Min

@AndreaK, lowfire and earthenware clay has been used for centuries around the world for domestic ware. How durable this particular body is would have to be tested, I know some of the lowfire talc bodies were very weak. In North America many potters have gravitated to midrange for various reasons, one of which is it's possible to have wares that don't leak or overheat in the microwave even if the glaze has crazing or pinholes and it's fine to leave the bottom of the pots unglazed. For lowfire (including earthenware for this conversation) in order for the ware to not weep / leak when used for mugs etc it is necessary to completely glaze the pot. (I do know someone who uses terra sig on the foot but that's another topic). A huge advantage of using lowfire / earthenware is the energy savings when glaze firing and the wear and tear on the kiln elements etc. Plainsman supplies really thorough info on all their claybodies. For Snow the link to it is here, click on each of the subjects and it will expand to give the details. For Snow the absorption figures are below. You can see that it has a huge absorption of 28% when fired anywhere from cone 06 all the way to cone 2. You can also see that the absorption doesn't drop below 12% even when fired to cone 6. What this means is there is never going to be enough fluxing of the clay to vitrify it enough to be leak proof without a glaze. Functional ware made from this clay will need to be stilted when glaze fired. From the Snow page (linked above) it looks like Spectrum 700 glaze fits this body well with Snow being bisque fired to cone 04 and glaze fired to 05.

If there is a colour shift it's likely to be minimal if at all.

As much of the density or mass in a firing comes from the shelves themselves it's often helpful to put the taller pots on the bottom shelf, shorter pots and more shelves in the middle of the kiln and tall again on the top shelf. (assuming it has with just one thermocouple or is a manual kiln)

I used to use a Talisman but switched over to using a cordless drill with a brush attachment and a regular plastic sieve that sits in the glaze bucket . WAY easier to clean up!!! Can clean the brush attachment in a small basin or pail of water or under a running tap. Takes seconds and no big sink needed. I have one sieve for clear and light coloured glazes and the other for the dark glazes. I sold my Talisman. To give credit where credit is due this idea is from @liambesaw

I have a Shelly bone china set from my Grandmother, it's at least 100 years old. I shone a (halogen) flashlight into one of the teacups, very translucent! However Shelly made their bone china I'm not seeing any green in it. (except for the on-glaze work)

That’s unfortunate. It will be a question of trial and error to find a commercial clear with low iron contamination to rid the glaze of the yellow tinge. At least from the info supplied in the link above you know which ones won’t be acceptable. Is mixing and testing your own glaze an option?

I would go back to square one and change just one variable at a time. Original recipe of 50 bone ash (one test with real and another with TCP) 25 Cornwall Stone (if @Jarman Porcelain doesn’t have any I think I have a small amount left that I can share) and 25 kaolin (grolleg). Mix that up dry then split into two and mix one batch with tap water (after flushing the tap for a few minutes) and the other batch with distilled water. At the same time I would run the same two tests with Veegum included. If these test show no green (or far less) then the field is narrowed down to something in the Cornwall sub being used.

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.

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.

This thread is a continuation of this one. Some comments regarding the green tinge on page 2 of that thread.

I'll try and split this thread into a new one re Green Tint Bone China. Arggg! I lost the initial post, I'm sorry but @Jarman Porcelainwould you be so kind as to you repost your image/post from your first post here? another edit: the split did work, it just took a while for it to go through. Link to new thread below, thanks for everyones patience! https://community.ceramicartsdaily.org/topic/41608-why-does-my-bone-china-have-a-green-tint/#comment-256771

Are you bisque firing the underglaze on before glazing?

What are you thinking is causing the green? Chromium or copper? Have you tried one of the recipes that does produce the green tinge with distilled water to see if it still goes green?