Can I combine silver PMC and gold PMC to make a karat gold alloy?
You can combine any proportions of pure silver with pure gold. 14 karat is defined as 14/24s pure gold. If you work out the fraction, this comes to 58.3% gold. 18 karat is 18/24s, or 3/4ths gold. In the case of traditional jewelry, the part of the 14K alloy that is not gold is usually a mix of silver and copper. This blend yields the most yellow "gold-like" color. If the balance is dominantly copper, the result is called rose or pink gold. If the non-gold part is silver, the result is green gold. This is what you'll be making when you combine silver PMC with gold PMC.
    Now, be warned. At the 14K proportions, the result is a pale gold color that not everyone will find appealing (i.e., worth the cost). It is a pale, yellow-green gold, that some would describe as a dull silver. I don't think you want to spend a lot of money to make the silver look dull. At the 18K level, where you mix one-fourth silver to three-fourths gold, the result is a bright, clearly green gold that most people would call dramatic and exotic. In the case of PMC, it is not possible to add in copper because it oxidizes and prevents the clay from fusing.
    As for firing time, for the 14K mix, I'd use the firing schedule of original PMC: two hours at 1650° F (900°C). If you go with the 18K version, raise the temp to 1700° F and stay with the two hour firing time.

Can I fire gold PMC and silver PMC in the same piece?
Yes, there are several ways. Gold PMC is only available in one version, which requires a relatively long firing at a high temperature (2 hours @ 1830°F /1000°C). When the gold is an ornament on a silver piece, simply add it and fire to the maximum silver temperature (1650°F / 900°C) for two hours. The gold will not be at full strength, but in this use it doesn't need much structural strength.
    A second option is to create the gold element and fire as recommended: 1830°F (1000°C). When the gold is cool, build the silver element directly on it. Allow to dry and fire for two hours at 1650°F (900°C).

How do I use Aura 22?
Note: A detailed instruction page can be downloaded from the Technical Data and Charts page of the "Getting Started" section of this site.
Aura 22 can be used on any version of PMC. Fire the piece, then apply the gold layer. It's important that the silver is absolutely clean. This is the case when the silver comes from the kiln--don't tumble it or handle it any more than you need to. If a piece has been handled or polished, put it back in a firing to clean it.
    Paint on a layer of Aura 22 and allow it to dry. If the Aura has dried out, add a drop or two of media, but be conservative with it. Allow a few minutes for the media to dissolve into the gold, then stir well. Remember that every bit of media you add dilutes the gold and undermines your efforts. Paint on a second layer and allow this to dry.

HOTPLATE METHOD

Set the work on a hotplate turned to High. Allow the silver to heat to the point where a bit of wood chars--this indicates the proper temperature. Turn the hotplate down to medium and lightly press the Aura 22 down onto the silver. The purpose here is to make a perfectly air-tight bond between the silver and the gold. When this is achieved the two metals will instantly join.

TORCH METHOD

Warm the piece slowly. You will see some smoke and then a momentary flame as the media burns away. Continue heating the entire piece with a soft flame until you see the gold layer shift from brown to a mustard yellow. The silver will be at a very dull red, visible only in a darkened room.

KILN METHOD

Place the piece in a kiln and bring the temperature up to 800°F (425°). Allow it to sit at this temperature for about five minutes, then cool and burnish.

Can I make a gold wash by mixing PMC gold with water?
How do I use it?
Mix a pinch of gold PMC with either pure water or alcohol. I've had good results with both. Make a smooth creamy solution and paint this onto a clean, fired PMC silver . Allow it to dry. You will need to apply two or three layers--a single layer is pale and looks more like tarnish than gold. This is where alcohol helps because it shortens the drying time, but depending on climate, you can make a layer dry in a few minutes. I swing my desk lamp down close to the work to speed up the drying.
    I've had successful results with both torch and kiln firing, though again I want to emphasize that experiments are on-going. In the case of the torch, heat until the gold changes color... this is difficult to describe but clear after a few attempts. The gold layer will be brown when applied. Under the torch there is a moment when it shifts to a uniform matte yellow. Stop there. In the kiln, bring the work up to 1400° F (760° C) and hold it for a minute or two.
    In both cases, the result will be a yellow-brown matte color. The gold can be burnished by hand or in a tumbler. We've had some cases where small bits flaked off, in which case, you can repaint the spot and repeat the process.