PeterH

Only hand-waving, but I expect the importance of tin (and iron) in some copper glazes is because all three elements have variable valencies; and in the right circumstances can help redox reactions move copper from Cu(II) to Cu(I) or even Cu(0) -- and/or buffer it against oxidation once it's in the desired state. There is also Weyl's point that the presence of tin increases the solubility of metallic copper in a glass (or glaze), which can be important in obtaining colloidal copper particles. Woldemar A. Weyl Coloured Glasses has some interesting thoughts on the colouring mechanisms in glasses. Not cheap, but if you can borrow it on an interlibrary loan ...

I see that you are in Iran. Can you give us some idea of the materials you already have, and those you can get from your suppliers? Here are two handouts from a reputable source, using ingredients readily available in the USA. STA Decorating Slip https://www.vincepitelka.com/wp-content/uploads/2016/03/STA-Decorating-Slip.pdf Table and Explanation of Slip and Engobe Composition https://www.vincepitelka.com/wp-content/uploads/2016/03/Slip-Recipe-Chart.pd @YanaAsh Can you comment on the availability of suitable products/suppliers in Iran?

Not knowing what APM elements were I found a couple of references, which seem to emphasise Neil's point that they are intended for a rather specialised market. https://www.theceramicshop.com/content/1269/APM-Elements/ https://bigceramicstore.com/pages/info-ceramics-tips-tip85_kiln_elements_1

Sorry to keep posting, but you keep raising such interesting points. Some years ago they started ink-jet printing large porcelain tiles with soluble salts. Apparently gave some nice semi-marble effects and maintained the colour if you scratched it (as is wasn't simply on the surface). I think there were a few papers and patents published. Eye candy Water Soluble Metal Salt Effects https://www.pinterest.co.uk/ceramicartcommu/water-soluble-metal-salt-effects/ The Soluble Salt Ceramics of Mark Goudy and Liza Riddle https://www.veniceclayartists.com/tag/soluble-metal-salts/ Arne Åse - Painting Timelapse https://www.facebook.com/arneaaseceramics/videos/arne-åse-paiting-timelapse/1855860691328585/ Arne Åse - Paiting With Soluble Metal Salts https://www.youtube.com/watch?v=6RMAanwmmnI PS Sent you a pm

Remembering the occasional usefulness of pyrotechnic suppliers https://www.skylighter.com/collections/chemicals have both Strontium Nitrate and Barium Chloride at less than $8/lb (plus shipping). Stannous Chloride is AFAIK generally available but pricey (and probably purer than you need). Searching the US market from the UK isn't that easy, you might like to repeat some of these searches. tin (ii) chloride dihydrate (stannous) on ebay.com $77/500g Etsy.com probably has something, but my searches from the UK aren't really working googling stannous chloride pottery supplies gives https://shop.clay-planet.com/tin-stannous-chloride.aspx listing Stannous Chloride at $30/lb. Not sure if I believe it, but as Scarva list it as £35/500g maybe it is possible. googling tin mordant Stannous Chloride throws up a few offers for smaller quantities.

Long ago I knew a potter who used silicon powder (which doesn't out-gas) to produce copper reds. Finding a cheap(ish) source of silicon power may not be that easy. Rather restrictive googles such as silicon powder -carbide -dioxide turn up suppliers offering small quantities of ultra-pure powder at high prices. Searches such as pyrotechnic silicon powder seem to be more successful. Silicon Metal Powder -200 mesh $9.00 Per Pound . https://www.fireworkscookbook.com/product/silicon-metal-powder-200-mesh/ . .. as it's not out-gassing mesh size may be less important than for silicon carbide.

Stumbled across this: The Effect of Silicon Carbide Mesh Sizes on Copper Red https://glazy.org/posts/164731 ... note enlarge button at bottom RHS of image Don't like the colours, but some interesting comments in the text.

Change this search to your location & currency. Cheapest 2nd hand here is £232! https://tinyurl.com/2p4k2jst Does your country have an inter-loan library system? I've no idea if the sign-up ebook services or are real or scam., but a google for ash glazes phil rogers pdf turns up http://infinity.wecabrio.com/080198243X-ash-glazes.pdf ... and a thesis by somebody else on glazy https://wiki.glazy.org/uploads/default/original/1X/085b890dabdd507a348fdcc09e4247b954029145.pdf Posts for wood ash on glazy at https://glazy.org/?keywords=wood ash ... including a Stull Chart

Just a thought. If you are using solubles (e.g. copper sulphate) in a dipping glaze they may be sucked out of the glaze and into the body. One way of reducing this problem (and generating others) would be to use CMC to make a painting glaze, the contents of which would hopefully stay on the body.

I knew there was a version of Baggs & Littlefield that wasn't behind a firewall Go to https://ur.booksc.me/book/9078584/3dc696 and click on the button This (for me) downloads the paper in English.

If its of any interest: Chemically Reduced Copper Reds In Oxidation https://storage.ning.com/topology/rest/1.0/file/get/3158179980?profile=original ... IIRC fine-grain SiC is mainly sold for grinding (eg stone tumbling) Haven't seen this idea talked about ... ... and a longer review of that paper

Weakly related, and use at your own risk ... Aluminum Foil Saggars: An Easy Alternative to Traditional Clay SaggarsLearn a quick and easy way to create saggars! https://ceramicartsnetwork.org/daily/article/aluminum-foil-saggars-an-easy-alternative-to-traditional-clay-saggars/ Aluminum Foil Saggar Firing https://vincepitelka.com/wp-content/uploads/2019/04/Aluminum-Foil-Sagger-Firing-Ken-Turner.pdf ... Potassium dichromatic has long had a reputation for causing contact dermatitis (progressively sensitising uses). More recently its carcinogenic properties have heavily reduced its use and availability (shared with all hexavalent chromium compounds). Introduction to foil saggar http://www.marjonceramics.com/pages/Adobe/2022 Foil Saggar and Terra Sigilatta.pdf PS There was an article trying various copper-red glazes in foil saggars, which I cannot find at the moment. Perhaps somebody else has a link? If it stirs anybody's memory I think the tests were on extruded hexagonal pieces. There are some interesting comments in ... plus several references to comments by Norm Stuart (which I've been unable to find). His comment on ferric phosphate probably relates to this picture. My own query to Norm seems to relate to this

Let's hope it was just chipped when you dropped it. However if it pings it suggests there is a glaze fit issue. Maybe try the hot to cold test as well to see if its incipient crazing. BTW maybe try an indian-ink test for crazing as well (some crazes can be hard to see). ... oops don't know what you could use on a black glaze. Although I've seen white indian ink for sale. Interesting read, but don't like the solvent. Maybe try a white marker pen or a "non-cheapo" white watercolour paint (hopefully has a fine grained pigment). crazing/tenmoku/dmso http://www.potters.org/subject60993.htm I've been working on some tenmokus to fit my porcelain body and getting these glazes into the right expansion range is tough because they are fluxed with feldspar and whiting which have a fairly hi expansion. Then, we have to add a fair chunk of Iron which increases the expansion even more. If you add a low expander such as magnesia, crystals will develop unless you cool fast. So it goes! The other thing is "revealing" the crazing when it happens. Real tough to see on a dark, reflective glaze that is a tenmoku. So, I've tried some ways of bringing out the craze lines so I could actually get a handle of the "frequency" of lines. The finer the craze lines, the farther off from fitting. OK, to the point! I've been using a mixture of DMSO and talc. Brush it on the finished piece and wait until it dries, wipe off, and check thru a magnifying lens. Bingo! As many of you know, DMSO is a very powerful penetrating solvent and it moves the talc right down into the craze lines and you will then get a perfect visual of what's going on in terms of glaze fit. I just inspected some tiles today that have gone thru the freeze/boil test and the two week soak test and, at last, I think I have a tenmoku that fits .. I've no idea what the two week soak test is. A word of caution: DMSO is indeed a tremendous solvent. It is also capable of penetrating the skin and carrying anything dissolved in it (that's dissolved, not suspended, like talc) into the body - so be careful, wear rubber (nytril) gloves when using it. .

Wonderful stuff. Although it had a limited ability to fit compound curves. greatly exceeded by the pad process. I must confess to being interested in the tissue printing process, as well as the tissue itself. Can you add anything to the discussion in this thread?

Presumably a boiling water:ice water test would increase the stresses and reveal latent flaws. BWIW - Boiling Water:Ice Water Glaze Fit Test https://digitalfire.com/test/bwiw ... note that for shivering you want to test cold-to-hot. This test subjects the clay:glaze interface to a differential thermal stress of 180F (112C†) both hold-to-cold and cold-to-hot (the former accelerates crazing and the latter shivering. This test is needed because, although ware may appear OK when first removed from the kiln, over time less-than-ideal fit will reveal itself. Compatibility between the expansions of clay and glaze are critical, not only to the integrity of the glaze layer, but also functional ware strength. Crazed glazes also provide a channel for water absorption by a porous body (creating conditions for the harboring of bacteria). Shivering glazes can drop chips of razor-sharp glaze flakes into food or drink. † I assume this should be 100C Some people use a more severe test: freezer-cold to boiling water. thermal shock test on mug... results http://www.potters.org/subject09036.htm ... especially Ron Roy's posts

The manual is here, but it doesn't seem to say much on the topic. The CINK User Manual https://cdn.shopify.com/s/files/1/2430/4931/files/CINK_User_Manual_-_Orig_04_2022.pdf?v=1654037145 p10 p12

Just to get things started ... It's a form of offset printing called pad printing. Basic idea is to form an image on a plate, pick it up on a flexible pad, and transfer it onto the target. https://upload.wikimedia.org/wikipedia/commons/transcoded/7/70/Cetakan_Pad_pada_barangan_seramik.webm/Cetakan_Pad_pada_barangan_seramik.webm.720p.webm More details at Pad printing https://en.wikipedia.org/wiki/Pad_printing The machine you showed does colour printing using several pads, one for each colour. PS If you were thinking of a manual DIY process, some of the issues would presumably be: 1) Making the image plate (probably a photo-engraved plastic printing plate?). 2) Cleanly inking the plate for each transfer. 3) Making the silicone pad to fit your target ceramic object. Video of casting a pad at https://youtu.be/VN0hESxwxXk No details about the ingredients. No idea if the vacuum chamber is optional. 4) Cleaning the pad after each use (I assume that the image registration achieved by the automation means this isn't needed for factory equipment). 5) Clean pickup of the image on the pad. 6) Clean transfer of the image onto the target object, and clean removal of the pad. 7) Choice of a suitable "ink" for your purpose. Maybe not that different from the ones used in silkscreen printing onto ceramic. 8) As you are transferring a 2D image onto a 3D object via a shape-shifting pad you may need to pre-distort the image so that it looks right on the object.

Looking at an old book that gave nice copper green test tiles at 1%, 2% & 3% copper oxide in a cone 04B base glaze (lead bi-silicate 65%, whiting 10%, potash feldspar 15%, china clay 10%). It said that if you don't want to use lead substitute borax frit for the lead bi-silicate. No pictures of the result though. Consistent with the route you seem to be taking, and the fact that the high-boron cone 6 glazes seemed to give more promising greens. I'm a little surprised at the high Na.

Might be of some assistance. need help with laguna pacific wheel http://www.potters.org/subject77125.htm PS One for the Sod's Law encyclopedia David had fixed his so I gave him a call. Said that there are two set screws in the same hole. One on top of the other. The second serves the purpose of keeping the first from backing out on it's own

Looks rather like a low-fire lead glaze coloured by copper. Their use by craft potters has largely been phased out on safety grounds (at least in those counties I'm most familiar with). Are you familiar/happy with using lead glazes? Do you have a recipe for one? PS This 1999 posting reflects the historic movement of craft potters away from the use of lead. http://www.potters.org/subject22065.htm PPS Digitalfire, usually a comprehensive source of pottery information simply opts-out of giving advice on this topic. Lead in Frits: The Hazards https://digitalfire.com/hazard/lead+in+frits%3A+the+hazards Lead has been used in ceramics for thousands of years because it works so well, that is, leaded glazes melt at low temperatures, have low thermal expansion, dazzling colors and tolerance to variable firing. Frits are a modern development that have dramatically improved the safety with which the material can be handled. Notwithstanding this, leaded frits are difficult to obtain in recent years. Generally most leaded frits were thought be fairly insoluble and safe to use as raw powdered materials, however recent findings about the disproportionately large effects of low lead levels call this into question. In addition, the glazes they produce will be as leachable for a given lead percentage as if the lead came from raw lead carbonate or lead oxide. There is a huge range of lead content in frits, some may have 1%, others 80%. To create a safe leaded glaze you need equipment to measure leaching of lead and expertise in ceramic chemistry to find the oxide profiles that release the least amount of lead. Therefore we are no describing any safer ways to use lead here. Please check the reference links on this page.

I may be misreading your question, but: Casting slip needs to be cast in a porous mould (typically plaster) which sucks the water out of the slip. A press mould typically has a sheet of rolled out plastic clay pressed into it. The porous nature of many press moulds helps the pressed item dry (and hence both firm-up and shrink away from the mould). What is the name (or recipe) of your porcelain slip, and can you explain what you are trying to do in more detail?

I doubt it, but am not in a position to know. However you would only be using it to seal the unglazed edge of the collar, which would presumably not be in contact with the soil. Minimising any opportunity to leach.

Copper in lead glazes gives a very characteristic deep green that was very popular when the use of lead glazes was common. Lots of it about in my youth in the `50s and early `60s, mainly in older buildings. Sadly there seems to be no lead-free equivalent, for technical reasons. 1) The colour is explained by "crystal field theory". See The Origins Of Color In Minerals http://www.minsocam.org/ammin/AM63/AM63_219.pdf 2) In hand-waving terms the glass structure adopted by the lead ions leaves spaces into which the copper ions fit which distort the energy levels of the copper's electron orbitals. This distortion results in a green colour. Pedantically orbital-hopping electrons remove quite a lot of reddish light from the incident white light, leaving a green colour. 3) I believe that only lead (and lots of it) creates the environment where this happens. There remain lots of green copper glazes. From Copper in various cone 6 base glazes (Free Online Glaze Class Pt. 8) https://tinyurl.com/mrxx2ycu Perhaps this area might be of interest. ... but hard to tell without seeing actual examples.

Perhaps relevant: Outdoor Weather Resistant Ceramics https://digitalfire.com/article/outdoor+weather+resistant+ceramics This is a common sealer available at a hardware store. I have dipped the terra cotta tile and it has dried. The surface of the dipped portion is smoother and has a slight sheen. That is the price paid for sealing the matrix against freeze-thaw spalling.

Can you give us a recipe for a typical glaze you use? To give us an idea of the sort of materials you use, and because the colour generated by metal oxides can depend heavily on the base glaze used (especially copper). From Copper in various cone 6 base glazes (Free Online Glaze Class Pt. 8) https://tinyurl.com/mrxx2ycu PS Still remember the spectacular dark green copper-in-lead-glaze tiles in public buildings in the '50s and '60s.