There is some confusion about the different varieties of Hadar’s Clay. I am often asked what does XT mean, what is the difference between Traditional and Quick-fire, etc.
For your convenience, I’ve uploaded to the right panel of this blog a file called “Map of Hadar’s Clays“, hoping it will clear up some of the confusion.
In general, Hadar’s Clay products are divided to 2 main groups: Quick-fires and Flex (also called Traditional; the term Traditional is being gradually taken off the label and will no longer be used).
The Flex group are clays with a very specialized application: making flexible clay. These clays, when mixed with glycerin, stay flexible after they are dried, with the consistency of leather. They clay can be cut, woven, folded, and knotted. Projects for flexible clays can be found in my book: The Handbook of Metal Clay: Textures and Forms (second edition). These clays also work very well with the Silhouette machine. The machine cuts shapes out of them without breaking sheet that it fed into it.
All Flex clays require pre-firing, or firing in two phases.
The Quick-fire group includes the rest of the clays. Some of them require pre-firing and some don’t. With addition of glycerine they will be somewhat flexible after drying but not nearly as much as the Flex clays.
Both groups are further classified according to their firing schedules. The Flex group includes clays which fire at mid- and high-fire schedule; the Quick-fires also include a clay with low-fire schedule – White Bronze – and a new clay which fires between low-and mid-fire schedule – Smart Bronze.
The symbol XT simply means that the clay is a later formula. For example, Quick-fire Bronze XT was developed after Quick-fire Bronze; it is a high-fire bronze which can be fired in combination with steel.
Quick-fire clays that do not require pre-firing (one-phase firing) are White Bronze, Smart Bronze, and Low-Shrinkage Steel XT.
The second page of the map classifies combinations of clays according to their firing schedules. It shows which clays can be fired in combination with others, and at what firing schedule.