Proportions of clay, sand and ash to line a Lively washtub forge?

[Billinthedesert]

Anyone recall the ratio of these materials to build the lining in a Tim Lively washtub forge? I've built a couple but is has been years, and I no longer have my VHS or DVD copies of "Knifemaking Unplugged." I have wood ash, Lincoln fire clay and play sand on hand.

 

[Alan]

A good starting point is roughly equal sand and clay with a smaller portion of ash mixed in. The key is adjustability, aim for a packable mix that dries without cracking and holds shape after firing,

 

[Billinthedesert]

Alan, thanks. I got this right the first time in Oregon, but had major cracking the second time here in New Mexico.