Clay & Slip

Clay

Clay Body is produced from a number of fine materials (Bulk Materials & Minerals). Most of these are mined, including Flint, Sand, Ball-Clays and China-Clay. The raw materials contain large unrefined objects not wanted in the body. These include oversize bits of sand and grit, lignite, and traces of iron compounds. So at all stages of clay body making, extensive tests must be carried out.

The clay we use at Royal Stafford tableware is provided to us by a specialist professional clay-body making company, and is delivered in liquid form.

Pressing Procedure

When the quality checks have been carried out on the clay slop deliveries and it has gone through sieves and magnets it is then pumped into one of our four presses, at a pressure of 200 lb. per. sq. inch. The presses are filled and emptied in rotation, which takes out all the excess water leaving clay cake. At this stage we control the clay hardness by determining how long we press the clay slop for and how much water we take out. When the clay is ready, it is dropped onto clay trucks and sent to the next process.

Pugging Procedure

The clay cake is broken into small pieces and put into a vacuum chamber, where all the air is taken out. (This stage is vital as it eliminates problems in all the following processes). After going into the chamber as clay cake it comes out the other end like a sausage. The clay is then cut to the required lengths, placed onto wooden pallets and wrapped in cling film to keep it at the correct consistency.

A ticket is attached stating the clay hardness and date pugged before going to the next process.

Casting Slip

Casting Slip is basically a fluid grey/brown paste a bit like mud. There are four things that go into making our casting slip: Clay (as described above), Soda, Silicate and Water. It is essential that the recipe, procedure and quality checks are carried out accurately as we must keep the slip density constant within very narrow limits. We cannot make rapid changes.

To make the slip, water (about 20 buckets full) is poured into a blunger (mixer), then the soda (15oz.) and the silicate (117oz.) which has been thoroughly dissolved in boiling water is added. The blunger is then run for 10 minutes to mix the chemicals in the water. Then, the clay is cut into small pieces and added to the mix. After the last piece of clay has been put into the blunger, the mix is blunged for two hours.

| Main | Clay & Slip | Moulds | Casting | Production | Firing | Glaze and Spraying |
| Decorating | Glost Kiln Firing | Packing & Despatch |