Getting into it
The Pottery Club was closed during the Covid19 lockdown and access by members to use club equipment resumed in level 2, so it has been a couple of weeks where we have had limited access. Last week I loaded the kiln for a bisque firing, it included the tankard that was raffled, and also my very first order of a small wave design bowl – very excited having had my first order using the online shop!
The Covid lockdown really highlighted how dependent I was on the Club’s equipment to finish off pieces of work. Don’t get me wrong, I had all I needed here at home to make the pieces, but just not the kiln, which perhaps created some subconcious thoughts that resulted in non action. I had planned to create a whole new range of items over the 4 week lockdown, but managed only a couple of things. This kiln load I made once we were in level 2 (May), decided not to dwell on it all and just cracked on.
My Process
Step One – Make the Stuff. I used a range of clays in these pieces – slip cast porcelain, some low fire porcelain and a white stoneware with grog. Grog is finely ground up bits of fired clay that is used to reduce shrinkage in clay. I have decided I dislike the clays with grog for making the bowls and cups, will have to make it my mission to find a form that loves the grogged clay.
Step Two – Bisque Firing. So once I have made my pieces and they have had a few days drying out they go for their first visit into the kiln. This firing is a bisque firing and reaches a temperature of around 950°c. Really important they are dry – bone dry, if they aren’t they could explode in the kiln. In a bisque firing it is heated to a point where there is no chemically bonded water in the piece, the piece is still porous which is important if we want to glaze it.
The bisque firing takes just over 7 hours, and the work is cool enough to open the kiln in another 24 hours. The opening of the kiln is an exciting yet terrifying moment “did I dry everything properly?” “did the shelf props stay upright or did they fall over and crush everything?”.
This time there was a sigh of relief, everything intact and no damage.
Step Three – Glazing. This part of the process seems to take me ages, I don’t know if it is because I get carried away with all the options for glaze combinations or that I am just mucking around too much, in any case, it takes ages. What I have learned in the last few months is that if this part is rushed the results aren’t as amazing as they could be. I am still learning my way with a lot of glazes and so there have been a few ‘meh’ moments.
The items go into the kiln for a glaze firing and we crank it up to 1180°c, it takes longer then a bisque firing – how much longer you ask me? well I don’t actually know cause there is a computer thingy that controls it all and my maths adding the temperature increases is crap…… a glaze firing takes longer than a bisque firing. In this stage we take the clay to maturity where it vitrifies – this means there has been a bonding of particles making it strong and consolidation or reduction in porosity which makes the item impermeabile to fluids – no one wants a leaky cup or bowl! The temperature also transforms the glaze into a layer of glass on the item. Just like opening the kiln after a bisque firing, there are moments of nervousness opening up after a glaze firing. It takes around 36 hours for the kiln to come down to a temperature that is safe to handle the items. Open too early and there is a risk that a temperature change can shock the items and cracks will happen.
This kiln load had a couple of wee accidents, but nothing major – see how the tankard is leaning over? The high temp wire that I made some stilts to prop up the tankard melted over, caused a wee blemish on the underside but nothing that can be seen. The tankard was won by a wonderful supporter in Upper Moutere and she chose a green celadon glaze to finish it off.
Here are some of the pieces from the last firing that I am really happy with. If you want something similar, head to the online shop to order, or if you are wanting something different feel free to email me at rebecca@boycemgmt.co.nz and let’s discuss what we can do for you!!
