Simplest Mould, Drop Out Mold

The Potter's Dictionary of Materials and Technique by Frank and Janet Hamer recently came into my possession. It's a British publication. It is astounding how many pottery terms have different meanings. There may be a language barrier. I did get the feeling that Mould is used rather than Mold. You must forgive me if I used the two interchangeably here.
There are many different types of molds for clay material as well is different materials for making them. I'll begin with the simplest, that is a clay mold.

Starting with a rather thick slab of porcelain, pushing in a borrowed antique button collection this Mould was generated. It's just that simple to make a mold. This slab is bisque fired to cone 04 or 1800°F/1000°C.

Using it is an uncomplicated operation of taking a small ball of Egyptian paste and smash it in to the depression. Egyptian paste comes out rather easily until the mold becomes water saturated. Once the mould is water logged you may either set it aside to dry or dust it was a little cornstarch or rice flour to aid as a release agent.

In the image to the right shows a small slab of clay in which a screw was impressed. After being dried it was fired to approximately 1000°C. A small coil of Egyptian Paste was pressed into this form/mold and released. A straw was used to place a hole in the top of coil forming these beads. Pretty simple, eh?

Twice-cooked travellers

Thanks Anitra, for the invitation to contribute. I have already learned a lot from you, and now Kriket as well - thanks to you both. My background is in glass and I am a newcomer to faience, so don't expect any expert advice here, probably more in the way of problems and questions...

Unfortunately I've had to be away from home a lot lately which has been frustrating... However, on the latest trip I decided to take it all with me. The first photo shows my tiny portable kiln and raw materials ready for the road.

I hadn't used this kiln before for temperatures higher than 540C (annealing glass beads) and I forgot to take with me the instructions for the controller. Searching online for those instructions led to an important discovery - that the top temp for this kiln is actually 920C not 1050C as I had thought... Would that be high enough for the paste? I had a go anyway and the results seemed OK, using Anitra's recipe of 16:4:2 (+ Cu Carbonate), firing the kiln at maximum for nearly an hour - but no pyrometer so not sure exactly what actual temperature. Just to see what would happen, on my return home I re-fired the pieces together with a new batch in my larger kiln, to 1000C. They don't appear any different after the 2nd firing... but at least don't seem to have suffered at all. Now I think I might try fusing two or more fired pieces - or adding detail with fresh paste to fired pieces to see if it's possible to build up more complex pieces in stages. Has anyone else tried doing this? I imagine the new bits will simply shrink and crack away from the old...

The second picture shows some of the twice-cooked pieces.

Now a very basic question for those who have more experience of this material. The mushroom-shaped lump, top left, has thicker glaze on the right-hand side and it has also bubbled - looks quite nice, actually, though doesn't show up very well in the pic. Before firing it had a lot more of the salty efflorescence on that side than the other, possibly due to the sun shining on it as it dried. Anitra has mentioned size and position in kiln as factors affecting glaze thickness, but would I be right in assuming that uneven drying could lead to uneven wicking of the salts in the mix and thus to uneven glazing? Has anyone found out how to avoid this, or perhaps how to exploit it in interesting ways?

Coming up... I'm wondering about making and using moulds (or is that "molds" with you?) for faience. Anyone out there with ideas or experience? I'm already messing around with the basic paste ingredients and an unusual glass-moulding technique, hoping to report back soon...

Some results

Above are the results of the firing (following on from my last post). I was predominantly making a batch of dark blue beads as I knew they would not be affected by 'the flash'. In this firing I did a couple of test wires to see if I could subdue 'the flash' on the lighter copper, turquoise colours.
Following Anitra's advice I painted some of the wires with kiln wash and I left some of the wires bare. I did, however, clean down all the wires first - grinding off any residue from past firings. I also used a variety of gauges of wire from .7mm to 2mm. After painting the wires I left them to dry thoroughly and actually left the beads to dry out a little as well before carefully threading them onto the coated wires. They went on smoothly enough with little disruption to the kiln wash on the painted wires. There seemed to be no indication of the 'the flash' during making or during drying - even on the wires that were uncoated.
BUT when I opened the kiln today there it was! It had appeared on the gaps of the wires between the beads - on both the wires painted with the kiln wash and the plain wires. I was hoping it would have been contained to these areas but on closer inspection I can see it still migrated to the surface of some of the beads.
So I am due to make a large batch of pale colours and of course am concerned as to how to beat this. Anitra, you suggested coating the wires in a wax of some sort? Do you mind explaining that process please? My mind is telling me that the wax will just melt....... Also I have read that another ceramist having this problem coated her wires with enamel but again I have no idea what that would entail.
Is there another kind of wire that could be used in place of a nickel based wire? Perhaps stainless steel - is it ok to fire this in an electric kiln? I wonder if  it is possible to source thin 'ceramic' wires of some description as it seems to me that it is the metal that is the key to encouraging the growth of 'the flash'.

function over beauty

4 section bead rack to hold wires of different lengths

and to maximise kiln space

standard 3 tiered rack - holds about 20 wires

                                    

beads drying a little before threading them onto 

their wires

Several people have contacted me in the last week or so asking about how I support my beads whilst they are drying and then during the firing process.  I have custom made bead racks out of earthenware clay to suit both the size of my kiln and the size of the beads I want to fire. Larger beads need more support so need to be on shorter nichrome wires supported at intervals of about 10cm or less. Tiny beads not weighing much can be threaded onto longer 20 - 25cm wires. The racks are not elegant like the ones you would purchase from a ceramic supplies but they are way cheaper and do the job just as well. The beads sit on their wires for about 3-4 days before being fired to around 1040 degrees C. Then with a bit of luck they come out of the kiln transformed from white, dry, unexciting beads to shiny, glossy, gorgeous ones, ready to be designed into jewellery

Matt and Gloss Surfaces

Matt surface is fully mature and smooth in Egyptian Paste without
any gloss. An increase in alumina makes the surface more refractory creating a matt surface, or so I've read. I suppose conversely, this means that a decrease in alumina would create a gloss surface. Someday I'll monkey around with aluminum hydrate just to prove this to myself. For now, I use different recipes to achieve the gloss or matt.

It may just be the glaze layer is thinner causing the matt surface. It cetainly is not because it is underfired; experiments were run taking the firing a cone or two higher with no discernible different in the matt. This roses has a relatively thick layer that is quite smooth yet still matt. However, it is notice that the shinier Egyptian Paste layer of glaze is much thicker then that of the matt's.

Because I fire on my "bead islands" there does seem to be a gradient from top to bottom of the amount of glaze formed on the bead surface. In the image above, you can see the turquoise bead is nearly white where the glaze formed thinner. Where the glaze formed thicker of the surface is smoother.

The image to the right has two different recipes. The one in the foreground, the turquoise figure and beads is the recipe used in all my post up til now shows a Matt surface. The choir/pale figures in the background is the gloss surface recipe containing more sodium salts. All of my carefully sculpted details are obliterated.

Efflorescence in this gloss recipe was so great it was difficult to load it in the kiln without disturbing the surface. Sticking was another problem; a thick application of kiln wash was always necessary. The cleanup was labor-intensive, especially bead wire. The Matt Paste doesn't stick nearer so much.

On top of this I found I personally prefer the Matt surface , because it looks like Egyptian Paste from antiquity. Plus that, more surface details/textures are discernible with the matt Egyptian Paste; that is important to a sculptor.

The gloss surface has a crackle network that could be a useful design element if considered. Even though I'd abandon the glossy recipe for some time now, I must re-examine gloss recipes. Gloss does seems to be the one that comes up more often in questions/comments.

A curious effect

Hi Anitra,

I have a noticed in my last 2 firings that quite a few of the beads have an unusual, yellow, fluorescent sheen to parts of their surfaces. It seems to be appearing on the paler colours - either the plain beads (with no colouring oxide in them) the pale turquoise beads and some of the beads with rutile as a colouring oxide.

It is quite unsightly and I am at a loss as to what is causing it and how to rectify it. I remember this happening on a random basis years ago.

I do not think it is being caused by the salt in the water as it has not occurred during all recent firings with salt present.

It only appears on some beads on each of the wires - others on the same wires are yellow free.

I feel it could have something to do with a reaction with the nichrome wire somehow and it is flashing onto the beads. It seems to be most obvious on the tops of the beads and at the holes.

I have bought brand new wire and threaded almost dry beads onto clean wires to test if it was happening during drying and it still occurred.

I have noticed it appear at times while making the beads - so it is present before firings. It seems to appear it of no-where.

If I look closely at the gaps in the wire between beads pre and post firing I think I can detect a small amount of greenish/yellowing on the wire.

Hmmm very curious and if anyone has any thoughts I love some help please.

Firing Egyptian paste cone 04, 1940°F/1060°C

Opening a kiln is a kin to payday. Open that envelope, there in find exactly what you've work for. Every now and then it's short or there's a bonus, either way you find yourself investigating why. It's kind of nice when firings go as planned.

Looking so generic going in, then turning brilliant coming out, it always surprises. It's the same as glaze firing, but you skipped one step (actually 2 steps, the bisque and the glaze application).

Firing hotter just to see what would change is a bit of a let down. The differences in color were only slight, possibly nonexistent.

Here is Proof that Thicker Paste forms Thicker Glaze

Make a ball of Egyptian paste then cut it into two equal halfs; take one of your halfs and divided it in half again. So now you have one half and two fourths made from your original ball of Egyptian paste. Taking one of your fourths and rolling it into a ball and joining the remaining fourth to the half yielding two balls of Egyptian paste, one being three times more volume than the other. Press these into a button form, dry and fire them to cone 04 (approximately 1000°C) and now you have what is pictured here.

The button on the left is one third the volume of that on the right. Both buttons started with the same surface details. However the larger one developed so much more glaze that it obscured /flooded the texture. Photographing on a dollar bill should give you perspective on both size, detail and color.

These two buttons were fired along side one another in the kiln; the reason that is mention is that placement in the kiln also effects the glaze. However, this is a subject for another post later on. The unfired Egyptian Paste or 'greenware', as potters call it, shows an even deep texture than the fired ware.

For now we have our first little fact for the behavior of Egyptian paste. Fact #1. The larger the volume of paste, the thicker the glaze. Well that is one fact down, 99 more to go!

Small Hole Beads

Looking at the faience from ancient Egypt, one has to wonder how they crafted such little beads. All of my attempts at piercing tiny beads, ended with a crack that was larger than the hole. How did the ancient Egyptians do it?

It can be done; we know that for certain by examining museum pieces, but how? What did the ancient Egyptians have to work with? Skill, a lot of time and bronze tools is the answer to that, but not much else.

That's what got me to thinking the answer had to the simple. Knowing that nothing organic survives at 1000°C (1800°F), a few pea size balls of Egyptian paste were threaded onto pine needles. These were dried leaning against the wall of a ceramic dish, in order to let it dry from all sides and place it into kiln without disturbing the glaze surface. It was fired pine needles and all. Much to my surprise, this experiment worked splendidly!

The Thicker, The Glossier

Stands to reason that larger/thicker pieces have a Glossier finish, than smaller ones. Does it not? A thicker piece takes longer to dry, yes? With longer drying time more salts wicks through to the surface, agree? The more salts on the surface the thicker the glaze forms, right?

The two figures in the image here are constructed from the exact same clay/Egyptian paste mix. They dried next to each other; they were fired along side one another in the kiln. Mason stain, pansy purple, was added to the basic mix, 2.5% by weight. You can observe here that the thicker the glaze the bluer it appears. On the bottoms where no evaporation occurs their color appears identical.

Lots of cracks developed in bigger pieces as they dried. Possibly, the introduction of sand or grog would alleviate this cracking. Of course additions to the basic recipe might also affect the color. The addition of grog would also improve this clay's ability to stand up. There’s always more experimentation to be done.

Well, That Did Not Work So Hot

When you're experimenting not everything works. In fact very few things are successful the first second or even a third try. But there is useful information in every try. Recognizing it might be tricky. More important you find ways to refine your experiments for the next trial.

Reasoning that ancient Egyptians probably did not have nichrome wire to fire faience on and yet they turned out exquisite articles made from Egyptian paste; they must have some technique of keeping the glaze from sticking. Probably something very common in their environment. Perhaps it was fired on a reed or stick. A burn match will hold its shape, it may even support the weight of something as little as a bead. It may sound silly now but it was given a try.

A number of organics were tried, bamboo reeds, little wood twigs, leaf stems, hey even spaghetti was employed. The spaghetti failed miserably; it cracked the beads half lengthwise as you may clearly see in this image here. The bamboo reed burnt away leaving just the tiniest whisper of ash; however when the bead fell away it hardly stuck to the substrate it all. We may have discovered something here.

It's worth trying again for other reasons too. Some nice uniform bead holes were formed using this "technique". Also noticeable is when spanding the kiln furniture the beads stayed in place if they were long enough. Definitely worth trying again!

Bluetooth Beads!

Continuing with the excitement from the last kiln firing here's an image of something that went right. Turned out well both front and back. This is a rather simple bead to make just time consuming. An IBM Selectric typewriter element is used to give a sort of modern hieroglyphics; you can see the individual characters impressed on the beads if you look for them. Too bad there is not a Greek character ball in the studio texture toybox.

With a few spacer beads the Faience beads are strung on monofilament/fishing line temporarily, just to get an idea how they would look. They sure would be lovely strung with copper beads. We will call them “Bluetooth Beads”!

The bottom/backsides of these beads have no glaze on them, because there was no evaporation from that side, and therefore no salts could accumulate on the surface forming the glaze. That is the efflorescence in action that was mentioned in an earlier post. They were fired sitting flush against the kiln shelf. An aluminum hydrate shelf primer kept sticking to a minimum; sticking really wasn't a problem with this Egyptian paste recipe. The unglazed portion feels like a fine grain sandpaper or etched glass. The glaze side is a rather matte glaze smooth to the touch.

Silica Sand in the Mix: remarkable results

Anitra

I'm not sure that I can post a picture with a comment on your blog... but here are some my first fired attempts (size of small disc shapes 0.5" or 10mm). The three grey ones at the top are unfired, the blue ones fired up to 1000 C (1830 F) and held there for about 30 mins. Do feel free to use the picture yourself and comment on it in any way you like.

There are several obvious things to my mind:
1. the paste is almost unworkable, so these are the most sophisticated shapes I could make
2. I probably handled the dry pieces more than necessary so may have adversely affected the surface
3. The grains of sand have not really welded together, so the fired piece is not much stronger than the unfired - maybe a higher temp or longer soak would have made a difference, maybe not...

I'm looking forward to experimenting with the finer stuff.

There is certainly clay in one area of the salt marsh... another avenue to explore as you say...

Alan


Say Alan, it is truly remarkable that you were able to do anything at all with your “sandy mix” of Egyptian Paste. They have a nice surface texture. How you were able to hold it together is testimony to your skill. You are bound to turn out wonders with the finer mesh silica in the mix.
As you can see I've posted your letter. I read that I can make you part of this "Blog Team"; therefore you will receive an invite to be an author shortly. You may post as often as you like just keeping it about Egyptian Paste of course.
-----------Anitra

Firing Egyptian Paste, Houston We have FAIENCE!!

Opening a fired Egyptian paste kiln is one of the more exciting occasions in the studio. You always know you will get some little gifts. If you're like I am you will have an experiment or two running. So there's going to be some disappointments too. I really shouldn't call them disappointments; we need to think of them as learning experiences. There's serendipity too!

This last Egyptian paste kiln firing was no exception to the excitement rule. The paste goes in the kiln so nondescript and comes out so vivid. There were some surprises. Just 2.5 percent pansy purple mason stain yielded a much deeper color than expected; I can cut that down to 1% in future firings. The base recipe for Egyptian paste without colorant came out a pale gray, nearly white. I imagine with the addition of tin oxide or zinc oxide a true white may be obtained. That is the basis for another future experiment. I had a few experiments going on in this kiln that will be covered later on. For now, I can say that over all I was pleased with this firing.

My bead island performed marvelously as expected. The beads came off quite easily. Of course there was a layer of shelf primer on the peaks to keep the bead holes from sticking. Painting them with a layer of wax resist will keep the salts/fluxes from being absorbed by the clay of the island. In this firing, I neglected to do this wax coating and yet there was little sticking.

This firing was cone 06, that's about 1800 Fahrenheit/1000°C. A cone firing is a measure of work done by heat rather than temperture; the cone is formulated to melt at a certain temperature so when it bends the kiln is said to have reach temperature. Were I firing by pryrometer I would probably have to hold the kiln at temperature. Most potters just fire up to cone 06 then shut the kiln off. In my case, the “kiln sitter” shuts the kiln off. My next firing I'm going to try taking the kiln up one cone hotter to see if I can get the paste to flux a little bit more. More variation in the color would be nice. The the beads look a little too controlled, not enough like the ancient Faience. Even so, some of the ancient Faience is this turquoise.

A Bead Making Technique For Egyptian Paste

May I present a one minute video showing how I fabricate a bead of Egyptian paste. As you recall, Egyptian paste is a self glazing clay, therefore you won't want to touch it while it is drying. This small video will show you the technique I use to let the bead dry and fire.

Egyptian Paste Bead Firing

Here is what I use to fire Egyptian paste beads in my electric kiln. This apparatus, a "bead island", is made of porcelain or any high fired clay for that matter; I like the B-mix clay body for this piece of kiln furniture, because it forms a thin point very easily. Once fired the bead island can be used many times. It's coated with two or three layers of kiln wash before each use. If it breaks I just make another..
Using the bead islands, allows me to form the bead from Egyptian paste, place it onto the tip of one of these peaks to dry and fire without ever having to touch it directly. Handling Egyptian paste after it dries would damage glaze that forms on the bead as it dries.

For smaller hole beads nichrome wire is used in my islands.

Back to Paste!

This little Guy on our left here was supposed to remind me to do some experimenting with Egyptian paste and report back to the world on my findings. Well for the past five years he's been as silent as an Egyptian tomb. Five years ago this blog was started with a lot of enthusiasm and then just sort of fizzled out. Surprisingly, I did have one comment in those five years; So, I know at least one somebody out in this vast universe is following my adventures in Egyptian paste. There's still a batch, maybe two on my reagent shelf of Egyptian paste that I mixed up years ago. Add a little water and elbow grease and I'm good to go. If I don't report back in a fortnight or so it's this little guy's fault and none of my own.

The Tried-and-true Recipe

There are dozens of Egyptian paste recipes and where to start is not always apparent. Add to this the fact that you can buy premixed; however manufactures can change formulation without informing you and it’s rather dear. This recipe from an old ceramics monthly (Behrens) was chosen for a number of reasons. First is mixed by measures, so there’s no need for gram scale. Secondly, there is no clay in this formula; it’s mostly quartz, which is close to the composition of the archaeological finds. Third, there are very few ingredients and it’s inexpensive. And lastly, it can be modified easily. For those unfamiliar with studio, hygiene I am mentioning this: it is IMPERATIVE TO WEAR RESPIRATOR when measuring and mixing anything that contains free silica. The recipe is as follows:

16 parts, silica (325 to 400 mesh)
4 parts, bentonite .
2 parts, baking soda
this is the basic mix to this add one half part copper carbonate for turquoise color. I’ve tried a few other recipes but this one is tried-and-true; it is adequate for the time being.

How can clay self-glaze? Efflorescence, that's how!

Every week I will introduce one little nuance on Egyptian paste. At this rate, we will acquire 52 characteristics of Egyptian paste in a year. Theoretically, anyone who can name 52 characteristics of Egyptian paste is somewhat of a master on the subject, no?
Moving on, efflorescence, is the term this week. I would describe it as a wicking of the salts in the Egyptian paste to the surface as it dries. The Egyptian paste has soluble salts in it; that is salts that are dissolved in water.
Here is an image of our miniature milking stool again; both before and after the firing to cone 06 (about 1000 C. degrees). It’s hard to see and photograph, but in the before picture there is a powder on the surface. The powder is like growing salt crystals. I’ll try to get a close-up photograph of the surface next time I fire a load of paste.

Working in Egyptian Paste

If Egyptian Paste is defined as self-glazing clay then this blog will consist of my adventures of trying to create with it. More than likely more pictures will be posted here rather than text, because pictures tend to be self-explanatory. It is hoped by sharing ideas, techniques and problems in working Egyptian paste with you that it will aid me in understanding this media.

I should sidebar here to say that Egyptian paste is not true clay but rather pulverized glass; it's about as pliable as wet sand. To the right is a little three-legged stool I formed (from a recipe I shall divulge further down the blog). I haven't learned how to put captions on pictures yet, but that won't stop me from enclosing them just now.
Furthermore, why the antiquities of this media are labeled Faience is beyond my comprehension. Faience is a majolica pottery made in the town Faenza, Italy. I visited that town years back and noticed that Egyptian paste looks nothing like Faience. I've read that the Egyptians themselves referred to it as "tjehnet"; a Google search on tjehnet will yield a few of the artifacts but the same search on faience will overwhelm one. In researching Egyptian paste numerous archaeological references were discovered, but little in actually working the "clay". Therefore this blog is to be the first comprehensive guide in working with Egyptian paste. Only you will be working alongside me as I discover this trail.