Min

I recently changed to Hostinger too. I thought they really pushed the email function, I didn't sign up for it and probably never will, I saw it as a way to tether someone to stay with them.

+1 I think it's from copper carb in a high barium base glaze.

My hunch would be the difference in cation exchange rate. EPK is 4.5, I don't have one for 6Tile though, do you have that info Jeff?

There was a forum member here years ago who did electroforming with copper. Look up @Bob Coyle, there are links to his gallery page plus ones where is discusses his process. https://community.ceramicartsdaily.org/gallery/album/590-electroformed-ceramics-and-forged-metal/ https://community.ceramicartsdaily.org/topic/4229-anyone-else-doing-electroforming-out-there/

Hi Jacquie and welcome to the forum. Are you going to have control over the firing of the busts? Have a look at the drying and firing schedule Beth Cavener Stichter uses as a very safe firing drying and firing schedule. (note she goes to cone 2 though and drying the clay out is included in the schedule) What you are aiming for is the evenness of the drying to prevent stressing the clay and getting cracks. I know Toronto can be really humid in the summer, whether it's humid enough for the busts to reabsorb moisture from the air enough to make a difference in the firing I don't know. To be safe you could candle them overnight. (hold the kiln at a low temperature for 12 hours or so) Beautiful work!

If the base or foot of the pot is not glazed (usual practice for cone 6) then water is going to get into the claybody very easily through doing the washing up. When moisture gets into the claybody and the pot is heated it will cause the moisture within the clay to expand which in turn will craze the glaze. (it also makes the pot get extremely hot if microwaved) It's easy for oils, liquids etc to get into the porous body via the unglazed portions and the craze lines and go rancid if the clay isn't vitrified. If you will be firing to cone 6 then look for a body that has less than 2% (or even 1.5%) absorption. I don't live in your part of the world I so can't make a personal recommendation on what is available where you are. You could post a question asking for recommendations. @Pres, I think you are in the same area as the OP, do you have any you could recommend?

That clay has a posted 7% absorption rate when fired to cone 6 because it doesn’t mature until cone 10. This means it’s immature at cone 6 and will probably weep/leak. If you are making nonfunctional work it might not be an issue but the clay also won’t be as strong as a mature body.

Could you post a picture of the discolouration? Sounds like the clay is fluxing to the alumina? Are you firing over cone 6? Probably. There is kiln wash and then there is the good kind of kiln wash. Link here discussing various ones. I prefer the high alumina content one of 50 alumina hydrate, 25 epk, 25 calcined epk.

Hi and welcome to the forum. In general ceramic body stains (Mason or other brands) are made to be used to colour porcelain. Like anything in ceramics when trying something new run some small tests first. I don't know how much you know about stains but there are a group of body stains formulated for adding to claybodies rather than glazes. Glaze stains can also be used for bodies but there are some that won't work well. Have a look at the Mason Reference Guide, stains with a number 1 beside them are suitable for body stains. Are you firing to cone 10?

A tiny amount of chrome plus cobalt can make a really nice teal colour in washes, slips and glazes. @rabbethouse, have a look at June Perry's Wash Recipes, lots of good wash recipes. They are written for cone 10 but if you swap out the feldspar in a recipe for gerstley borate or Ferro frit 3134 or 3124 they should work at cone 6. For lowfire you would need to increase the amount of g.b. or frit. http://johnbrittpottery.blogspot.com/2013/03/june-perry-oxide-wash-list.html

Any idea hot you will be firing the kiln? High fire (approx 2400F / 1300C) is common for ash glazed wood fired pots. It's easier to get ash to melt at high temperatures than mid range. For any glaze there are three main components, silica, alumina and flux. Colourants are added to a base glaze. You have sources of sodium and magnesium listed, those are fluxes. You have wood ash which can be used to make a glaze, this has fluxes, which amounts and what oxides depends on what was burned, usually contains a lot of calcium. You have local clay which will be a source of alumina and silica (amongst other things). You have colourants copper and iron. It's going to take work to figure out how much of each to use. Have a read of Derek Philip Au's "Ash Glazes" to get started.

Rub 'n buff ebony is another product that might give you the look you are going for. https://www.amaco.com/products/rnb-ebony-carded?ref=2&taxon_id=325

I'm not comfortable suggesting a two section firing schedule but will throw one out there for a three section schedule. Please don't think it will be spot on without testing and possible altering as kilns don't all fire the same, this is just somewhere to start. You could do the first section then restart quickly without loosing much heat. Cone 5 glaze firing schedule in C with a hold 65 an hour to 120 no hold 200 an hour to 1045 no hold 42 an hour to 1177 hold for 10 minutes

I think we are overcomplicating this. If glaze is fine then don't mess with the TC offset. If bisque is under-firing then either fire to one cone hotter if using the preprogrammed schedule or increase the final temp like Neil said. Given that ^07 is barely bending and you are aiming for ^06 then try firing to preprogrammed ^05. Approx 30C between 07 and 06 and 06 and 05.

If you can only put 2 ramps how about right after the kiln finishes the 2 ramps then quickly reprogram it with the following 2 ramps. Are you wanting to just get to the max temperature then shut the kiln off or do you want to do a soak/hold at the top temperature? Kiln off after that?

Liner glazes can dry completely if you don't apply another glaze overtop of them. But, to apply one glaze overtop of another you want to get the second (covering) glaze on the pot as soon as possible to prevent the lifting you are getting. Don't wait until the underlying glaze is completely dry, do it as soon as possible The thicker the glaze layer the higher the chance of peeling or lifting of the previous glaze. It is possible to layer glazes thickly if you add gum (or Magma) to the glaze. Gums help harden and bind the raw glaze to the bisque. Watch you don't get the glaze layers too thick though as this will lead to crawling during the glaze fire.

I believe that in the UK frits are often named in a similar way as glaze recipes are. That is to say the frit or glaze is named according the preponderance of a certain oxide within it. For the calcium borate frit referenced in this thread I would hazard a guess the OP is referring to Calcium Borate Frit which has the chem in the chart below. Given the very high amount of boron in this frit it will take some tinkering to adjust a recipe using another frit. Back to the question of where to start with glaze calculation my suggestion would be to get to know glaze materials and what the contribute insofar as oxides and qualities.

https://ceramicartsnetwork.org/ceramics-monthly/ceramics-monthly-submissions/ceramics-monthly-submission-guidelines#article-3 https://ceramicartsnetwork.org/pottery-making-illustrated/pottery-making-illustrated-submissions/pottery-making-illustrated-submission-guidelines

Hi Rachel and welcome to the forum! Not everybody uses the book of faces so it might be an idea to do a screenshot of your images there and put them in your thread here. How soon after the first layer of glaze went on did you brush on the other glazes? Not sure I'm following this bit

If you use a claybody made for tiles it will be far less plastic than your typical claybody, less plasticity in a claybody helps tiles stay flat. (along with the practices you are already doing and @akilpots suggestions) Also, if you lay a piece of very thin plastic sheeting/film over the clay before pressing the cookie cutter down it will round over the edges so you don't need to smooth the topside eges of the coasters.

Hi Alan and welcome to the forum! I'm going to move your thread over to the Equipment section as your kiln building questions would be better suited there.

Which boron frits do you have available to you? If you aren't sure which frits contain boron look for ones that contain "B" or "B2O3". What is the recipe you have now?

Complexity bias is definitely a real thing but it's hard to avoid sometimes! If I had your kiln I would leave both the bottom air inlet plus the exhaust port open during a glaze fire until you get a bit hotter than you did at 600C, If your glazes turn out wonderful with shutting the inlet and exhaust port shut at 600C then great but what you are trying to avoid is deterioration of the elements due to gases/fumes from the glazes attacking the elements so they last longer. Are you okay on how you bisque fired? What type of clay are you using and what was your bisque procedure?

Laguna MS29 is another nice commercial midrange clear.

I'm not familiar with your kiln, does it have a vent? Could you post a picture of the "air inlet port" and the "adjustable exhaust port"? Sounds like these might be functioning as what we on the other side of the pond use spy/peep holes for? (apart from using to see cones) People have different opinions on when an electric kiln glaze firing should be closed up during the firing. For my kiln (without a vent) I close the peep/spy holes up at around 750C. Congrats on your new kiln!