Enamels on Different Metals-What A Difference.
What a difference in the brilliance of the color. You can use foils to your advantage to get the enhanced color you are looking for. Gold foil makes colors have more yellow. Copper will warm colors up. Silver will make the true color and sparkle.
You can add foil anywhere in your jewel. If your base plate is copper add a small amount of silver foil to make a little sparkle with your favorite color of enamel.
A question came up today about when to use hard, medium, and low firing enamels.
Hard firing enamels are fired at a higher temperature as in the 1500’s degree range or longer in the kiln.
Medium firing enamels I think of using in 1400’s degree range, or at higher temp as 1500 degrees, but less time.
Low firing enamels maybe fired in the 1300’s or even in the 1400’s with less time.
The purpose of all this is to balance two things.
First the expansion of the metal being used.
Second your technique being used.
Starting with copper as it is used most commonly in enamels.
Copper oxidizes the fastest of the metals we use in enameling. We balance this by using medium firing enamels so they melt or fuse before the copper has time to oxide. And using higher temperatures. If it oxidizes the enamel is likely to flake off or just discolor, but many enameling on copper use the oxidation to get some beautiful colors.
Another way to balance this is to use finer grit of enamel. The finer grit will fuse quicker than a larger grit of enamel without allowing oxygen to get to the copper. Without oxidation the enamelist achieves that beautiful gold or stunning golden orange copper color.
It is best to know the fusing points of all your enamels not only so you know which ones to apply as a base coat of enamel known as flux, which should be the hardest enamel, to avoid the lower layer to rise above the secondary layers as seen below.
Low firing enamels vs high firing enamels
Above the flux was a lower firing enamel than the top coats. So as the top layers melted the flux rose up along the edges and the top layer of enamel puddled in the center.
2) Same here,
Low firing enamels vs hard firing enamels
In this next image flux coat of enamel was not hard enough to prevent the following layers of enamel from touching the sliver. And the brownish color of enamel is burning.
In cloisonné we never want our warm colors to touch the silver. It causes burning. Silver is going to hold heat longer than copper so we use a hard firing base. And in some incidences we will use several layers of the hard firing flux before layering in our warm colors to be very sure the red never touches the silver base.
Along the wall of the fine silver cloison wires I will put a fine line of blue to keep any warm color from burning.
Enamel burning along the cloison wires.
A comment to address
“I’m torch-firing, I always have my work in my sight so I just watch for signs of melting, which happens very fast. I’ve had “pull through” with Titanium White. Titanium White really reacts nicely with copper and you can get some really lovely, but unpredictable, effects. With a little over firing the enamel turns a beautiful rust color and in spots will be green.”
Yes these effects can be used to your advantage, this is the oxidation of the copper coming through. And in torch firing I realize you are not going by temperature and have the advantage of seeing all that is happening.
Enameling on copper, as in painting enamel in this piece,
When you need hard firing enamels
It is necessary to use a hard firing enamel = flux as it will be fired many times and I do not want the painting to disappear into the base coat of flux. Also in repeated firings the copper can still oxidize through the enamel and show a color change after many firings. As I paint my image I need the painting enamel to adhere to the base coat of flux by firing the piece, then I can continue layering my painting with enamel colors (soft firing enamel) that fire at a lower temperature or less time. The domed metal add strength or less expansion. So it can handle a harder firing enamel without so much expansion or movement in the enamel. If the base coat was a lower firing enamel it would become soft enough in firing the image would distort as the enamel base or flux would move before the image enamels fuse. Painting enamels are a soft or low firing enamel= as they are ground to a face powder grit.
Make color plates
The enamel dot fourth from the left is still grainy after all the rest are fused. If you have three enamel on a plate, one hard firing, one medium firing, one low firing and fire the plate once, you will see they melt at different speeds.
If you want to use them all in one project just remember the hard is on the bottom then the medium and then the low firing enamel. This is also why you can use unleaded with leaded enamels as long as you put the unleaded on the bottom as it is a high fire enamel.
A couple of things tiny bubbles in enamels can be from,
First the addition of Klye-fire. I do my best not to use this but I realize in some designs we need it. The last time I used Klyre-fire, a mixture of 1-5 parts distilled water was best. It helps on a 3d surface but I could still see a few tiny bubbles. Klyre-Fire is very helpful on plique a jour. But you do see time bubbles.
Second way you can get those frustrating tiny Bubbles in enamels can be from sterling silver that has not been depleted properly. The more you fire the worse they get.*(
And last that I have seen, specks that usually come from old or deteriorating enamels. When you wash them you see tiny white specks in the container. On your first few firing you will see some are white in your enamel, then continue firing some look like beige-brown goo, and sometimes they turn into bubbles.
There are several reasons you could have cracking in your enamels and here are a couple of ideas of how to avoid cracking enamels
The most common reason enamels crack is there is not enough counter enamel on the jewel. Counter enamel is enamel on the back side of the jewel. Your base metal expands as well as the enamel when heated, and contracts when cooled. Without enamel on both sides of your base metal one side is going to expand more causing the opposite side to crack. If enamel is placed evenly on both sides of the metal you can eliminate this cracking. Sometimes this happens as it is cooling, when this happens there is very little enamel on the back. But I have seen the enamel crack years later when the enamel was not even on both sides of the base metal.
In some cases you can also dome a piece of metal and use less counter enamel as in a bead. But if you plan to put a thick layer of enamel on the front of the metal you then need more counter to avoid cracking in your enamels.
Another reason and how to avoid cracking enamels is if you use a hard firing enamel next to a low firing enamel. Hard firing enamels take longer to fire, and low firing enamels take less time to fire. Great reason the make test plates and see when each enamel melts first when they are all fired at the same time on the same plate. You can see on my test plate dot #4 is still grainy while the others are smooth. So #4 is a harder firing enamel and if placed next to #5 and you fired it long enough that both enamels were smooth in time the jewel will crack.
Cracking takes place in leaded enamels as well as unleaded enamels. Unleaded enamels are harder firing enamels than leaded enamels so if you combine them on the same jewel you can experience cracking. If you need to use them together use the unleaded first then layers of leaded to avoid cracking.