I need a black patina (very black) on silver that has keum boo gold decoration. LOS doesn’t seen very ‘black’ and apparently tarnishes the gold. I can’t buy Black Max , what else can I use please?
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Since no one else has responded, I’ll take a try. Full disclosure I haven’t done a lot of Keum Boo, but I have done a lot of gold overlay onto sterling silver and then oxidized the silver.
I’m sure you know this, but to make sure, all patinas are a chemical reaction building up an oxide coat on the metal. In the case of LOS, Black Max or whatever on silver, the metal should be surgically clean first. The way to test if the metal is clean is to apply a drop of water onto the silver. If it’s dirty, the water will ball up. If it’s clean it will spread out evenly across the surface. My favorite way to clean metal before a patina is to use a fine abrasive cleanser and tooth brush, like Ajax or Comet. There’s lots of other options though if you don’t want to scrub your metal with a fine abrasive cleanser. The main thing is that if water balls up on the surface it’s dirty. If it spreads evenly across the surface it’s clean.
Fine silver is fairly inert. 24 kt gold is inert. That means your 24 kt gold overlay shouldn’t react to LOS. (In your case, the 24 kt gold probably is reacting to the LOS because the gold merged with the silver during the fusing process.) Also because you’ve built up layers of fine silver onto sterling before fusing the gold, it’s going to be harder to oxidize the silver than it would be if it were pure sterling (silver and copper).
As far as I know oxidized silver never turns black. (including with Black Max) It turns into varying shades of gray. Some darker than others.
To accelerate LOS action put about small grape size crystal into a 1/4-1/2 cup of hot water, let it dissolve completely. LOS works best on silver when it’s hot. Also because you’re building up an oxide coat, it’s generally best to do a series of successive quick dips and water rinses to build up the oxide coat slowly.
One of the big mistakes with oxidized silver is building up too much oxidation, too fast, because then it flakes off.
If you’re having a hard time keeping the gold from oxidizing too, you can apply a resist on the gold. Two of my favorites for this are nail polish. You can remove it after oxidizing with nail polish remover. Another is rubber cement. What’s great about rubber cement is that it’s easy to remove.
LOS crystals are notorious for deteriorating due to exposure to oxygen, light or moisture. These days I’ve switched over to the LOS gel because it’s easier to keep fresh. Follow the instructions on the container for LOS gel.
Since it sounds like you have LOS, I wouldn’t give up on it yet.
Let’s see if others have advice as well.
Best of luck!!
Jeff
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I forgot to mention, another of my favorite ways to clean metal before patinas is a soft brass brush and dish soap.
Cheers!
Jeff
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As Jeff has mentioned, LOS creates a beautiful gunmetal grey on silver. It’s my understanding that Gosiba, which is sold by Allcraft, will produce a black finish. Hopefully others will chime in here.
It’s been my experience that most commercial keum boo gold foils will appear to tarnish slightly after LOS. Although gold should not take on a patina, I believe this may occur because the foil is so thin/porous or that the gold and silver are swapping electrons? If my gold pattern isn’t intricate I’ll use Dykem blue plotting fluid and a fine brush to cover the gold, which acts as a resist and is easily removed with denatured alcohol. You could also try burnishing the gold again after application.
Hope this is helpful.
Keep us posted.
Pam
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For a black black patina - first do what Jeff has described - get the metal surgically clean. The patina will look blacker if the metal has a tooth - either from ajax or right out of the abrasive tumbler or with a red 3M bristle brush. If you are doing the manual “toothing”, be sure to get right next to bezels, overlays, etc.
My best mixture is a pinch of iodized table salt, about a tablespoon of household ammonia, 8 to 12 oz room temp tap water (not hotter than 101F) and a half teaspoon of LOS gel. If you are using dry, try it first in room temp water and see if it stinks and is a dark yellow or gold.
Do not touch the surface of the silver with your fingers. Put your piece in the well stirred mixture for a couple of minutes, then remove and using an old clean tooth brush, scrub the piece to make bubbles. Repeat, even several times. If it still isn’t dark enough, dip the piece in warm water, like the coffee you drink warm, and repeat the earlier process. Rinse in cold water. Let it dry naturally.
This is what I’ve used for 30+ years, sounds like black (bad pun) magic.
Judy H
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We use Birchwood Casey Aluminum Black on silver. You don’t get the rainbow colors, but pretty black. Its a warm black. Nothing is truly black except paint, enamel or Black Max.
Ruthanne Robertson
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LOS is basically sulfur tarnish. LOS is potassium sulfide and potassium polysulfide…which when in solution, it provides sulfide ions that react with silver to make silver sulfide, which IS tarnish… I was able to get a jet black patina by following the steps to prepare the silver as many have stated previously… the silver should be very clean. I used a small, thin artist’s paint brush to apply the LOS solution, being careful not to apply it to areas you don’t want to tarnish… the metal turns golden brown initially, then darkens. To get it darker, I let it dry a little, as slight drying concentrates the residual LOS, but not completely dry, and repainted more LOS until the jet black color was achieved. Doing it slowly, in steps lets the LOS penetrate and sucessively makes more black silver sulfide tarnish…if the tarnish gets too thick, it will flake…If there’s gold on top the silver, especially low karat, it will tarnish also but far less than the silver… to stop the reaction once you’ve achieved what you want, wash it in running water from the sink tap until it’s clean and all of the LOS has been washed off… the patina will be thick enough to polish gently using a buffing wheel without any polishing compound…the buffing wheel cannot be used on anything else, as residual sulfide will tarnish what ever else you polish… The best way to practice is to use a piece of silver scrap and apply LOS… continue experimenting until you get the desired result, before applying it to your jewerly. Keum boo should not tarnish much if at all, especially if it’s 24k gold… gold content in Keum boo varies between 23k and 24k…