cooler temperature, will sometimes reveal a blue, green, maroon or yellow patina. To preserve the color coat the clean, dry patinaed metal with a clear jeweler's laquer to seal out the air. Otherwise the patina will continue to darken, or may rub off with long wearing and friction.
Don't put wire that already has turquoise stone beads into liver of sulphur, the turquoise often has a lot of copper in the matrix of the stone and liver of sulpher will dull your stone. I don't know of a fix for it, either.
I've also heard that it's not wise to put real pearls into liver of sulpher. It's best if you only put metal into the patina, just a word to the wise, so you don't learn the hard way.
I store my liver of sulphur solution after mixing in a small glass jar (like a baby food jar) with a tight lid, and with no airspace at the top. The air will react with the solution, so fill all the way to the top of the lid and tighten down. I keep it in a dark room out of the sunlight. It lasts a long time for me when stored that way.
It doesn't work well on brass or gold. Most Blick Art Stores will have liver of sulphur, or you can order online from Rio Grande or Volcano Arts suppliers. I have links to both on my sidebar if you need them.