[Clayart] Ivor's proposal

ronroy at ca.inter.net ronroy at ca.inter.net
Sun Mar 23 10:30:28 EDT 2014

Hi Doug,

Never measured that, mainly overall shrinkage only. Im interested in  
any results you are getting Doug - all grist for the mill.

I would say that a 6 inch bar would give you more accurate shrinkage -  
I use bars 6"x 1"wide by 1/2" thick.


Quoting douglas fur <23drb50 at gmail.com>:

> RR thanks for the tip.
> How do my other design assumptions sound? Specifically, that there is no
> shrinkage between black hard and bone dry.
> I've measured this casually and it seems to be so. What's your experience
> been?
> Seola Creek
> On Mar 22, 2014 3:51 PM, <ronroy at ca.inter.net> wrote:
>> I have done many experiments to find absorbency of fired clay (glaze
>> firing temperature) and have found even small variations in technique give
>> different values.
>> For instance I boil bars right out of a kiln so there is no atmospheric
>> water absorbed before starting. I noticed if the bars are hot I get
>> different results than if they are room temperature as they go into the
>> boiling water.
>> My standard test is boil for two hours, cool with cold water to prevent
>> evaporation while weighing, pat dry and weigh right away.
>> Let me know if there are questions about this - RR
>> Quoting douglas fur <23drb50 at gmail.com>:
>>  Ivor
>>> How does this method sound?
>>> 1) make a 10cm square cube, weigh and measure. 2) dry to black hard, weigh
>>> an measure. 3) dry in oven, weigh and measure. 4) bisque fire, weigh and
>>> measure. 5) saturate with water, weigh and measure.
>>> I think the differences in the first three should get the weight and
>>> volume
>>> of water of plasticity. 1-2= wt. and vol. of water to atmosphere. 2-3=wt.
>>> of water in pores and by extrapolation from the first step the volume of
>>> pores could be calculated. Steps 4 and 5 may be redundant but you could
>>> check the weight of water in the pores, check if there's shrinkage from
>>> black hard to bisque and get a weight for chemical water and l.o.i.
>>> DRB
>>> Seola Creek
>>> _______________________________________________
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>> Ron Roy
>> ronroy at ca.inter.net

Ron Roy
ronroy at ca.inter.net

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