: JBaymore - Viewing Profile

Body formulations with nothing supplying additional sources of fluxing materials to cause more of the SiO₂ in the clay components (both as trace admixtures and from the kaolin/metakolin silica ejection) to convert to a glassy phase. Depending on the firing range, if you don't see an addition of feldspar, neph. sy., frit, sometimes spodumene, or the like in the formulation..... there there is the possibility of the issues I mentioned.

best,


....................john

Be careful taking bodies with little devloped glassy phase (becasue of no spar, frit, or neph. sy. content .... yeah...spodumene counts here.....) up to higher temperatures above the 1100 C / 2012 F range........ particularily with longer firing cycles. They are prone to having the non-melted silica on the body converted to the cristabolite form of SiO₂ ..... which has a nasty huge impact on the COE of the body. Can cause dunting issues on kiln cooling...and also cracking in the domestic oven temperature range. The amount of cristobolite developed is linerally related to the time spent above 1100 / 2012.. ..... twice asl long... twice the conversion level.

Some of these above recipes would tend to have that issue, I think. Cone 6 is typically reached above that temperature for most typical rates of climb.

best,

.......................john

Welcome Anne. Glad you found us.

best,

.......................john

Chris Campbell, on 18 May 2013 - 08:26 PM, said:

What she said.

best,

...................john

Shirley,

I too learned to program in my Comp Sci classes in college using punch cards. Pain in the butt submitting them to the system administrator and waiting to see if the coding worked. I remember when we finally got acces to the teletype terminals. Yeeehaw!

The UMass mainframe took up a huge building. And of course us students tried to crash it .


Learned Fortran and COBOL and Basic.

Ah.... those were the days. But yes... you out geezered me.

best,

.....................john