PeterH

No, Min suggested switching to a commercial glaze used in an Amaco underglaze colour chart.

Any relevance? https://digitalfire.com/material/gerstley+borate ... at the bottom of the page, discussing substituting Gillespie Borate for Gerstley Borate ... Clearly, the Floating Blue itself is firing greener than usual. And the Gillespie Borate version is much bluer. You may be used to something in between these two. The green tones could likely be restored by a reduction in the cobalt and increase in the iron oxide.

I was interested to find this Australian article https://sydneynorthshoreelectrician.com.au/electrical-service-panel-how-to-calculate-electrical-load-capacity/ ... which contains these sentences It is commonly recommended that the load never exceeds 80 per cent of the capacity of an electrical service panel. and The National Electric Code recommends that the overall capacity of the load does not exceed 80 per cent, ... Which suggest to me that there is no regulation demanding "over-rating" of breakers (at least in that region of Australia). But there are both informal and formal recommendations that this be done - apparently for both continuous and non-continuous loads.

It would be nice if you started a thread on the topic in say 3-12 months indicating your successes and failures in this area. PS A less well-known technique to achieve reduction. Which I think I've only seen mentioned in a 1932 paper on copper reds.

Re-reading Digitalfire the second paragraph seems relevant.. Glaze Shivering https://www.digitalfire.com/trouble/glaze+shivering Shivering is the opposite of glaze crazing, the fired glaze is under compression and wants to flake off the body, especially at edges. However the route cause is a mismatch in the thermal expansions of body and glaze, thus the process of resolving it is similar as for crazing. It it much less common because glazes tend to have a higher thermal expansion than bodies and because they can tolerate being under compression much better than being under tension. Of course, if a glaze is under compression on the inside of a vessel, the body will be under tension and this can cause failure of the piece. When the body-glaze interface is not well developed an overly compressed glaze will be able to release itself much more easily, especially on the edges of contours. This can be the case, not only with low fired ware, but where engobes or slips are being used under the glaze. If the engobe does not contain enough flux to firmly adhere it to the body and develop hardness, it will not be able to bond to the glaze well. PS Time for some rim-shaped test-tiles?

If you are leaning that way have you explored slow-cooling in an electric kiln? Which can have a dramatic effect on some glazes. PS Some eye candy. https://ceramicartsnetwork.org/daily/article/Super-Cool-Slow-Cooling-in-an-Electric-Kiln https://cone6pots.ning.com/forum/topics/slow-cooling https://ceramicartsnetwork.org/daily/article/Tips-for-Increasing-or-Decreasing-Crystallization-in-Glazes ... same glaze fired in a gas kiln: with the "natural" slow cooling of a gas kiln & with a "crash" cooling similar to that usually given by an electric kiln. https://digitalfire.com/schedule/c6dhsc https://digitalfire.com/picture/bestenazoh https://digitalfire.com/picture/3348 A discussion on iron reds in this thread http://ralpotterystudio.blogspot.com/2010/08/new-glaze-tests-710.html ... a fairly mixed bag, including Previous firings of this glaze at cone 6 or less without slow cooling produced dark browns. This is one that really requires slow cooling to get the red appearance, but proves you can get red reds at cone 6.

Idle thoughts while are are waiting for details of the kiln. If it's a 120V 17A Paragon they seem thin on the ground, see P5 of ... https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/IM5-A-and-B-Paragon-Inst-Man-Jan2017.pdf Possibly relevant. https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/A-11-9B.pdf https://www.theceramicshop.com/product/9663/paragon-a-11-9b-element-120v/ What mains supply do you have, and is 240V available? (Series wired with a 240v infinite switch would halve the current.)

I calculate 240/17.3 + 240/(8.6+8.6) + 240/17.3 = 41.7 amps I'm not familiar with kilns, but the difference between 40 & 41.7 could well be related to the fact that the resistance of the elements rises as they get hotter. PS There are lots of mnemonic diagrams about if you need a reminder of the formulae. https://duckduckgo.com/?q=voltage+current+resistance+triangle&t=ftsa&iax=images&ia=images

Purely as an example, you can find Paragon kiln diagrams at https://corp.paragonweb.com/support/kiln-wiring-diagrams/ There are three for the TNF233 (single/three phase and probably different controllers), showing differences in resistance and connectivity between elements. e.g. https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/Wtnf233.pdf BTW what is your mains supply? https://en.wikipedia.org/wiki/Mains_electricity_by_country Nominal voltage is 230/400 V, in practice 240/415 V is more commonly used.

A picture of one of Carlton's horns, and other peoples work (e.g. 4-headed drum, multi-chambered wind instruments, ...) clay musical instruments https://www.pinterest.com/baldaufa1/clay-musical-instruments/

https://ceramicartsnetwork.org/ceramic-recipes/recipe/Malcom-Davis-Carbon-Trap-Shino-143805# If the glaze ingredients are (partially) soluble it can cause troubles. 1) Ingredients that dissolve in the water are likely to finish up absorbed in the clay body, rather than remaining at the surface and entering the glaze melt. Maybe your recipe expected the soda ash to do this, but not the Nepheline Syenite ??? Expert opinions welcomed. <<< 2) If the glaze slop is subject the thermal cycling partially soluble ingredients can cause strange effects.

A nice idea, which triggered this thought. There may be some ideas on the use of gourd-size resonators in this book that could be implemented in ceramics. change location and currency for some local prices https://www.bookfinder.com/search/?full=on&ac=sl&st=sl&ref=bf_s2_a1_t1_1&qi=OAsKRPTKCBg9erQLq0pcohcePyM_1714219097_1:2689:6113 ... perhaps sometimes using mixed-media (e.g. the banjo-like instrument).

Can you confirm that you are talking about Amoco Palladium Glaze PC-04? Which seems to give a mirror-like finish by local reduction of manganese. As Callie has said you might try the ways people try to preserve reduced raku glazes, including wax polishes. I don't know if palladium luster gives a mirror-like finish. However as I believe that palladium metal is now even more expensive than gold I doubt that it's option worth exploring.

@neilestrick Could you comment on a couple of points. - 1) The kiln is rated at a maximum temperature of 1,240°C/2,264°F. What is a sensible firing temperature to give reasonable element lifetimes? 2) Fire safety. The manual states: Please only put this kiln on a heat-resistant worktop such as a metal stand, stones or ceramic tiles. Please note that the worktop should be very stable and be able to hold up to 30 kg of weight in total, for your safety. A photo in this advert shows the use of short legs/bricks. https://www.amazon.co.uk/Top-Loaded-programmable-Pottery-Projects-Beginners/dp/B0BZ53RXKM I assume that anything like this should be on a very fireproof/heat-resistant surface. PS @Moza Where are you intending to place the kiln while firing?

This looks like the manual https://kilns.pro/wp-content/uploads/2023/01/PC3L-User-Manual.pdf

An item on Amazon looks similar and has some stats. https://www.amazon.co.uk/Top-Loaded-programmable-Pottery-Projects-Beginners/dp/B0BZ53RXKM ... it includes

Your not alone there. White is just about the first adjective I think of when bone china is mentioned. It's an interesting idea that it might really be objectively bluish but subjectively "whiter than white" (like many detergents). The change from "whiter than white" to a more visible greenish tint then doesn't seem so implausible. Possibly due to some subtle change in the nature of the glass in which the (iron?) chromophore is embedded. From @Min's reference. PS a test-tile without Veegum seems an increasingly interesting idea. BTW how are small test-tiles for different body compositions usually made? Using volumetric mixing ideas from glaze tests would seem sensible if you need to do lots. Perhaps drying the over-wet samples on plaster or in plaster moulds - or applying as a slip to a biscuit tile (although that might make inspection more difficult). PPS Can you confirm that you have observed the green tint under several different lighting conditions. So we can exclude any light-spectrum related issues (c.f. neodymium glass).

Some plausible-looking advice on techniques and H&S referenced in: Historically there have been two sorts of lustres: reduction lustres and resinate lustres. Your comments seem to apply more to the reduction-fired reduction lustres. While tho commercial oxidation fired products are resinate lustres. Ever wondered why solder is often sold with a rosin flux running through it? When you apply it to the joint the hot rosin reacts with any oxide on the copper surfaces to form copper resinate. The resinates lustres are made by reacting metal oxides or salts with rosin and dissolving the resinate in or another solvent. With luck you finish up with quite a high concentration of metal resinate in the solvent. When these are fired they decompose leaving a thin metal film (and often some pretty nasty fumes). As Min said, do try and get in touch with @liambesaw if you can, but he hasn't visited the here since 2022. A friend used to run a garage industry making resinates and had very strong reservations about many of the solvents used in commercial lustres, sticking to - AFAIK - linseed oil. Manufacture a gold lustre is fairly briefly covered in "Pottery Decorating" by R. Hainbach. Which involves mixing "bright gold" with a bismuth lustre. Bright gold apparently containing resinates of gold and rhodium (and also possibly bismuth, uranium, chromium and iron?). Although a simpler wet process is also described for producing gold resinate from gold trichloride and resin-soap. ... probably much better to find out what people do nowadays. PS The book seems fairly expensive at the moment, change this search to your location and currency. https://tinyurl.com/2d783cv8

I meant a something like a normal bisque temperature, rather than the high-bisque used for bone china. In a hand-waving sense the more refractory ingredients wouldn't have entered the melt at that stage. OTOH the bisque nature of the test-tile might impede looking for the colour.

Any idea of the likely source? Or the likely level of contamination?

Starting a new thread with an eye-catching title such as "Why is my bone-china green?" would probably draw a wider audience. In desperation: - I cannot see how it could be a kiln issue, but can you get somebody else to fire a test-tile for you? - It also would be interesting to see how a low-fired test-tile came out.

Just to point out that your approximation does not allow for the volume occupied by the clay particles. That's what Brongniart's formula addresses.

Is there any US charity you can turn to for advice. (In the UK Citizens Advice might be worth trying.)

I think the usual form of Brongniart's formula will give you answer. This often uses a value of 2.6 for the density of "typical glaze solids". Which seems close to the density of clay particles. Particle Density https://link.springer.com/referenceworkentry/10.1007/978-1-4020-3995-9_406 Densities of clay minerals range from 2 to 3, but many are near 2.65 g cm PS An old but good ref for t-sig is Super-Refined Terra Sigillata https://digitalfire.com/article/super-refined+terra+sigillata ... but note that it doesn't mention the more modern deflocculants. ... the use of hydrometers has been replaced by weighing an empty and full calibrated syringe in many glaze applications ... it mentions several ways of concentrating thin t-sig, eg As another option, use a crock pot set on medium heat with the lid off. In either case, the rate of drying will depend on the atmospheric humidity and the mount of heat applied. It will take some experimentation to learn the ideal conditions. You may find a cheap crock pot at your local thrift shop. PPS Two threads on the use of Brongniart's formula for glazes "in the bucket". Including references to the formula and a calculator.

What body are you using?