Porcelain vitrifies more than most clay bodies and will stick to itself or to the kiln self which causes spalling, chipping, on the foot or anywhere two pieces touch like on lids. This will also happen on other smooth, vitreous bodies. In California we have a clay body called BMix which, when it does not have grog or sand, will chip too without the alumina barrier. Earthenwares rarely get sticky enough to have to use it.
Hi Sir, couple of questions. Is there any difference between each and every wax resist to combine with the alumina? Is the reason for coating a layer of colour wax above the wax-alumina mixture to prevent the glaze from running onto the alumina? Appreciate your advise. Thank you.
Any ceramic wax resist will work. Do not apply this to anywhere there will be glaze. I add food coloring to the wax to see it better when I apply it and the color burns away. If glaze runs onto the wax/alumina it could be rough to the touch after the firing because the alumina does not melt. The alumina/wax is to prevent porcelain from either sticking to itself as on a lid or to the kiln shelf. This is only necessary at high temperatures for porcelain. Good luck
@@richardmccoll9297 What is the propose of the regular wax resist that is applied? I can see doing that if you have yet to glaze the pot. I was thinking of applying the aluminum resist after glazing but only on the bottom, in which case the regular wax resist is not necessary.
Hello, You may find some wax resist products will work better than others. I put a line of regular wax above the wax and alumina to keep the wax/alumina from touching the glaze transition. If it touches the area will be rough like sandpaper.
It just brushes off. Be careful to wear a mask when cleaning the bottom. Also some may stay on the kiln shelf which is easily removed. I save it and reuse the alumina. Just be careful not to allow it to touch glazed areas of your pottery because it is so refractory it will make it rough like sandpaper to the touch. Enjoy!
@richardmccoll9297 Thank you for replying! I'm waiting on my glazed pieces to dry then I'll add the alumina and wax mix to the unglazed bottoms. I've wiped off any glaze that is near the bottoms and kiln washed my shelves. I'm excited to do this. I'll be sure to wear a mask when outside cleaning off the bottoms after firing. Thank you!
Be careful to not have the alumina/wax mix touch the glaze. Just put it on the bisque where the foot touches the shelf or the lid touches the body. On lids I usually only need to apply the mix on one side so I put it on the pot body side so the alumina will not dust down on the glaze below.
@richardmccoll9297 yep, got it. My pieces have flat unglazed bisque bottoms. No glaze near them at all. Their bottoms will be coated with the solution and kiln shelf will be dusted with alumina as well just in case.
Not enough to make a difference. I have never noticed any contamination. The main concern is not to have the wax/alumina directly next to and in contact with the glaze because it will make the spot it touches rough. Glazes are composed of Silica, Alumina and a flux so if a little gets into your glaze it shouldn't effect it. Thanks for the good question.
I am not clear on what you want to do. Stainless steel is not used in ceramics and fired together unless they are glued together after the clay is fired. Wax resist is used to prevent water soluble materials, like oxides and glazes, from adhering to the bisque or green clay before the clay is fired. To achieve a metallic surface look into lusters which are fired onto the surface of glaze fired clay in an additional firing to a low temperature, about cone 018 to 017. Thanks for the question and good luck on your creative journey.
