Prometheus ® Bronze Clay (NL)
Working with Prometheus ® Bronze Clay is similar to working with silver clay, polymer clay, modeling dough, bread dough and ceramic clay. It is very easy to use.
With normal consistency, Prometheus ® Bronze Clay does not stick to the hands or plastic work surfaces. However, oiling your fingers and the work surface is useful, and is not harmful to your clay. Olive oil is preferred.
Remove the clay from the plastic package and place it on a clean plastic surface or waxed paper. Use your fingers, roller, spatulas, clay shapers, artisan knives, toothpicks and other simple tools to shape it, texture it, or put it on a potter's wheel. You can create texture in the clay with stamps, texture mats, leaves, paper, and other interesting textures.
When you work with the clay from the package, we call this "The Wet phase". Try not to work too long at this stage, because your clay dries in the air, but don't rush, Prometheus ® Bronze Clay gives you enough time to play. However, if you detect any cracks on the surface, immediately treat or spray the clay with water, and fill the cracks with a little paste to repair them.
You connect two pieces by making the points that will touch each other wet, or add a little paste (you make pasta by mixing a little clay with a little water until it has the thickness of thick yogurt). When the two pieces are dried, wet the points that touch and stick with paste to create a secure connection.
Keep all unused clay in a plastic bag with a zipper to prevent it from drying out. Place cut remains immediately in the bag while you work, and keep it closed.
If you do not intend to work with the clay for a while, put the sealed plastic bag in a jar with a tight-fitting lid. Placing a wet sponge on the bottom of the pot will keep your clay in good condition until your next use. Keep the sponge moist and add water if necessary.
Before firing the bronze clay, you must dry it completely. This can be done with a hair dryer on the top of your fire kiln or in a household oven at 100 degrees. Hot plates or food dehydrators also work well.
To check whether the clay is thoroughly dry, place the warm clay (directly from drying) on a cold mirror. After 10-20 seconds, move the clay and check that no condensation remains on the mirror. This test is especially important for large and thick parts. If the piece is not completely dried, then it can crack, break or bubble on the surface during firing.
We do not recommend fast drying for large pieces, as it can lead to cracks. For this it is recommended to let the clay dry for a few hours at room temperature and then dry at a moderate temperature.
While the dried Prometheus ® Bronze Clay is strong, you still need to take the necessary care into account while working with it. You can engrave designs on the surface, file, sand, drill holes with hand tools or rotary tools.
After completing your design, it is easy to sand uneven surfaces, using sandpaper and sponges. It is a lot easier to do this step now - before firing the clay!
You have 3 choices for firing PBC ®:
1. Conventional method (*)
Place the dried piece (or pieces) on a stainless steel grid and place it in the preheated kiln at 820 ° C (**). Wait until the kiln returns to the correct temperature and fire the piece for 30/45 minutes.
When the firing is complete, place the piece on a heat-resistant surface and wait until it has cooled, or cool the piece in cold water while it is still hot. (***) This will cause the black layer to come loose. To clean the piece you can put it in a hot solution of a Safe acid bath.
(*) This method is recommended especially for large pieces; figurines etc.,
(**) Most kilns are cooler near the door, place your piece close to the rear in the oven.
(***) Dont do this with a stone or glass in the piece.
2. Carbon Method
This is a 2-step method.
Step.1 Place the dried piece (or pieces) on a stainless steel grid and place it in the preheated kiln at 500 ° C, or on a stove. Burn the piece for 10 minutes, then place it on a fireproof surface and let the piece cool down.
Step 2 lay a 3 cm high layer of activated carbon on the bottom of a steel container. Place the pieces at least 1.5 cm apart and fill the reservoir with the activated carbon, close the container and place it in the preheated kiln at 820 ° C. Let the kiln heat up to the right temperature and fire for 60 minutes. When the firing is complete, allow it to cool in the kiln or carefully remove the container and let it cool on a heat-insulated surface until it is cold enough to remove your pieces.
Another firing table is 820 ° C for 2 hours, which is preferably used when PBC® (bronze) is combined with PCC® Copper. And at 770 ° C for 2 hours when combined with Prometheus ® White bronze clay
3. Torch Firing Method
Place the dried piece on a stainless steel grid. Lay the grid on a fiber brick or a thick construction brick. Fire the piece until it has an orange-red color for 5-10 minutes depending on the size of the piece. Avoid melting by moving the flame over the piece. When the burn is complete, place the piece on a heat-resistant surface and wait until it has cooled, or cool the piece in cold water while it is still hot. To clean the piece you can put it in a hot solution of safe acid bath. With this method a black oxide layer forms which partially comes off when you immediately immerse the hot piece in cold water.
My fired piece is still brittle on the inside and breaks !!
When the clay is fired it should be made entirely of bronze or copper, we call it sintered. If he breaks and he is still brittle inside, then he is not yet completely sintered. You can also hear it if you drop the fired clay on your workbench and it sounds a bit dull then it is still clay inside. You can simply repair a broken piece with pasta made from a leftover clay, let it dry well, sand it and fire it again.
Then you can do two things now. That is, raise the temperature or extend the firing time.
- If you raise the temperature, do this in small steps of 10 ° C.
- Firing too long is actually not possible so extend the time by an hour or more. (The first types of bronze clay had to be in the kiln for 6 to 8 hours).
The larger the piece, the longer it has to fire, certainly because the sintering process is more difficult with bronze and copper because of the oxide layer that is formed.
Prometheus ® Bronze Clay finish
Polish your piece with a metal brush and, if necessary, in a hot solution of a Safe acid bath then rinse the piece thoroughly with water and dry it. This gives a nice warm reddish color to the bronze.
Polish the piece with a polishing tool, polishing papers, a tumbler or polishing motor. You can add extra shine to your work with the help of polishing agents.