PeterH

I got the page, and it says that the demo is at https://s3.amazonaws.com/nist-srd/ped_demo_5.1_setup_final.zip If you have any further problems PM me with your email address and I'll try to email it to you.

I assume that you intend to reduce both calcium & silicon, or is the amount of silicon involved a negligible fraction of that in the glaze.. I'd wondered if there was a trustworthy limit formula you could use, be interesting to see what it says.

Have you tried to measure/estimate the UMF of the glaze matrix rather than that of the matrix+crystals? It seems a more logical number to use with the Skull chart. For a high-calcium matt I understand that the crystals are calcium silicate, there are several to choose from but I'll assume 2CaO·SiO2. So do a line blend of your existing glaze recipe and one with rather less 2CaO·SiO2 (or its precursors). If you've straddled the just-no-precipitate recipe you have a good estimate of the matrix chemistry. If you didn't remove enough 2CaO·SiO2 you still have a closer bound on the matrix chemistry, and an idea how big the change in parameters such as flux-ratio are likely to be. PS - Obviously stick to a single cooling cycle. - Probably best done converting the UMF to a "recipe" of oxides. Subtracting some 2CaO·SiO2 from the recipe. Then re-normalising (i.e. calculate the UMF of the new recipe). - No need even to consider if/how you can make up that recipe from your original list of ingredients.

+1 drying between wall-board. In my limited tile-making efforts I also turned the slab+boards over from time. Re the use of silica sand, I found this a powerful analogy. PS I was taught that non-optimum rolling can make the slab more likely to warp: frequent turning & unsticking from the rolling surface, gradual reduction in thickness, rolling in multiple directions, don't let any thickness guides constrain the slab's edges, ....

Now lots available at £24 over here https://tinyurl.com/2p4k2jst

Can anybody explain the apparently white areas around the red line and dots

> I was looking for the trial version of the NIST? phase diagram software ... Just to point out that there is a time-dimension to phase transforms that phase-diagrams don't capture. A physicist might say that they are "thermodynamically correct", and only show what phase has the lowest energy under the given conditions. Saying nothing about how long the change of phase will take. AFAIK it's rarely of practical significance, although I suppose it's relevant when the timing/temperature of the firing becomes important: e.g slow-cooling microcrystalline glazes, nursing macro-crystalline glazes. The effect is spectacularly evident in the phase diagram of carbon. Normal temperature and pressure is about 1 bar & 300K. So every diamond you have seen is about 1,000 bar away from a point where it is "stable" ... and not much closer during the geological time where it was in fairly-near-the-surface rocks. PS https://www.whiteflash.com/diamond-education/diamonds-how-do-they-form/

Hard to argue with that, but I would suggest that they can help reduce the number of tests you need to make. For glazes that phase-separate (e.g. many mattes) the UML formula will not accurately reflect the composition of the different phases. Which raises issues of interpretation and limit setting.

It looks like this URL may show both sides of one of the 3 parts of 183F https://www.ebay.co.uk/itm/134337508508

https://digitalfire.com/material/petalite Petalite is a lithium aluminum silicate mineral (more simply a lithium feldspar) that is commonly used in clay bodies. It is valuable because it provides an insoluble source of lithium and has the highest Li2O:Al2O3 ratio of any natural mineral. Lithium is a strong alkaline flux and is effective over all temperature ranges. It imparts lower expansion and gives a unique color response to copper and cobalt in glazes. Some commercial versions have a chemistry that fairly closely matches the theoretical chemistry given here. Petalite is most prized for its mineralogical properties. It is especially valuable in imparting thermal shock resistance to clay bodies because it has almost zero expansion when heated above 700C. Bodies with 60%+ petalite can take a direct flame and rapid water cooling without failure. To make a plastic clay body mix petalite with as much ball clay as needed. For a casting body, use as much kaolin as needed to achieve the desired casting properties. Bentonite can be added to either type of body to increase the petalite proportion. One serious problem with low expansion petalite bodies is that it is very difficult to achieve glaze fit. All common glazes will craze. This is compounded at lower temperatures where the limited low-expansion silica and alumina necessary for melting raises glaze expansion. For some low-expansion bodies, it is almost impossible to match a glaze

Yes -- and it will probably be impossible to de-mould. ... although I have a very vague memory that I seen mention of a sacrificial "core" -- which burns-out/crumbles during the firing -- being used in some circumstances. Somewhat tongue in cheek, a picture of ancient Peruvian pan-pipes from https://digitalassets.lib.berkeley.edu/anthpubs/ucb/text/nap002-003.pdf My understanding of the paper is that the pipes were cast individually and then joined by adding additional clay by hand (although the set of individual pipe moulds for a complete panpipe were held in a common mould structure). Seriously, what is the intended usage of your end-product. It will enable us to understand the importance of the precision you seem to be demanding. It might also mean that the inevitable shrinkage & warpage of clay products during both casting and firing may render your product unusable for your intended purpose (a point already raised by Mark).

Any idea of the manufacturers code for this item? For example looking through https://img1.wsimg.com/blobby/go/a473195b-32be-4831-aad8-e122a50bcf46/IN THE KILN CERAMIC GREENWARE-BISQUE LIST.pdf gives ... but I failed to find more details on the site. Searching for 183F elsewhere give: https://bisquebusters.com/products/scenery-mountain-train-3pc A more general search found this, but without a manufacturers code https://www.ebay.co.uk/itm/134018515130

There are also a couple of Nigrosh's Egyptian Paste recipes under glazes. PS Googled site:glazy.org Nigrosh

Low Fire : OTHER Ways to Work in Clay Leon I. Nigrosh? If this is the right book 2nd hand copies seem quite cheap (<$5). https://www.bookfinder.com/search/?full=on&ac=sl&st=sl&ref=bf_s2_a1_t1_1&qi=jZ9txr1bouNCtZ9PoXMfx.wd7CM_1704364091_1:11533:21043

Are you trying to make a set of panpipes or a high-tech industrial component? It would help if you gave us an idea what you are trying to make, and the use to which it will be put. This gives the experts some criteria to judge the merits of alternatives production techniques. Two minor points. - If you use multi-part moulds don't draft-angles become irrelevant, although parting lines may require tidying. - Is extrusion an option?

I was fascinated by mainstream and "alternative" photographic techniques as a child. So some book knowledge and no practical experience with images on clay. What is the name of the process you are using? @blackthorn has been a/the major contributor to several threads on photo-lithography and other image transfer techniques. He seems to have tried many processes, often with mixed success, and the best results I remember are from a ink-jet printer based idea, mentioned in a weakly-related thread. In reply to your specific questions: There are several types of linseed oil (raw, refined, stand, etc.) and it seems like they have either recommended a particular type (all different) or just said "linseed oil". Some say to use gum arabic and others don't mention it. There are lots of process and gum arabic is used in at least two different ways. 1) Relying on the fact that oil and water don't mix. For example a very simple process of taking an image from a photo-copy. Photolithography on Clay https://pistrucciartworks.wordpress.com/2011/03/20/photolithography-on-clay/ 2) Using gum as the basis of a photo-emulsion, where the gum hardens when exposed and the unexposed gum can be washed away. [Having the same problems as newsprint -- limited tonal range and sometimes needing the use of half-toning.] Some process issues Trouble w/ Cyanotype on Bisqueware Discussion of three variations on the theme: classical cyanotype, gum bichromate and gum with masion stains. PS There are H&S issues with gum bichromate

Just my take on this. Certainly as a term "memory" has its problems, not least the implication of some sort of consciousness. However "local platelet alignment" is a real property, that can cause the previous history of the clay to influence its future behaviour. An effect that sometimes has practical significance. Techno File: Clay Memory https://ceramicartsnetwork.org/ceramics-monthly/ceramics-monthly-article/Techno-File-Clay-Memory# Crack H in Hamer & Hamer http://ceramicsfieldguide.org/pdf/materials-handouts/ClayCracks.pdf PS "Squeezing out water" may sometimes relate to changing platelet alignment so there is less inter-platelet space to hold residual water. A similar effect occurs during hard-panning, but in this case caused by excessive deflocculation rather than physical manipulation.

Tangerine ice Ruby Dust

I've no practical knowledge, so treat this all a here-say I'm interested in how you get on, but ... - I don't think either bones -- or seashells -- will survive high firing sufficiently intact to act as a stilt. - I doubt that bones will help form a "glaze" in the same way that seashells do. Firstly I think shells are used as a separator between the pot and clay wadding placed inside the shell. Shells seem a much better shape for this than most bones. Effective Side Firing https://ceramicartsnetwork.org/pottery-making-illustrated/pottery-making-illustrated-article/Effective-Side-Firing# While wadding is traditionally only used in atmospheric kilns to prevent pots from sticking to the shelves, it is necessary for side firing in electric kilns. Sea shells turn to powder (calcium oxide) during the firing, and will not support the weight of a pot. Using wads under the shells prevents the pot from falling onto the drip tray and sticking to it. Secondly the chemistry is different, perhaps critically so. Shells in Ceramics https://www.weloveclay.com/read/53007/53007/ Why then were shells not adopted more widely? Australian wood fire potter Owen Rye has pointed out that though ancient potters were keen observers of their craft, none could have understood or intuited the science of shell use. The shells themselves are formed from calcium carbonate which, when heated, converts to calcium oxide or ‘quick lime’, a powerful flux. In isolation, calcium is one of the most refractory oxides, only melting at 2572˚C+. But combine that calcium with alumina and silica and you have what is known as a ‘eutectic’ – a combination of oxides that melt at a lower temperature than they would on their own (in this case, a much more manageable 1170˚C). Why then were shells not adopted more widely? Australian wood fire potter Owen Rye has pointed out that though ancient potters were keen observers of their craft, none could have understood or intuited the science of shell use. The shells themselves are formed from calcium carbonate which, when heated, converts to calcium oxide or ‘quick lime’, a powerful flux. In isolation, calcium is one of the most refractory oxides, only melting at 2572˚C+. But combine that calcium with alumina and silica and you have what is known as a ‘eutectic’ – a combination of oxides that melt at a lower temperature than they would on their own (in this case, a much more manageable 1170˚C). All this means that on the interface between shell and pot there is a melt that leaves a shell-like scar on the surface of the clay. As the shells are stuffed with clay to prevent them from collapsing, the same happens on the inside. The core of the shell remains pure calcium, which is dry, friable, expands when wet and can be easily removed after the firing. An aesthetic bonus of using seashells is that they contain small quantities of salt. During the firing, this salt can volatilise, leaving a subtle halo of salmon pink or orange on lighter coloured clay bodies. Shells decompose into calcium oxide, bone eventually decomposes to a mixture of calcium oxide and phosphorous pentoxide, which may well prevent a suitable eutectic forming. Also bone ash tends to retain some of its structure, probably making both oxides less available for forming a "glaze". https://en.wikipedia.org/wiki/Bone_ash Bone ash is a white material produced by the calcination of bones. Typical bone ash consists of about 55.82% calcium oxide, 42.39% phosphorus pentoxide, and 1.79% water.[clarification needed] The exact composition of these compounds varies depending upon the type of bones being used, but generally the formula for bone ash is Ca5(OH)(PO4)3. Bone ash usually has a density around 3.10 g/mL and a melting point of 1670 °C (3038 °F). Most bones retain their cellular structure through calcination.

Oops, Should have credited Hyn Patty

+1 for starting another thread. I'm used to seing rather chunky rubber block moulds on the net. As from 6:53 in this video. How thick are you printing the walls? Would these rubber moulds be self-supporting when casting into them, or would they need a "backup" mould to prevent distortion? ... which I believe is common practice in some areas. How to Make Backup Mother Moulds https://www.aldax.com.au/backupmould.htm

I had a vague memory of possibly related postings using IR thermometers and/or IR cameras. Having been impressed by images such as this one showing an overheated relay lead. Turns out it was from one of your postings, What's your current position on these techniques? PS I also have a vague feeling that some mobiles were sufficiently sensitive to IR to give useful images.

Help, I'm having trouble understanding these figures. Problem 1. 28+23+28=79Aamps, but the 240V kiln seems to be rated at 60amps. https://www.sheffield-pottery.com/SKUTT-KM1231-3PK-240V-1PH-p/skkm12313pk.htm ... note that 79/sqrt(2)=55.9, so it might be interesting to know if the current sensor is reading RMS or not. Problem 2 Currents of 28+23+28 indicate that the centre section has a higher resistance than the end sections. But the ends seem to have 2x 8.9ohm elements in parallel, and the centre 3x 11.3 ohm elements in parallel. https://skutt.com/images/KM1231PK-1PH-and-3PH.pdf https://www.armadilloclay.com/uploads/5/1/2/8/51288343/element_resistence.pdf So, ends should be 8.9/2=4.45ohms & the centre=11.3/3=3.76...ohms. ... where the centre has a lower resistance than the ends ... and the currents are very high at 240*2/8.9=53.9amps, 240*3/11.3=63.7amps and 240*2/8.9=53.9amps compared to 28-23-28.

You may find these of interest if you are going to make your own paperclay. HOW TO MAKE PAPERCLAY | Chris Campbell http://www.ccpottery.com/colored-clay-lessons--chris/how-to-make-paperclay-.html Great if you have a heavy-duty mixed. If you don't you may have to resort to adding the damp paper-pulp to a pre-made thick clay slip, or adding dry clay powder to a wetter paper-pulp mix. In either case it will take longer to dry on a plaster slab due the the greater water content. Making Paper Clay Storage Easier and Less Stinky https://ceramicartsnetwork.org/daily/article/Making-Paper-Clay-Storage-Easier-and-Less-Stinky