Firing Enamels
Selecting an Enameling Kiln
The kiln should be programmable to at least 1600°F / 871°C. The door should open to the side (front loading) rather than a top loading type. a top-loading kiln is less safe, makes this process cumbersome and can lead to spilled enamel powder, dropped hot pieces, or a delay in removing the fired piece fast enough. Make sure that you can quickly and easily insert and remove your enamel pieces. The kiln door should have a window. A window will ensure that you can keep an eye on the piece during firing. This will help prevent over or under firing.
Making Samples
Powdered enamels don't always mimic the fired version or even the sample on the website. Making a sample of each color you are using will help you pick out the perfect color or combination of colors. Many experienced enamelists use copper pennies (pre 1980). Punch a hole for display and clean using the standard methods for enameling, making sure to counter enamel the back.
Opaques - fire two layers
Transparents - first fire an undercoat of white and then fire a coat of transparent.
Label each sample with the appropriate number for easy reference.
Foils
Enameling foils are often used for special effects in enameling. Gold and silver foil are the most commonly used. Often they are used to add more brilliance to the transparent enamel overcoat or to prevent unfavorable metal/enamel reactions. Fire at the temperature needed by the enamels underneath for 2 to 3 minutes. The lower temperature will result in more “crinkly” foil and the higher temperature in smoother looking foil. 23K gold foil and leaf turn darker when fired but this can be remedied by covering them with a transparent enamel and re-firing. Enameling over silver and 23K foil will keep them from tarnishing.
Steps for Kiln Firing
Before firing pieces, pre-heat your kiln to 1400°F - 1450°F / 815°C. If your kiln includes user-defined programming, set the hold time for 6-8 hours to ensure enough working time so the kiln won’t shut off in the middle of a project.
While the kiln is heating, prepare your metal. In order for enamel to have permanent adhesion, the metal must be cleaned properly. Doing so prevents the enamel from cracking or popping off the surface during cooling. Once clean, don’t touch the surface of the metal. Apply the first layer of your design. Then, transfer your piece to the steel mesh firing rack and/or trivet to be fired and dry completely. Using the top of a warm kiln will speed this process.
Wearing kiln safety glasses and a heat resistant glove, use a steel firing fork or spatula to place the firing rack in the center of the kiln as quickly as possible and carefully close the door. Doing this quickly will prevent the kiln temperature from dropping. You can set a timer for 2 minutes as a guideline only. Experience will teach you how to recognize the different texture stages so you do not under or over fire your pieces.
When the piece has fired to the correct texture, (again, wearing your safety equipment) use your steel fork or spatula to remove the firing rack from the kiln; set it on a heat protected surface, and let the piece cool down slowly.
Firing time can be as short as one minute or as long as five minutes, depending on the technique being used or the size of the work and thickness of the metal. In general, Thompson Enamel suggests firing only to a gloss. On average, this would be between 1-1/2 minutes to 2 minutes. Given times and temperatures are intended as a guide to start with. You may have to adjust up or down for the above reasons.
The three stages of firing (at 1450°F) are wet sugar (about 40 to 45 seconds)then orange peel (about 55 seconds to 1 minute) and then full gloss (1-1/2 to 2 minutes).
When firing enamels in a kiln you will need a firing fork, a firing rack and an appropriate trivet. A kiln shelf is recommended for the floor of the furnace to catch any spills of enamel that may occur. Make sure to use appropriate gloves when working with the kiln.
Steps for Torch Firing
As you begin with enamels, you might decide you’d first like to try working with a torch before investing in a kiln. You can use just about any type of torch to fuse enamel to your metal pieces, but a butane torch is best for small pieces.
Make sure to work on a heatproof work surface when torch firing your enamel pieces. This way, if any of the hot glass slides off of the piece, it will not create a fire hazard.
Just like kiln firing, use all the appropriate safety equipment when torch-firing enamels. In addition to safety glasses and heat resistant gloves, you should also use a face mask specifically approved for enameling, especially if working with lead-based enamels. Finally, be sure to work in a well-ventilated area, whether you’re working with leaded or non-leaded enamels. Keep in mind that non-leaded enamels are much safer for torch firing. Now that your firing area is set up, prep your metal and add the first layer. Place your prepared piece on a trivet. Then, set the trivet on the mesh firing screen that is resting on your tripod. Make sure that the enamel is completely dry before torch firing. Now you’re ready to light your torch and start firing. The torch flame should be underneath the mesh firing screen. Begin to move the torch in an even, gentle, circular motion. As the piece heats up, you will start to see the various stages the enamel goes through (sugar, orange peel and then gloss). When you’ve reached the desired stage, move the flame away from your piece and turn off the torch. At this point, let your newly fired piece cool down. Once cool, you can either add another layer of enamel to fire, or if the piece is completed, prepare for finishing.
Even if you plan to do all of your enameling in a kiln, take the time to practice firing some pieces with a torch. This practice will help you become familiar with the sugar-coat stage, the orange-peel stage, and the fully-fused stage and it’ll help you recognize a piece that is over fired.
The trick is to have a hot enough torch for the size and thickness of the piece being fired. With mapp or propane gas, copper tooling foil, malleable copper, or 24 gauge copper works best. If thicker and larger copper pieces are to be torch fired, a hotter flame may be needed.
Sunshine Enamel
Sunshine Enamels are sensitive to high heat. Ensuring the kiln temperature is accurate is important. Sunshine enamel can be applied like a watercolor, acrylic, or oil. Use individually, or mix colors to increase your color palette. Simply use a small amount enamel in a water color tray and add a few drops of distilled water. Mix with a small brush. Add more water is needed. Consistency will be thin. Apply one thin coat at a time. If a more intense color is desired, apply a light dusting of flux to cover the dry, unfired sunshine enamel and fire. Repeat this process until the correct depth of color is achieved. Adding one thick coat will result in bubbling. Always apply a dry flux coat for all firing applications. We do not recommend torch firing Sunshine Enamel as they may disappear if the heat becomes too high which is difficult to control with a torch.
Kiln Fire approximately 2 - 3 minutes at 1300°F / 704°C - 1350°F / 732°C.
Note: After application, let dry and then sift a light, dry coat of Thompson flux or Ferro coating flux, coating piece completely. This will help preserve the color integrity of Sunshine Enamels.
