clay linning

[Warrigal]

By trolling the web I got the suggestion of lining the bottom of my "forge" with ash and dirt ( ash from my wood fired heater) Forge is in inverted comma's because it started life as a comercial charcoal fired BBQ
I plan ( tomorrow if the stars are in alignment or whatever it is that delivers other jobs for me to do) to "strain" all the charcoal out of the Firebed and then cover this insulating layer with a layer of clay I got from my sister who works in an Art supply shop. As it turns out mum and dad have just dug up their back yard and removed a lot of clay, that will be finding it's way over to my place somewhere in the next week.
Outta interest my cast iron fire, closed in like a modern combustion stove but externally all cast iron. Has burn only wood cast into the front wall. Pity lotsa coal around here.
Carl

[kenG]

I getting the impression the linning material isn't has important as just having a buffer material. Thanks for all the responses.
Ken

[hill.josh]

Originally Posted by kenG

Josh,
When you say Portland Cement, I assume you are talking about type I Quikrete like Ace sells? and just plain ol' sandbox sand mixed together? That's simple enough.
Thanks,
Ken

Ken, its type I/II quickrete so I think its the same. Just as long as its portland cement and plain sandbox sand is what I use..
good luck forging man

[civilwarblacksmith]

One question would be, How thick are the walls and floor of your forge. If the are 1/4 thick or thicker and you are not a professional full time smith that will be operating the forge 8-10 hrs a day everyday, you really don't need to line the forge with anything.

I have 2 forges that are at the least 1/4'' and have no lining material. One is used about everyweekend for re-enactments.

I just picked up a used forge and fixed it up for use on the following weekend. When bought, this forge had a refractory material in it. I believe it was cement. The sides are 14 - 12 guage and after breaking the material off the bottom I found it to be about 14 guage (heavy 1/16") metal. That was why they lined it. I have since replaced the bottom with 1/4" plate and do not need lining.

[azIRonSmith]

Definitely clay the pot. It's a lot cheaper to replace clay than it is to repair/replace the pot.

I would stay away from cement. It tends to spall at high heat (i.e. explode).

A better clay would be a cone 10 (ceramics term for high fired) clay from a ceramics supply store.

You can get 25lbs bags for about $6-$10. I add some very dry sand and I also use vermiculite as a filler similar to the sawdust that philip suggested. Since this clay is meant to be fired at over 2000 degrees, it will stand up to the heat of your forge.

Ground clay may contain anything and everything and you have no guarantee as to the heat rating. It may literally melt in your forge.

You will want to let the clay air dry for quite a few days depending on your weather. Dry and hot = less days. Cold and wet = more days. This is to let the clay mix dry out slowly to keep it from cracking. Keep some extra clay mix in an air tight container to repair any cracks.

Once you are ready to fire it up, do a small fire or even wood fire to allow the rest of the moisture to slowly dry out the rest of the moisture. This will help keep the clay from cracking a lot on the first fire.

There is being frugal and then there is being down right crazy dangerous cheap. ;-P