When it became clear that the idea of making pots with a vertical extruder was going to be a success, Anthony’s next problem was: how to prepare enough clay to feed the insatiable machine. The original ribbon mixer, destroyed in the 1984 fire, would not in any case have had sufficient capacity. A filter press, and then a pan mill (imported from the UK in 1983 and 1986 respectively) were used for a while, but were unable to cope with the sticky nature of Matakana clay. Heritage Tiles Ltd in Warkworth seemed to be having success with a hammer mill and closed circuit sieving system using dry clay - a turnkey plant pre-fabricated in Australia. Plans were laid to purchase that company solely to acquire their clay preparation facility. When it was obvious that the purchase was not going to be possible, MS Engineering Ltd was engaged to build a copy of the Heritage plant (but bigger, of course). Anthony had already built a large shed suitable for housing the plant, down a small slope between the existing factory and the creek. This was originally intended for the tile making side of the business, and its construction was accompanied by own drama. Just under the surface of the proposed site, the ground was discovered to be quicksand. The building ended up with a most unusual shape, due to a misguided attempt to save money by minimizing the roof area. The walls were made to slope inwards, creating a truncated pyramid. The basis of the new clay preparation set- up was a hammer mill, sourced in New Zealand and manufactured by Colletts of Dannevirke. Also included were disc feeders for adding grog, purchased second hand from AB Brick in Auckland, and a trommel sieve built by MS Engineering. One problem remained. The Heritage method required a pug mill to mix water into the dry clay and compact the resulting plastic clay body into blocks. The16” horizontal extruder that Anthony had purchased in Australia had no mixing facility. Fortunately, Winstones tile factory in Wellington had a machine for sale which comprised a 12” horizontal de- airing extruder with a shaft mixer mounted on top of it. When it arrived, our technical consultant at the time, Ian Crum, recognized it as one that he had designed many years before. After some major modifications by MS Engineering it was found to work well with Matakana clay.
So the set –up was now complete, and production started with two full time employees required to operate it. So it was extremely labour intensive, and there were other aspects of the process which were less than satisfactory. The clay was produced in the form of plastic blocks on a pallet. These had to be taken to the factory by forklift, several times a day, in all weathers, and up a steep and slippery metalled driveway. The final straw was the fact that the clay dust would build up in the machinery forming a cake which was so hard it needed a jack hammer to remove it. Anthony asked the opinion of a retired quarryman, whose advice was to abandon the hammer mill and comminute the clay by rotary hoeing in the paddock. This suggestion was adopted. Initially the dry clay was put through a vibrating sieve in the open air, but eventually the sieve was moved into the clay shed and a set of crushing rolls were added. It was realized that it was much easier to store clay as a dry powder in the clay shed and reconstitute it with water at the factory as needed. A box feeder from the trommel sieve was fitted with wheels and transformed into a trailer to be towed behind a tractor and used to bring the dry powdered clay to the factory, where the shaft mixer/ extruder was installed. Moving the final stages of the process to the main factory also made sense because by now (1991) the company was in receivership and running with a skeleton staff. The clay shed provided a home for a machine that ground reject terracotta into grog, to be incorporated into the clay body. The final piece of clay processing machinery to be added was a set of smooth rolls. The new method did not at first produce fine enough clay powder, and unsightly lumps were still visible in the finished pots. Anthony had brought a set of smooth rolls from England and they had been sitting unused in the yard for fourteen years. Following Ian Crum’s advice, the shaft mixer and extruder were separated and the rolls installed between them. It would have been much easier to leave the shaft mixer in place and install the rolls above it, but unfortunately the roof was too low.
So, Morris and James finally had a workable system of clay body production, after the elapse of ten years, thousands of hours of wasted time, and the running up of huge debts, which contributed to the company being placed in receivership. It is ironic that a business intended to exploit an inexpensive raw material, ended up spending a small fortune in processing it. A few years later, when the company was being run by a management guru with little knowledge of clay ware manufacture, it was seriously proposed to return the clay processing back down the hill to the clay shed. Many more man hours were wasted discussing this proposal before sanity prevailed.
By Mike Rose