Yes Keri,
It's called "pull through" and it happens when you lay Unleaded enamel over Leaded enamel - the leaded enamel bubbles up and you get some incredible effects.
Hello Keri Lee, You get the same effect if you make at first a layer of flux, then a layer of a very soft enamel and over these one or more layers of harder enamels. You can fire all the shifts at the same time. You can too change between opaque and transparente enamels. Fire a bit longer as usual and with an an higher temperature. You must a bit experimenting which of your enamels works best.
You get a similar effect, if you with "Separation Enamel" working, which you can buy by Thompson enamel. Have a look into the "Note Book 1" in this forum.
Edmund
There is a beautiful speckled technique that an artist I just found Patsy of Ox Art Jewelry uses and I love the look of it! I have no idea how it's done. Can anyone here point me in the right direction? Here's a link so you can see what I am talking about....