I tried making Egyptian paste / faience a while back and it didn't work out well. This was probably because I didn't have half the ingredients and I substituted them for other things that were probably very different. The result was a pinkish disc that had a dry texture.. not the blue / green glass that I was hoping for.
Now that I have all my things in Stoke, I've decided to have another try - but this time I'm going to be a bit more scientific in my approach.
I've got hold of four Nigel Wood recipes for Egyptian paste and I've made four test discs for each one.
I've kept them on cling film to dry because I don't want the underside to grow sodium crystals on it, as it will stick to the kiln shelf and also it means more water will evaporate from the topside which should result in more crystals.... That's the theory anyway.
I've left the test pieces in a plastic tub, isolated from any drafts, to dry slowly over the next few days. After we come back up from Surrey, I will fire them and post the results.
Only those that follow me on Instagram or Facebook will know that I quit my job, sold my house and moved to Stoke on Trent to study pottery full time at Clay College in Middleport. These last few months have been surreal and amazing.
I applied for Clay College after spending nearly a year trying to find a pottery apprenticeship. The 2 year course is brand new and it aims to give students the skills, knowledge, support and contacts they need to become self employed potters. It's taught by the UK's leading potters and so far, in addition to our awesome teacher Kevin Millward, we've had guest potters Clive Bowen, Nigel Lambert and Josie Walters.
I didn't actually think my application would be successful, but I thoroughly enjoyed the interview day which involved demonstrations and making as well as interviews. The day itself was so much fun and really confirmed that pottery is what I want to do, whether or not my application was successful.
Fortunately my application was successful and as soon as I found out I handed my notice in and put our house up for sale (which has recently completed). Luckily for me, my partner Adam's employers are super supportive and let him work remotely, so he's come up with the cats, Pepper and Jinx, to join me.
This term gone we focused on earthernware clay, mainly terracotta, as it's cheap and a good clay to learn with.
Our first project was to make two sets of six cups, three sets of three nesting bowls and two sets of three jugs. Our second project has been to make platters and dishes for serving food. I've really enjoyed the projects and found them challenging at times. I've made a few things I really don't like, but I've learnt some awesome techniques that I'm excited to explore in the future.
My highlight would have to be Clive Bowen's slip decoration demonstrations. Before he came, I didn't really understand his work but after seeing how he decorates, I began to appreciate the energy and life that he injects into his work by using his techniques and it's something I'm keen to emulate in my own way. I'm not much of a decorater, but this type of natural and free way of adding character to my work is something I like.
Clive with his three pronged slip trailer
My attempts at slip trailing
Lisa Hammond is another trustee and so far we've been visited by Kate Malone, Keith Brymer Jones, Mark Dally, Lee Kang Hyo as well as HRH The Prince of Wales..! (http://www.stokesentinel.co.uk/news/stoke-on-trent-news/royal-visit-prince-charles-gives-846865)
Ive wanted to get back to basics and build a wood burning kiln for a while now and with the street starting to warm up, I thought this weekend would be a good opportunity to make a start.
Using a combo of traditional bricks to create a base and the sides, I used white fireclay bricks on the inside to give it an extra layer of insulation.
I've chosen to make a 'downdraft' kiln, which means that instead of the heat going out of the top through a chimney, the fire comes in at the bottom circles round the inside and can only escape through a hole at the bottom that connects to the chimney. This is helps get the kiln even hotter.
Overall pretty pleased with the end result. It's a bit dodgy looking, but not bad for a first attempt. Will camp out next weekend and fire some pots in it...!
Reused an old kiln lid for the top
Creating the base
A mixture of dug field clay and hay. The hay makes the clay stronger and stickier.
After lighting it, we checked for smoke leaking and plugged the holes with more clay/hay
Fitted the wood burning chamber with a shelf to allow the embers to drop down and get air into the flame.
I used to really enjoy the cold weather.. but now I can't wait for it to start to warm up again.. one of the main reasons why is that my pottery workshop is FREEZING. Literally.
Cold clay is a misery to work but at sub 0'C tenperatures, the water in the clay starts to freeze and creates weird cracks in the block of clay that have to be kneaded out later.
To keep myself busy, I've been learning about the much warmer craft of forging. I had a few of the necessary bits already, so I only had to buy a blow torch to have a crack at making simple rings.
steel template ring in the sand mould.
The first step is to fill half of the mould with Delft clay, which is basically oil and clay mixed together. The ring that I wanted to copy is then half pressed into the sand.
both halves of the mould
The top part of the mould is then placed ontop and filled with sand which is then compacted down.
Pulling the two halves apart reveals the mould.
Channels are then cut into the mould to let the liquid metal in and let air escape.
As this was my first attempt, rather than melting down silver (melts at 950'C), I found some scrap aluminium that melts at a lower 600'C.
Here is the result:
ring with sprue still attached
The sprue is then cut off and the ring tidied up. I used a dremel to do it, but I do have a lathe from my grandfather's toolkit that I'm trying to figure out, as it would be perfect for tidying up rings.
I'm fairly pleased with the first rough attempt and will definitely be trying it with silver and maybe some interesting alloys like copper and silver (which is a Japanese metal called shibuichi), gold and silver (ancient alloy called electrum) or even a mythical / legendary metal called 'orichalcum'.
As well as my workshop being freezing cold (which I can warm with an electric heater) the clay also gets very cold and is much harder to warm up and is almost painful to throw with, meaning that I've been doing pottery less, which sucks!
However, before I started slowing my pottery down, I did manage to get a decent result from the local reduction copper glaze I posted about previously and here is a piece I was commissioned to make for a colleague:
I've also been practising mugs, consistency and handles, which can be seen here:
In the finished piece, you can see where I have layered the local reduction glaze thicker, it has created red / blue / purple streaks and run slightly. I think that this glaze is particularly influenced by the firing schedule and so it might be worth making some test tiles and seeing what effects I can produce by adjusting the firing.
I've been thinking for a while about making a glaze known as 'copper red'. This might just sound like words, but copper glazes only turn red in a reduction atmosphere - where there is no oxygen available, such as in a gas kiln where the flames burn it all off.
I only have an electric kiln and I'm scared of using gas, so I turned to a really interesting and not that widely exploited material known as silicon carbide, which is the grit on most sand paper.
By mixing just 0.8℅ of silicon carbide into a copper glaze, it can create a reduction atmosphere within the glaze itself. At high temperatures, the silicon carbide changes into silica (glass, which is obvs very handy to have in a glaze) and carbon. Carbon is very reactive and readily grabs and steals any oxygen available in the glaze and changes to carbon monoxide and dioxide.
This gas then bubbles out of the glaze taking the oxygen away from the copper oxide, transforming it into copper metal (it also does this to other metals too) which is pinkish / red.
The reason this glaze is tricky is because as the gas exits the glaze, it causes it to bubbled and if the glaze cools with those bubbles in, you'll be left with an ugly and unsafe bit of pottery. You can counteract this by slowing the heating of the kiln down towards its top temperature of 1200°C.
Here are my results:
... but those are green / blue, not red!
Yes, they are. I followed the recipe to the letter and got an idea of how the speed and temperature of the kiln should work from the recipe, but the glazes have come out copper green, indicating pieces were fired in an oxygen rich environment.
As annoying as this is, I'm actually really pleased with the glaze and I might even say this is one of my favourites so far..! For those who want to try, the glaze is called Panana Red fired in oxidization and you don't need to add the silicon carbide if you want the green colour.
It would be a case of back to the drawing board, but I got in contact with John Britt, author of Mid-Fire Glazes and asked him if he could offer insight (I was following his instructions after all) and here's his reply:
Totes chuffed that he took the time to reply to my question, he's like the boss of glazing and has tons of really useful YouTube videos.
So I'm going to follow John's advice and we'll see how the next batch goes!
NB - the glaze shouldn't be used in functional pieces as it can leach out into food. It can be used on the outside however. The bowls shown are just test pieces and will be chucked away. As someone on Facebook once said "You might know it's not food safe, but pottery lasts a long longer than you will, who knows where it will end up?".
After drying all the clay I collected, I then separated out orangey / yellow chunks, as these will be high in iron and affect the colour of the clay. I'll make a separate batch of iron rich Norfolk clay later.
I then added the dry clay into a bucket of water and let it slake down into a slurry, which I mixed with a blender to get smooth. I ran the mixture through a sieve but amazingly the clay was really pure and contained no stones or sand! This means it can be pulled out of the ground and thrown on a potters wheel as is.
The clay slurry was then poured into plaster moulds and left to dry to useable hardness. (Plaster helps to draw out moisture).
Once the clay had dried enough, I made several test bars, measuring 5 inches (my old school ruler didn't have cms).
I let the test bars dry completely before measuring them again - this is to get an idea of how much the clay shrinks when air dried.
I then fired two of the bars to 1050°C and the other bars to 1200°C. The tests below are on the lower fired bar.
After their firing, I measured ther lengths again and calculated how much they had shrink ((original length - final length) / original length) * 100 which was about 8%.
To calculate the amount of water the fired clay body absorbs, you first weigh the bars post firing and then submerge in water for 24 hours. The formulae is ((dry weight - wet weight)/dry weight)*100 and worked out as about 22%.
This is a simple test where you scratch the fired body with a nail to see whether it crumbles and if so, how much by. The nail didn't scratch the clay.
This is to see how the clay distorts when being fired and you simply place the test bar so it's not supported across the middle and after firing you check whether there is any bend in the bar. Happy to say there was no slumping.
The results of the tests indicate the clay is a typical earthenware surface clay with low (less then 15%) shrinkage and high absorption.
Fired to 1200°C
At the higher temperature the clay melted and stuck to the base I fired it on. Interestingpy the clay went from a cream colour into a mustard yellow, indicating the presence of iron, which makes sense, given all the orange bits I picked out.
The clay has almost no absorption now and resembles a stone or glass. This is because all the chemically bonded water has now been removed at the higher temperature and the crystalline structure of the clay now won't allow any water in.
The high fired clay has shrunk massively when compared side by side.
I've been in Norfolk this weekend visiting family and what better way to take advantage of the trip than to collect some clay!
We went to a local beach at Trimmingham which has exposed cliff faces that collapse onto the beach. After a short walk, consisting of me running up to mounds of earth and rubbing it between my fingers to check the plasticity, we found some clay.
A small stream came down from the top of the cliff and formed a slurry pit half way up.. which I enjoyed...
muddy feet or midget hands?
After searching for a bit, we found some nice looking grey clay without too much orange colour (iron) and filled a bucket.
While I was up the cliff, I noticed lots of orange looking slime which is called 'bog iron'. It comes from either iron in the soil being eroded chemically or by bacteria using the iron and excreting red iron oxide as a waste product. I knew instantly it was the latter, because the bacteria leaves a telltale oily film on the water's surface. In the past I've seen this and always assumed it was a rusting oil can or something causing the orangey slime oil, but no, it's totally natural.
Interestingly bog iron was one of the first sources of iron used in medieval times, which would be refined into pure iron metal. According to my limited research, refined bog iron actually has an advantage over modern processed iron ore because it contains more silica and this gives the resultant iron more rust resistance.. for a potter this is useful to know because it has implications should I ever use this orange iron oxide rich slime in a glaze, as silica is the glass base of the glaze.
While at the beach I also grabbed a load of seaweed..
Another mini history lesson warning! - when the Romans invaded Britain, they brought with them a great deal of technical knowledge, which included making glass. To melt sand into glass you need unfeasibly high temperatures... Unless you have a flux, which reduces the melting point.
The Romans had natrum, which is a salt rich mineral from a distant part of their empire containing dry salt lakes (Africa I think). After the Roman empire collapsed, so did the infrastructure providing natrum, taking the glass making capability and knowledge with it.
After the dark ages, experimentations with new ingredients lead to new discoveries and one of them was soda lime glass which used sodium as a flux to melt sand, much in the same way the Romans did a thousand years earlier with their natrum. One source of this flux was seaweed which as abundant as it is potent.
In pottery, the ash of burnt seaweed can be applied to a bisque fired clay pot and it alone can cause the outside to melt and turn into a glaze when fired.. which is what I hope to do once I've dried out the seaweed in my oven! (Fyi the smell is outrageous).