"refractory", or kaowool?

[Jack-O-Lantern]

What up guys!? Long time no post. How are you tuff cookies? I've missed ya. Aside from playing in the strange corners of the inet; I've learned alot about smithing since my last visit. But not enough! So here goes:

Does refractory (or mud, clay, plaster of paris with sand, etc. etc.) insulate heat as well as kaowool? 

I ask because I want to make a wood burning forge similar to the whitlox model. They use kaowool and it keeps the heat in well enough for people to report good forging temps. As we all know clay is free, and kaowool is not. So will something like the wash tub forge hold heat in enough for raw wood fuel to get hot enough? Or should I spring for kaowool? I am going to order the whitlox mini forge hood. So it will help either way, but I wanna know what's better. 

Thanks guys and gals

[Frosty]

No point in an insulating refractory in a wood fired forge and Kaowool wouldn't survive the physical abuse. NO plaster of Paris at all, it's for making the walls in your house pretty not containing a fire. 

Insulation has nothing to do with forging temps in a solid fuel forge, any claims it does are marketing hype. The top of the fire is open to the air how in the world does the fire pot hold heat?

Use fire bricks, what little extra it costs will more than make up for it in time over making your own. Seriously, it's a V shaped trench frame with a hard refractory liner. You don't even need a welder: hack saw, hand drill and bits, nuts and bolts and a tape measure. It's almost as simple as a box of dirt forge. Simple is good.

Frosty The Lucky.

[Jack-O-Lantern]

I'm talking about radiant heat on the sides of the forge.

The kaowool route will be like the whitlox: 11 gauge v, kaowool, firebrick.

The washtub route is: refractory, firebrick. Maybe a bucket sized lump of refractory cast as a v, lined with the brick.

Won't the refractory absorb more heat than the thin kaowool?I've never worked with raw wood and my milk moneys on the line! I gotta ask Frosty! 

[Glenn]

3 hours ago, Jack-O-Lantern said:

They use kaowool and it keeps the heat in well enough for people to report good forging temps. As we all know clay is free, and kaowool is not. 

They use fire brick to contain the fire, and koawool to separate the fire brick from the metal frame of the forge. 

Ash, air gap, insulation, and other materials can insulate and slow down the transfer of heat. You will have to play with just how much material is needed to get the results you want. The 55 Forge is thin metal and with an inch or two of ash in the bottom, you can get forging temps and the metal pan is still relatively cool. I used the 55 Forge at a demo supported by 5 gallon plastic pickle buckets full of coal. The plastic showed no sign of melting or damage after the demo. The term relatively cool is subjective and a temp gun will tell the actual story.

With an open forge you are NOT keeping the heat in. You are protecting the frame of the forge from getting overly hot with extended use.

Insulation does work, some insulation is better than others. Mass works also, it takes a lot more of it because it does not insulate as well. 

[Jack-O-Lantern]

Cool Glenn. I was basically wondering if the refractory would have a sponge effect. As opposed to thin kaowool under fire brick giving the heat no where to soak in. I know open forges don't keep heat in, but I want as little absorbtion via the sides as possible.  Raw wood is my best option for fuel so I want it done right. Plus the $ factor makes me wanna do it once. I can't afford to go back to the drawing board.

[ThomasPowers]

PLEASE: Kaowool is a type of refractory so you keep saying will refractory work as well as refractory?  (on the other hand mud and plaster of paris are Not refractories, clay may or may not be a refractory---I once boiled a terra cotta pot in my forge trying to use it as a muffle)

Solid fuel forges often do not have refractory sides as they "overload" the heat output---an extra shovel of coal, coke or charcoal has a lot of BTUs in it. Gas forges use refractories because they generally are trying to use the least amount of fuel possible to get the needed output. (If you were to buy a ton of coal at a good commercial price how many days would it take you forging to use it all?  How much propane would you use in the same time and the cost of it as a comparison? )

[JHCC]

To annotate ThomasPowers's comment, "refractory" (as a noun*) means "a substance that resists being changed by heat". "Insulation", on the other hand, is something that prevents the transmission of energy (in our context, heat). Thus, a particular material may be a refractory (in which case, it will need to be insulated) OR insulation (in which case, it will need to be protected by a refractory OR both (in which case, you are -- broadly speaking -- golden).

 

* As an adjective, it means "stubborn, unmanageable" (as in "refractory children") or "resistant to a process or stimulus" (often medical, as in "a refractory infection").

[Glenn]

There is NO perfect forge, and certainly NO perfect forge for all projects.

If you change the mindset from perfect, to work in progress, you can try many different forge configurations and some will work better for YOU in YOUR location with the projects YOU make.

The 55 Forge was developed so anyone in any third world country could have a working forge at little or no cost. A 24 inch diameter pan forge is NOT small, but a container that can be internally modified in many ways to get the job done. Build one, add fire and be happy. If you want a different type of heat, say long instead of round, then add some brick and mud and change or create a different type fire pot. The 55 Forge is just a container that is easy to change or modify. 

The forge is just a holder for the fuel to make life easier. The BTUs are what we use to heat metal. The metal does not care how it gets hot. We just know the metal moves easier under the hammer when heated. So we heat the metal. 

To address your question, make something, then modify what you made to work better. Change only one thing at a time so you can actually see what difference that one change has made. You will gain experience in forge design (shape) and will find that one shape will do better for one project, and another shape will do better at a different project. 

The idea is to heat metal and have fun forging. Then share your results. 

 

[Frank Turley]

25 minutes ago, JHCC said:

To annotate ThomasPowers's comment, "refractory" (as a noun*) means "a substance that resists being changed by heat". "Insulation", on the other hand, is something that prevents the transmission of energy (in our context, heat). Thus, a particular material may be a refractory (in which case, it will need to be insulated) OR insulation (in which case, it will need to be protected by a refractory OR both (in which case, you are -- broadly speaking -- golden).

 

* As an adjective, it means "stubborn, unmanageable" (as in "refractory children") or "resistant to a process or stimulus" (often medical, as in "a refractory infection").      

And perhaps a related word: fractious.

When I was horseshoeing many moons ago, we would work occasionally on fractious horses.

[ThomasPowers]

My mother very nicely bought me a cane/walking stick when I had a broken toe; but insisted on walking her around the craft fair.  So I am prepared to deal with any of you fractious son of a smiths!

[JHCC]

1 hour ago, Frank Turley said:

And perhaps a related word: fractious.

When I was horseshoeing many moons ago, we would work occasionally on fractious horses.

The OED has "refractory" deriving from refractārius (obstinate, stubborn) and "fractious" deriving from an older sense of "fraction" as "breach of the peace" or "brawling", from Latin frangĕre (to break).

[Jack-O-Lantern]

Alright homies. Apologies for the generalizations. Lemme rephrase my question.

Which kind of forge will heat raw wood fuel more efficiently based solely on it's material components? 

A washtub forge, or a Whitlox forge? Or is the heating economical efficiency the same by virtue of the v shape of both types? As well as the same air input method via a verticle pipe with holes.

I'm choosing one or the other, and if a washtub forge handles raw wood fuel as well as a whitlox does; Then I'm making a washtub forge.

Why pay 150$ (to whitlox) for something that works just as well as something (a washtub forge) that will cost considerably less?

[JHCC]

Let's be clear: you're not actually burning raw wood; you're burning charcoal. A Whitlox-type forge is just turning wood into charcoal before it settles down to the level at which it heats your workpiece. Any V-shaped forge should do pretty much the same thing, given sufficient volume for the as-yet-uncarbonized wood. 

Basically, you've got three options:

1. A V-shaped forge that carbonizes the wood and heats the metal in one apparatus.

2. A charcoal-burning forge (of whatever type) charged with burning coals from a separate wood fire.

3. A charcoal-burning forge to which you add charcoal produced separately in a retort or the like. 

Now, my understanding of the original Tim Lively washtub forge is that it was designed to operate as either 1 or 2; that is, it uses pre-carbonized charcoal. If you want something that behaves like a Whitlox, I suspect that you'll need to make a bigger one than standard.

[ThomasPowers]

As an old moderator on the original neotribal site.  The washtub will work fine just deepen the sides---may want to try a U instead of a V to get the "hang time" to burn the wood to coals before getting to the forging zone.  Note forges like the whitty one tend to be oxidizing and so not the best for blade forging where a reducing fire---product of having a deep bed of coals is wanted.  I've always considered the whitty ones to be sub optimal in my opinion.  Of course I often use charcoal forges for historical demos and usually build them on site using old adobe material and for small stuff more U then V

I much prefer to pre-make charcoal---I sift it from our wood stove ashes, mine it from bonfires or make it just in time with a raised firepit as the charcoal forge is MUCH nicer to use than a wood to charcoal forge!

[Frank Turley]

Was Tao Goo the first neo tribal guy?

[ThomasPowers]

No, just the "loudest"  He claimed to be first but I had used a adobe forge burning charcoal a decade before he had and I never considered that I was "first"... Since blacksmithing has such a long and diverse history it's hard to be "first"---better to be *best*!

BTW I was Bog Iron over there---so long ago I didn't even post under my own name!