It is a great irony that glazing - and multi-fired glazing at that - is absolutly crucial to my finished work. In general there's an alchemy and mystique that surrounds the creation of ceramics - a combination of magic and chemistry...and that's where the irony comes in. I studied Chemistry in 3rd and 4th year at secondary school but it was agreed 'by mutual consent' that it wasn't my strong point - so I spent about 4 months in the art department 'filling in' my timetable before my exams.
Fast forward to my time in the Ceramics Department at The Glasgow School of Art - and I began to see the benefits and practical application of Chemistry...oh my poor, long suffering Chemistry teacher would not believe it! I freely admit that it is not my favourite aspect of my craft but when the kiln is opened and you have created a multi textured, multi layered piece - well, that is magic indeed.
- I buy in glaze ingredients but mix up my own recipes.
- I always mix my glazes wearing a mask and gloves - and apply them in my outside workshop as some aspects of the process are hazardous.
- My base glaze is a Dolomite glaze with the addition of Lead Bisilicate to slightly lower its firing temperature whist still achieving the satin matt finish its prized for.
- Strange then that I add silicon carbide to create the surfaces that have become my 'trademark'. During the firing gases are produced at the top end of a stoneware firing and this is what creates glaze bubbles resulting in crater glazes.
- My colour palette is generally subdued...no brights for me. I use colouring oxides to achieve the mix of greens, russets, yellow ochre, greys and grey blues that suit my inspiration - weathered and worn; the silicon carbide also causes local reduction, which causes variegation of the colour and texture . I've recently returned to loading some of the glazes with copper oxide which creates a black with overlays of copper green.
- I prepare large quantities of my powdered base glaze, then use it as and when I'm glazing a piece, adding colouring oxides and silicon carbide, to the smaller batch.
- I don't sieve my glazes after mixing with water - which I try to take from containers that collect rainwater. This means there's an uneven mix and you can achieve wonderful random colouring and textural effects - or sometimes not!!
- First, I like to heat the bisque fired piece up to approx 70 degrees celsius In the kiln then take it out and glaze the interior.
- Generally, I pour a dolomite glaze without the addition of silicon carbide into the vessel interior - I 'swill' it around then pour the remainder back into the glaze bucket.
- Next step is to pop it back into the kiln, which is still heated, to warm the exterior of the piece.
- Out again, I place it on a whirler (metal and looks like a cake stand - but does as the name suggests!). I apply the 'silk' dolomite glaze to some sections then overlay the whole piece with the dolomite crater glaze. I use a bog standard household paint brush of varying widths to apply it - I also practice some 'application in action' by spattering and flicking the glazes. Sometimes I'll sponge back some of the glaze to enhance the texture of the final piece.
- Then it's into the electric kiln for it's first glaze firing - 1200 degrees celsius...I programme the kiln to do this carefully, with gradual increases in how many degrees per minute the temperature rises - there are key critical stages where you can loose a piece if it's done too quickly.
- This 'glazing and firing' process is repeated again at least once - but sometimes three or four times to get the desired effect. It can be a bit of a gamble - one firing too much and....... it's those kiln gods again!