It has come to my attention, through email and the Hadar’s Clay Users’ Discussion Forum, that there is some confusion regarding the products on our store and the firing process. I would like to clarify these issues, especially for new users who may be less familiar with the history of the clays.
Let’s start with the products. True, there are many clays to choose from. I remember the first time I came into a ceramic store and was overwhelmed by the variety of clays, under glazes, glazes and stains. I didn’t even know what to ask. Luckily, the case with our store is a little simpler. Almost half the clays consist of an earlier version, which personally I don’t use anymore.
You may ask: Why aren’t they just discontinued? This is simply out of respect and consideration for customers who still want them. I can absolutely relate to people who want that product which works best for them. I don’t ask why, and it not my place to change their mind. If and when these clays are no longer in demand, they will be discontinued.
These are the “older” clays:
- Quick-fire Copper
- Quick-fire Bronze
- Quick-fire Brilliant Bronze
- Quick-fire Rose Bronze
- Quick-fire Bronze XT
- Smart Bronze
- Quick-fire Steel
The Traditional/Flex Clays are specialty clays intended for making flexible clay. They are not recommended for beginners.
All the clays mentioned above require a 2-phase firing schedule, with a cooling phase between phases. The first disadvantage is the long firing schedule. The second disadvantage is that there is a high rate of cracking with these clays. This is due the the cooling phase; the clays go through temperature changes before they are strong enough to withstand them.
The clays of the new formula were intended to overcome these disadvantages. The firing schedule involves one phase only and cracks rarely occur. These are the clays:
- Friendly Copper
- Friendly Bronze
- Friendly Brilliant Bronze (closer to gold color)
- Friendly Rose Bronze (more pink than copper)
- Champagne Bronze (pale yellow)
- Dark Champagne Bronze (slightly darker and deeper than Friendly Bronze)
- White Bronze (silver color but brittle)
- White Satin (silver color and strong)
- Low-shrinkage Steel XT
- Pearl Grey Steel (the only steel clay to be used on mokume gane)
The Firing Schedules
For each of the newly-formulated clays you can find an instruction manual in the right-hand pane of my blog. Each of them is fired at a different temperature but the firing process is basically the same. The most common problem in firing metal clay is crumbling after firing. This is mostly due to poor binder burnout. To overcome this problem, here is my suggested schedule:
- Ramp at 1800°F per hour to 1000°F (in a brick kiln) or 1100°F (in a muffle kiln)
- Hold between 1:00 – 2:00 hours. This is the temperature at which the binder burns up. The longer you hold at this temperature, the better. Bigger pieces or multiple pieces need longer hold time but I rarely hold for more than 2:00 hours. Holding 2 hours for small pieces doesn’t hurt.
- Ramp at 1800F to the goal temperature for the clay.
- Hold two hours.
This firing schedule takes 4-5 hours.
There are, of course, exceptions and complications. For example, when you want to fire more than one metal in one piece. Some of these issues are discussed in the Instruction Manual and some in my books. But for now, I hope this posting is helpful as a starting point. As usual, you can always reach me by email or use the Hadar’s Clay Users’ Discussion Forum and Hadar’s Clay Accredited Teachers for any questions you have.