Friday, 10 February 2012

Unsung heroes - I abandon the garden to visit our clay room

Shrammed! This is the word my mother uses to describe how you feel in this weather. Not unreasonably I have taken refuge in the greenhouse most of this week as the temperature has failed to exceed 0C. It is now looking unusually tidy: all the plants have been picked over, turned, pinched out where necessary, and watered if they really need it, the propagating bench has been cleaned out and the floor is well swept.

Pelargonium sidoides 'Sloe Gin Fizz' in the greenhouse at Whichford Pottery

Wait for it
Aeonium arboreum 'Zwartkop' flowering
in the greenhouse this week
There is some colour in the greenhouse; stray flowers and the steady arrival of packets of seed have kept me happy but I have delayed sowing until the weather is less extreme, so that I can ensure comfy growing conditions for the seedlings.

Everything outdoors is frozen solid, so I have resisted the urge to pick shrivelled heads off pansies as the more you fiddle with frozen plants the more damage they are likely to sustain. For the same reason I have postponed the willow pruning.

Lines of desire in the courtyard garden

Lines of Desire
A thin layer of snow can be useful for reviewing the layout of a garden as lines of desire created by various users are clearly visible. In this case (see left) Puss-Puss and the blackbirds obviously have different priorities. Musing on this was not enough to keep me occupied, however, so I went to pay a visit to Richard and Brian in the clay room.

These two are the unsung heroes of the pottery: it is their job to ensure that the makers are provided with an unbroken supply (about five tons a week) of high quality clay, it's a mucky job with no creature comforts and if the consistency of the clay isn't to all the throwers' liking they soon hear about it!

The bat cave
Brian. Extra hairy version.
The clay room is almost as cold as the garden at this time of year, and the constant dark and damp can make it like Gollum's cave (in fact bats occasionally roost there). It's a tough place to work, and noisy too, full of large, ancient machinery, everything covered with clay. No wonder Brian has developed extravagant winter plumage in an effort to keep warm.

Brian and Richard manage to stay remarkably cheerful, they are often to be heard bickering like an old married couple but they work well together. They are always happy to come and help move pots or solve a practical problem elsewhere in the pottery - I suspect they like the change of scenery.

Clay story
The clay that we use at Whichford has been developed carefully over the years. Three different british clays, each a different colour, are blended so that we are left with a clay that is tough, malleable and, after firing, frostproof. I can plant pots and leave them outside with no extra protection for winter after winter; even after years of use and abuse lamination in the frost is extremely rare, so we can with confidence offer a 10 year guarantee against frost damage.

The frozen clay piles

The clay is stored outdoors as natural weathering is an important part of the process. Brian then uses the growly Bobcat to scoop up the required proportions of the clay.

Brian in the Bobcat
This raw clay and lots of water is put in the blunger, a thing a bit like a giant food processor. Here the clay is mixed thoroughly into a creamy slip. It's at this point that the stones, fossils and so-on settle out and are left behind.
Raw clays mixing with water in the blunger
The slip is then pumped through a pipe across the ceiling of the clay room to a sieving machine, where the last impurities are removed. The liquid clay then pours into a large, lidded vat, known as the 'ark'.

Richard with the 'ark'
Once enough slip has been sieved the liquid is then pumped into the filter press, which takes a few hours to squeeze out excess water.  For flowerpot throwing a moisture content of about 25% is required, so a sample is taken from the vat and weighed so that the amount of water to be removed can be calculated. A float switch stops the press when enough water has poured out into a tank.

The filter press
The heavy slabs of clay (two tons per press) are released and dropped onto a trolley, then moved to the first pugmill. This contraption is a bit like a giant corkscrew inside a cannon. The clay is fed in, mixed with grog; the pugmill chops and mixes it. Grog is fired clay ground into a fine grit, it's an important ingredient which helps to keep the body of the finished clay open, enabling large pots to dry evenly, more quickly and with minimal shrinkage, and to resist thermal shock in the firing process. The grog content is another element which contributes towards the frostproof nature of our pots, as the correct porosity is vital.

Lively discussion as Richard and Brian load clay and grog into the pugmill
Chunks of this clay, dusted with grog to stop them from sticking together are stacked on pallets, wrapped in plastic and then left to rest for a few weeks. This is a bit like leaving your pastry to rest, the result is more plastic and less short, so that it can be thrown without tearing and splitting. These chunks of clay are then pugged again before being loaded onto small trolleys to go to the makers.

Richard's beloved dog Willow comfy on a pallet of maturing clay
You can see the second pugmill on the left
The throwers then take the big chunks of clay and cut them into pieces, weighing the pieces carefully as a set amount of clay is required for each style of pot.

Simon weighs out his clay balls for the next batch of pots
The clay is slapped about a bit to remove air bubbles but not too much 'knocking up' is needed as the second pugging takes most of the air out. Air bubbles would cause the pot to crack in the kiln. The clay is then centred and throwing begins...

Simon starts throwing

Come in!
Everyone enjoys seeing the making at the pottery, but if you visit us do please go and see Richard and Brian in the clay room as well, don't be intimidated by the loud rumblings and chuggings of the machinery! They enjoy having visitors and explaining the processes - and it is genuinely one of the most interesting and overlooked parts of the pottery.

1 comment:

  1. What a wonderful post, Harriet! Our visit to Whichford last Spring was a delight and everyone there was so friendly and willing to take time out of their busy day to show us everything we wanted to know about the making of your wonderful pots. We spent some time with Brian, as he patiently explained the workings of the clay room to us complete neophytes and with Simon upstairs as we marveled at his skills at the wheel. I always wished that I would have taken more notes while I was there because terms like pugging, knocking up, grog content, arks, and blungers should not go without note. Thankfully, your post fills in the missing details. And on our next visit, we look forward to saying hello to Willow!