PeterH

Is the handle also cast, or are you joining dissimilar bodies? PS Should you contemplate changing your process you may find some relevant comments in this thread, which covers more than the title suggests.

My guess at the physics of the process... Sodium Silicate is not a release agent, it's a deflocculant. It lets you make a workable slip with less water. But it's not the more the better, there is a sweet spot (which your usual casting slip will/should-be close to). Basically the mold sucks water out of the slip causing it to cast. The casting get slower as - - the cast walls get thicker (more resistance to water flow) - the mold gets saturated with water (and stops sucking) The first required patience (and perhaps optimization of slip properties). The second requires -- - either a thick mold which can comfortably absorb all the water that needs to come out of the slip to complete the casting. - or exceptional patience to wait while water evaporates out of the saturated mold, which then can start sucking again. - in either case starting with a really dry mold can only help. That's because in that case the extra water may saturate the mold even when you are only casting thin walls.

MOP over a black glaze

But probably only if you have high-current sockets installed. First can you confirm what your actual supply voltage is. I suspect that you are like the UK in having a notional 230V supply but actually receive 240V. [Most of Europe has the same notional 230V supply, but actually receives 220V. This gives inter-operability for most electrical appliances, but doesn't work too well for heating devices & light bulbs. The full story is in https://www.se.com/uk/en/faqs/FA144717/#:~:text=The UK used 240VAC 50Hz,including UK and Irish Republic.] Assuming your supply is -- and will continue to be -- 240V the socket will need to safely supply the current drawn by the kiln. Obviously this is at least the 20A on the kiln's plate. In the USA it would legally need to be at least 25A (see PS), other locations may differ. [If the actual supply isn't 240V you may need to worry about element resistances.] So which of these socket types do you already have installed? https://en.wikipedia.org/wiki/AS/NZS_3112 PS PSS I cannot read all the details on the kiln plate, could you post a larger image? Does the kiln have a plug? If so which socket type does it fit? Again a photo might help.

A and B series instruction and service manual https://ltt.arizona.edu/sites/ltt.lab.arizona.edu/files/SM and MED Paragon A and B series Instruction and Service Manual.pdf A diagram showing which elements should receive how-much power for various settings of the rotary switches is shown on right -hand side of p24 (26th page in pdf) and the top left of p25 (27th page in pdf). For example ... Firing Schedule Poster https://paragonweb.com/wp-content/uploads/A-82B-FSP.pdf ... I've no idea what the "Extension Switch" is.

Hopefully somebody knows how to achieve the "shimmer" you want without spraying. Can I suggest that you don't take the airbrush idea any further until you have carefully assessed the H&S aspects. I have no practical experience with lustres, but did know years ago I did know somebody who had a garage industry making them. He was so un-enamoured with the solvents used in main-steam commercial lustres that he restricted himself to using turpentine. Expensive but safer to use. A couple of references to start the ball rolling. How to Use Ceramic Luster Glaze https://ceramicartsnetwork.org/daily/article/How-to-Use-Ceramic-Luster-Glaze Use a properly fitted respirator that blocks fumes during application (1), and work in a ventilated space with plenty of airflow. Ceramic luster glaze has toxic fumes when it’s in liquid form. As long as the weather is nice, I apply my luster outside. Lusters https://demaine.org/wp-content/uploads/2022/04/lustre-ceramics-monthly.pdf Health and Safety and Overglaze (in particular lustres) https://demaine.org/wp-content/uploads/2022/04/health-safety-and-overglaze.pdf Health and safety in ceramics is always an emotive issue and I am well aware that it is up to the individual to become acquainted with the potential hazards and the risks associated with the materials and work methods employed. Ultimately we all have to take responsibility for our own actions. The options available can be discussed under the following headings • Substitute materials/work practices • Dilution ventilation • Local ventilation • Personal ventilation Unfortunately lustres contain solvents and there is no safe way around this apart from switching to reduced lustres. Dilution ventilation means having windows open and a fan drawing the fumes away from the workplace. This is satisfactory if only small amounts of lustre are being used. Local ventilation means a booth constructed over the workplace drawing the fumes away. Personal ventilation is the use of a respirator while working. My method of protection from fumes is as follows. I use a fume booth constructed by my husband together with a respirator while I have developed a method of working that limits my exposure to the hazards involved. I use a resist method whereby I estimate that 90% of my time is spent using lustre resist which is quite inert. The other 10% is the actual application of the lustre, as all the fine lines apart from some gold pen work is achieved by resist. I am confident that I am limiting my exposure to lustre.

Just to remind you that volumetric blending is sometimes helpful. If you wanted to make test tiles with 1.5%, 2.0%, 2.5% & 3.0% SiC you could mix up 4 glazes, or you could mix up a 3.0% glaze and "dilute" it with commercial glaze. You can then make a smallish quantity of an x% glaze by mixing 1 volume of the 3.0% glaze with (3.0/x)-1 volumes of the commercial glaze. (I would use a small syringe). Obviously this is an approximation, which assumes that the volume of SiC is negligible. 1.5% = 1:1, 2.0% = 1:0.5, 2.5% = 1:0.25, 3.0% = 1:0

+1 Would it be easier to use Brongniart's formula? http://www.potteryatoldtoolijooaschool.com/brongniarts_formula_made_easy.pdf A popular way to measure specific-gravity/relative-density uses a plastic syringe. https://ratcitystudios.com/blog/2017/11/14/specific-gravity PS If you cannot measure grams on your scales you will want to calculate the weight of water to fill the syringe. https://www.rapidtables.com/convert/weight/gram-to-ounce.html

You might also be interested in this Service Training Manual. Skutt:Troubleshooting Theory https://skutt.com/images/Error-Codes.pdf

Re lava glazes - the mesh size of the silicon carbide can influence the effect it has, Testing Silicon Carbide Grits in Cone 6 Lava / Crater Glazes https://www.thestudiomanager.com/posts/tag/lava+glaze The horizontally-fired test tiles at an angle to show some of the texture. There is virtually no lava / crater effect with coarser grits. The finer grades of SiC are often sold for grinding/stone-tumbling, rather than pottery. PS SiC is also used for local reduction, where the trend also seems to be towards finer grades. https://glazy.org/materials/15401 Note: the description mentions fine grades of silicon carbide from 450-600 mesh. Lately a number of recipes call for even finer meshes, from 1000-1200, for producing evenly locally reduced glazes like celadons. A wide range of mesh sizes can be found online from lapidary supply stores.

Watercolor Cloisonne Process https://karensioson.com/watercolor-cloisonne-process/ Seems as good a name for it as any other. Some sort of texture medium, and some sort of paint. ... and a suitable subject and significant skill/dexterity.

An oldie from when people were moving from cone 10 to cone 6. Boron in glazes https://www.ceramicmaterialsworkshop.com/uploads/5/9/1/2/59124729/katz_tf_boroninglazes_0912.pdf

If unfired clay was it was mounted on paper you couldn't then fire either the clay or a glaze without damaging the paper, so probably not ceramic. Maybe gesso was used to create the the texture and then painted? https://en.wikipedia.org/wiki/Gess ... nowadays there are a variety of other "textural mediums", often combined with the use of acrylic paints. Historically gesso was often used used to create texture on picture frames. PS Like Babs I'm a little surprised if it is on paper, but ... https://mitchalbala.com/how-to-gesso-paper/ When you apply gesso to paper, it will wrinkle and warp as the paper’s fibers expand. If you use a heavy enough paper, it will flatten out nicely as it dries. But if the paper is too light, it will never dry completely flat. For this reason I recommend at least 140 lb. paper.

In case it's of any interest, this pdf includes a reprint of the original Stull chart paper. https://tinyurl.com/nhz64wy3 ... and a reprint of "Cobalt colours other than blue".

That confuses me too. IIRC you measured 243V in and 16.5v from one arm of the output. As the transformer is nominally 230v to (12+12)v surely you should have been reading (240/230)*12v= 12.5v. It's either a massive reading error, or the transformer isn't working as advertised. Barring shorts inside the transformer, or substantial "stray" currents through one of its coils this seems wierd. If the joints are easily breakable/re-makable it would be interesting to measure the transformer outputs open-circuit (and recheck it's inputs). ... and confirm the voltage across the relays input is now zero.

An old clayart post giving a selection of tips for throwing and joining large-ish pots in sections. throwing tall pots http://www.potters.org/subject09085.htm Including the use of plastic-wrap: to eliminate a great deal of the time required for the lower portions of sectional pots to set-up before attaching and working the upper section(s). ... no idea if this would have any relevance to coiling thick/heavy pots as well.

... or maybe you were remembering this. Which I suspect wouldn't generalise scale to a 30 gallon qvevra. https://tinyurl.com/36ap7kh8

https://youtu.be/2xOGWsFJ4DA I'm interested if you remember any more details . The closest thing I've found yet is this: Video at https://youtu.be/2xOGWsFJ4DA I wonder if you can do the same thing with coil-building (which may be necessary/helpful for larger pots).

This thread may be relevant: Have you fired any test tiles? If the above is relevant I would have expected them to come out something like the outside of your mug.

How do you support the pieces when firing; flat on the shelf, on a waster, on sand, ...?

Good spot. Several nice examples in https://wander-lush.org/clay-qvevri-wine-shrosha/ including ... and support in the kiln with bricks & small stones

Wow, it only takes 10 mins. Throwing/ Making a Onggi Pottery(Part 1 of Part 2)Korean Potter

Stumbled across this while researching my last post. In case anybody is interested ... Throwing Punic Amphorae: An Archaeological and Experimental Approach to the use of the Potter's Wheel in southern Iberia during the Iron Age https://exarc.net/issue-2021-2/ea/throwing-punic-amphorae-archaeological-and-experimental-approach A slightly odd format as the text is in a pdf file, and the diagrams have to be downloaded separately.

From https://tinyurl.com/jtcjby88 We also purchased this $34 amperage detector from Bartlett which is a tiny circuit board you connect to the kiln controller and has two white leads connecting to a ferrite ring. You thread one 220 volt power lines from each relay to the heating elements through the ferrite ring, which measures the power being consumed. This allows the controller to compare your current power draw to the original power draw when you installed the elements or in our case when we installed the controller. The controller tests the elements for about 60 seconds prior to each firing. A decline in amperage used is charted to determine your element aging and any sudden decline indicates the failure of an element. I think it also does other helpful things, like reporting the power consumed (and its cost). Don't know if it can detect things like stuck relays in real time.

Are you going to fit a current sensor?