best practice for chip resistance?
Posted 15 December 2012 - 12:39 PM
Kiln Repair Tech
Owner, Neil Estrick Gallery, LLC
Posted 16 December 2012 - 04:24 AM
I agree with Neil about your design, avoid thin, narrow necks, pointed, long and unbalanced horse heads. You can also finish the bottoms smoothly so they will glide. A well made cloth surfaced board, in dark velvet or felt can help avoid breakages and make the set appear a bit more elegant.
Amaco's 'White Art Clay No. 25, Talc Free' has a cone firing range of cone 05 to cone 3 (1911°F-2138°F).
The bisque ware temperature is cone 04, 1971°F. The recommended glazes however are low fire at cone 05 (1911°F)
Porcelain #65 is very sturdy. It is a good idea as Amaco suggests to fire the bisque at the high end of cone 04 (1971°F) for glaze application. At 2205°F, you will get a very good product that is compact and dense and 'rings' on thin pieces when thumped. The Amaco glaze choices are also quite remarkable at cone 5-6.
Posted 16 December 2012 - 08:25 PM
#65 Porcelain is considered a midrange clay body and has no ‘range of firing’ it is a cone 5 clay. The glazes you can use mature at cone 5 or less but be sure to bisque fire to cone 04-1971°F. It does make alot of difference for glaze application. Be sure to test.
If using another company’s glazes, test, test and test to see if they are compatible with the clay.
Please if this is not clear, please say so and maybe I can or someone else can explain it better.
Posted 17 December 2012 - 03:39 PM
I also made small Sake test cups just like Amaco's test vessels however I made them with small troughs and a sprig to catch and watch the flows. I concentrated the 3 heavy coats on the inside of the vessels until I understood the nature of the glazes. I used two or so coats on the outside but feathered up from the foot.
I bisque fired to Cone 04-1971°F and glaze fired to Cone 5-2205°F. Be sure to read the labels on the glaze jars some of the glazes say fire 'at Cone 5-6'.
I did fast fire the glaze load because the bisque fire was so high and was only 234 degrees from the mature glaze temperature.
If you do what Amaco suggests you should have success. They even provide a picture to show how to load up your fan brush. Don't be timid about the application. I had no excess running but still be sure to kiln wash your shelves just in case.
Posted 20 December 2012 - 04:50 PM
Posted 21 December 2012 - 02:40 PM
Whistling Fish Pottery
Posted 21 December 2012 - 11:33 PM
If people want unbreakable chess pieces, they can buy ones made from metal.
Don't forget the aesthetics of the object. Why would people buy them ? because they are beautiful or because they are rock-hard? People who buy chess pieces made from glass or ceramics know what they buy.
By nature ceramic objects are breakable if you mistreat them, no need to cripple your style to make them harder. As you say, they hold up fine.
In all probability the chess pieces will get lost long before they break.
Make a few extra pawns.
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