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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).

The two photos are from Luxurybonechina.com and narumi.co.jp. A link to another photo is here: https://simple.wikipedia.org/wiki/Porcelain#/media/File:Transparent_porcelain.jpg I get the sense a greenish tinge to bone china is not so unusual. The green of the piece @Jarman Porcelain posted is tilted away from a yellowish I would expect from iron, but not so much to make me think iron’s not primarily responsible. The clay body is a hair’s breadth from being a glaze at maturity (the ultimate clay/glaze interface: the pot is the glaze). Grolleg and Standard both have over 0.5% iron in them, perhaps that’s enough to show when it’s all in the melt? NZK has half the iron of those two, so I don’t know. I found this interesting, since I feel like I hardly know what I’m talking about: https://www.jonsinger.org/jossresearch/tjiirrs/017.html I certainly imagine getting some into a reduction firing, being able to compare, would provide useful information.

Hi folks, we covered this a few years ago, but I was mixing glazes yesterday with my plastic bucket sieve, and a brush to run the glaze through the sieve into a spare bucket, and then back into the rinsed out original bucket. I have often wondered about buying a Talisman sieve, but in the long run the cost scares me away, and I really get along fine with my bucket sieve. I will pick up a digital scale as the cost of them has come down. QotW: Talisman, Bucket or other type of sieve for glaze mixing? bestg, Pres

Spectrum glaze sells dipping at least 5 gallons and it is too expensive just to try with shipping. If it doesn’t work I waste 400$. So couldn’t have the chance to try.

Did you try the Spectrum glaze that was mentioned in your other post about the yellow tinged glaze? https://cdn.shopify.com/s/files/1/0039/8177/0841/files/105-LFW_Glaze_Rec.pdf?v=1674848426

Do you think there is a link between the Veegum and the bone ash or TCP? (Veegum being magnesium aluminum silicate) Interesting read here https://www.researchgate.net/figure/Concentrations-of-phosphorus-pentoxide-and-magnesia-in-Roman-emerald-green_fig1_277089354 possibly linking the two with a green colour.

Hi @Biglou13 A flameware body would be your best be for this. 500F is pretty hot for a clay dish, especially since you'll be dropping wet, room temp dough onto a hot, flat surface. It's a lot to ask of any clay body besides flameware. The other option is to just buy a cheap cast iron dutch oven on Amazon. It works great, and you don't have to worry about it cracking. My dutch oven is preheating in my oven as I type this! My loaf from last week. 25% whole wheat, 80% hydration:

This isn't the exact box that I use, but pretty darn close. It has served me well for the past 8 yrs. ArtBin Betty

Oh yes, I've done both actually. The bisque looks normal, a slight pinkish hue, but less pink than my halloysite porcelain. No trace of green. I've looked at cut samples of bisque and vitrified pieces under magnification up to 80x, I can't see anything green.

Hello, I’ve been working on a few apps for the last 5 years and I thought you guys may appreciate them. Blazed is an App that manages your Kilns, Logs, and Programs. It also lets you collaborate on your logs with anyone you choose to share with. Potfolio is an App that manages your Materials, Recipes, and Artwork. On the surface, you probably could compare it to a glaze calculator, but I think of it more as your own personal studio assistant. I’ve shared the links to download them from the App Store below. But if you have any questions I’d be happy to answer them! Tanner Blazed: https://apps.apple.com/us/app/1595514944 Potfolio: https://apps.apple.com/us/app/1528857080

I wasn't successful getting the gold to reduce with just pine resin, if you buy Greg Daly's book "lustre", he details making it from elemental sulfur and gold chloride. This works well. Commercial lustres using pine resin thinned with toluene use a different gold salt, I'm guessing that's the reason they work. I think the compound is a chlorohexanoic salt of gold. You'll also need a bit of bismuth in there to act as a flux bridging the gold and glaze. I had some luck making a silver lustre by making silver soap. Silver decanoate. But it was difficult to dissolve in almost everything so it was a pain to apply. Was conductive though and I made a few touch lamps using it. Also had success doing a similar thing with copper.

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

When I was a student I used a metal lunchbox-still have it.easy to clean and when open it was easy to access

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.

I have had it fired in different kiln, all the same result. I have occasional access to a gas firing, so I'm going to ask if they can put a test into the next firing for me. It might not shed any light on this, but more data is always good. What do you mean by a low-fired test tile? I've certainly seen it in bisque a lot, but I assume you mean something else.

If this were the case you'd see this in commercial bone china as well. I'm using NZK, Grolleg, Standard Kaolin, Veegum, bone ash, silica, frit 3110, and Neph Sye. Those are all materials used in industry, and are all noted for they exceptionally low iron content. As I said in the other thread, I'm not ruling it out, but it seems extremely unlikely as this oddity is apparently unique to me, but none of my materials are. I'm also sieving the slip, as well as running high powered magnets through it to remove even more iron (something industry also does). My suspicion is some kind of crystalline silicate of calcium is forming, the body becomes very fluid in the kiln, and the body has an absurd abundance of calcium. It could either be green in colour, or blue in colour and then giving green when light passes through those molecules and the yellow we all are used to from oxidation firings. Again though, the problem I'm facing with this explanation is much the same, if I'm getting this, why does it not occur in other's bone china? I plan to make a small batch with distilled water, hopefully this week if possible, that seems like a very worthwhile avenue of exploration.

Try sending @liambesawa pm asking about this. He hasn’t been on the forum for ages but when he was he was making lustres.

If it was iron I would hazard a guess we would see this more frequently. From my searches I haven’t been able to find any other cases of it. I find it very puzzling, wondering about colloids and phosphorus and the water used.

The sharing that goes on here is even more valuable than I had realized. I am the lucky pottery who met up with Mark in St. Louis a week ago. I knew I had absorbed a lot of his tricks of the trade from this site, but I did not fully realize how much. As we talked for an hour or two in my booth, almost every aspect of my pottery has some mark of his influence. From the way I wax my pots to the design of my display shelves - Mark's influence and generosity are everywhere. Helpful potters like Mark and Neil E. deserve a lot more credit than they get.

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

Hi guys, I'm new here, I seemed to come across this forum a fair bit when researching things so figured it was about time I signed up, its given me some pretty useful tips over the last year or so. Happy to give back what I take, I have more of a technical history than ceramics but there's plenty of overlap. Anyways, my first post I'm looking for a bit of guidance on creating my own gold lustre, there is very little information floating around the Internet and any books I've purchased are more geared towards using lustres than making them so I've been fumbling in the dark. Now I know commercial lustres are available but I have a working project that requires me to make my own to give provenance to the finished piece Now as far as I can work out a gold lustre is simply either elemental gold in a nano/powder form or gold chloride mixed with a carrier oil, lets say pine oil, would this be a correct assumption? I would then use toluene, turps or similar to thin this to the right consistency? Would I pretty much just mix say 10-15% gold with the oil, then boil to ensure it mixes well? I already have some experience in refining gold and do have the necessary nasty chemicals to produce my own powder or chloride so its really just the last step that im fairly vague on Thanks for any input, like I said, information on the process seems very patchy, even a pointer to a decent technical book would be appreciated.

A quick glance tells me Iron in oxidation sums it up.. See other thread for more details.

Support for the pyroplastic clay seems the name of the game.

If I were to guess I would say this may have been caused with dry solder joints, as small cracks appear on the solder ring around the component pin it begins arcing If I were to guess I would say this may have been caused with dry solder joints, as small cracks appear on the solder ring around the component pin it begins arcing and eventually burns the whole joint out. But as you mentioned, its quite tough to see the tracks in the image, if you can give a clear image of both the top and underside of this PCB I would have a better idea on what actually popped. In electronics you will find most PCB designs have common weaknesses and if you replace like for like then chances are you will find the same fault reoccurring eventually. If you opt to replace this whole board then I would recommend giving all the solder joints (Especially the burnt one) a reflow with some good quality flux cored leaded solder.

There is a ton of things that could cause this but the most intriguing part is you mention the kiln draw is half its rated value. Power draw conversion to heat is very predictable so if one metric is wrong then all will be wrong. Depending on how the elements are wired you may find only half are actually doing their job. If you can access where the actual wiring harness attaches to your elements you should check here first, the AC vibration will easily loosen these connections over time. Next could be faulty/aged contactors. If I were in your position and you don't know much of the history of the kiln I would just go ahead and replace the elements and any contactors in there, these would be the number one cause of low power draw, as these both have a lifecycle then its wise to start your own journey with this kiln with the clock/count at zero.