Need more combustibles

After looking at the clay mix and poking around some more on the 'net, I've decided I need more millet / sawdust, jute or maybe even sisal / hemp.

An article I found indicates that 28% sawdust by weight. I also gives a number I have not seen before called "apparent porosity". This is a quantification of what I was doing visually by comparing my mix to the the IFB (insulating fire brick) my kiln has in it. That article says the apparent porosity is about 70%. 

Apparent Porosity (%) = {(Soaked Wt - Dry Wt) ÷ (Soaked Wt - Suspended Wt)} x 100

A quick read on this is that it's determined by by sectioning a piece of material weighing it dry, soaking it in water, then weighing wet, then pulverizing it and putting into a suspension with water to a specified volume (which I am still looking for right now). So, basically it's the ratio of the water the sample retains divided by a theoretical max. One could then easily equate that to volume given water has a density of 1g / cc. See I DID remember something from my Jr. high metrics blitz and intro to physical science. 

Well, I don't have time to make samples and do destructive testing so I'm going to eye ball it. My clay / sawdust / millet mix looks to be no more than 25% porous right now. So I have to step it up a notch.

Yesterday I wrapped up the clay slabs so they would not dry anymore while I pondered this little problem. Tonight on the way home I'm going to see about getting some big bags of bird seed at the grocery store. How much though?

Well, the dry mix to wet mix volume went down by about 30% - 40%. So I have about 7 - 8 gallons of clay after it's mixed up. There's about 1.5 - 2 gallons of millet & saw dust in there now. So, I need about another 2 gallons worth of millet. I'll get more and do some additional math on this. 

Jute / Sawdust / Sisal / Hemp / Fiberglass?

Two concerns. One is cracking as it dries. The second is max durability during service. I think I'm screwed on the second one. It is what it is. I coud put in glass fibers, but they will just melt. But ... if I get some kind of organic fiber introduced into the wet mix, I can help the cracking while it dries. I think I can get stuff like this at the craft store. I've seen it used in plaster casting. The second benefit here might be that it provides pathways for the burn out gases to escape. 

Okay, that's all the rambling for now.