Research
Information for makers
All of the blue pattern work is applied as slip at the leatherhard stage. After drying the pots are bisque fired to 1000 degrees centigrade, Orton cone 06. The glaze firing goes to 1120 degrees centigrade, Orton cone 01.
SLIP RECIPE
2 parts Valentines red earthenware clay
1 part ball clay
7 to 8 % cobalt oxide
2% red iron oxide
(Please note: I always test each batch of slip for colour intensity. If it is too strong then more clay is added. If it is too weak then more cobalt is added.)
GLAZE RECIPE orton cone 01
* Based on an ALAN CAIGER-SMITH recipe
Lead Bisilicate 56
Flint 8
Cornish Stone 10
Standard Borax Frit 8
Zinc Oxide 4
Tin Oxide 8
Lithium Carbonate 2
RUTILE GLAZE STAIN RECIPE
1 part Rutile Light
1 part orange and yellow commercial glaze stains mixed
The above is mixed with a little tin glaze to help it melt into the glaze surface and a lot of water. The stain must be applied VERY thinly on the glaze surface or it will bubble.
WARNING: All glaze materials vary. Glazes on tableware with lead (even lead frits) must be tested for lead release regularly. I test my work about once a year at:
CERAM RESEARCH, Queens Road, Penkhull, Stoke-on-Trent,
ST4 7LQ , England tel: +44 (0) 1782 845431
STENCILS
In addition to scissors I now use a “plotter-cutter”.
I have a ROLAND ‘Sign Maker’ Camm - 1 Pro, made by ROLAND Digital Group.
The UK distributor for Roland products is Patrick Thorn & Co. tel: +44 (0) 1784 466474 - but there is likely to be a web site for Roland which would give your local distributor.
I have an Power Macintosh G3, with Adobe Photoshop and Illustrator software, plus “Streamline” software to select outlines for cutting and “Cutline” software which is the interface between the computer and the “plotter-cutter”.
Look in your ‘Yellow Pages’ under Sign Makers’ Supplies for where to buy materials that are specially made to be cut on a “plotter-cutter”. You can buy rolls of ‘vinyl’ ( - sticky backed plastic) or sand blast rubber in various thicknesses. You can also ask for “ application tape” which is like a 2 foot wide roll of masking tape that has less tack than normal masking tape. (see my website www.morgenhall.co.uk and look under ‘background’ then ‘research’ for more information on cutting stencils on a “plotter-cutter”
Morgen’s new and as yet unpatented “Direct Transfer Print” method
I use “Twin Cal Uni” or “Tru Cal” transfer paper from Tullis Russell, Brittains, Stoke-on-Trent, ST1 3QS England. tel: +44 (0) 1782 202567
1. Mix clear water based acrylic printing medium with powdered ceramic colour. (I have a good blue from an enamel blue which must be cobalt based as it fires to Orton cone 01 without losing colour.)
2. Apply the colour to the transfer paper and allow to dry.
Multiple layers of colour can be built up to a maximum of about 1 mm thick. Patterns can be made, for example shapes painted onto the transfer paper in one colour, leaving some background area on the paper empty, and you can sgraffito though this colour first then allow to dry, then more shapes or texture of another coloured layered on top of the first colour and filling the background space on the transfer paper, and so on.
The colour can be applied in any way you like - with different textures as a result - from screen printing to using a paint roller or hand sponging and brushing.
3. Cut a stencil from the now dry, coloured transfer paper. (note that the colour on the transfer paper is NOT covercoated.)
4. Place the stencil colour side down onto the freshly rolled out slab of clay.( - or in my case, to the freshly ram pressed form.)
5. Roll the stencil into the clay surface with a rolling pin. ( - or ram press the surface)
6. Wet the backing paper and allow the water to soak into the backing paper for about 5 minutes.
7. Peel off the backing paper - hopefully leaving the colour stuck to the clay surface!
- a method of direct printing colour onto clay that can achieve crisp fine embossed edges and detail.
ROULETTES and STAMPS
I bought my brass ‘roulette’ wheels from:
Fine Cut Precision Ltd, Marlborough Road, Lancing Business Park, Lancing, Sussex, BN15 8UF , England tel:+44 (0) 903 750888
Please Note: Fine Cut Precision Ltd. make book binding tools. In the book binding trade they do not call them ‘roulettes’. The size I use is called a “Decorative Farthing Wheel”. If you want to make HUGE pots then ask for a “Brass Roll” which has a wheel of about 5 inch diameter!!!
TOBACCO “MOCHA”
1. Buy tobacco for rolling cigarettes by hand. Put the tobacco in a cup and pour on only enough boiling water to cover the tobacco. Do not use too much water. Place the cup in a bowl of boiled hot water to keep the mix warm for longer and cover all with a lid.
2. Leave this for at least 24 hours.
3. Sieve the mixture and keep the liquid.
4. Mix in oxide. I used about 1 teaspoon of red iron oxide in 1/2 cup of tobacco liquid. Other colours such as cobalt oxide can be used, but finer particle colourings such as cobalt carbonate can cause the glaze to crawl.
5. Dip a wet clay slab tile or other form into slip. (if you use leatherhard clay you must be VERY fast because if the slip dries then the Mocha can not ‘branch’ through it.)
6. While the slip surface is still very wet drop tiny individual drops of the tobacco and colour mix onto the wet slip. A branching pattern will grow.
NOTE: Old recipes for tobacco Mocha seem to call for Horses or other animal URINE - which you can try if you must, but I have found the plain water + tobacco + colour to work sufficiently well.
