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tiles cracking..

updated wed 24 nov 04

 

nagy on tue 23 nov 04


hi all,

this is from nagy from Egypt
I have this job of tiles size 55x 35x 0.8 cms. "see illustration"
I use ball clay ( 10% grit added) since it doesn't rap and I glaze them=20=

as well after bisque fired, the total number is 52, after dried well (=20=

99% sure they were dry! that I lay them on plaster sheets to help=20
bottom drying for long enough so they stay flat).. I kept them in the=20
kiln on a 100=BA for 4 days to make sure that they are bone dry,,, by =
the=20
way I put them like books on a shelf I mean vertically next to each=20
other since they have an edge to keep space and allow heat to go=20
through....., then I fired them in my electric kiln to my normal bisque=20=

temp.

now comes the tragedy I only managed 19 pieces out of total which had=20
serious cracks but at least they came out as one piece,, the rest are=20
in either 2 or 3 pieces most are either vertical devisions and/or the=20
corners..... I know that there could be millions of reasons for this=20
result also know that if I took all per-cautions there is no guaranty=20
any way, but what I know most is that you people have solutions for my=20=

problem ,,,,

- I want to also mention that I tried to make sure that clay is well=20
compressed and mixed
- also thinking of changing the measurements to be same hight but less=20=

in width by putting the word rooms on top of the nos. since it might=20
help clay to stand the heat
- I am thinking of firing them stuffed horizontally rather than=20
vertically
- I haven't lost confidence in you or possibilities .

thank U in advance.. and don't worry about my depression I over came it=20=

already

nagy