Bracker Portable Raku Kiln

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Complete Raku Kiln Kit
Includes:

	Kiln
	Burner
	Case of Soft Firebrick
	16" Kiln Shelf
	Raku Tongs (Kemper RK45)
	Leather Gloves
	5# Crackle White Raku Glaze (DRY)
	All Shipping Costs! (Continental USA only)

$565

This is a great, inexpensive way to have your own Raku kiln. You can buy the complete kiln including shipping for only $565.

Biography: The Designer - Bill Bracker

William (Bill) Bracker (B.F.A. and M.F.A. - University of Nebraska at Lincoln) was a professor of Ceramic Design at Texas Lutheran College, Purdue University, and the University of Kansas. While at Purdue University, he designed a portable Raku Kiln using ceramic fiber (an innovative new product at that time). He was the first to use ceramic fiber in Raku kilns and demonstrated his kilns at an N.C.E.C.A. conference in the 1970's. Continued demonstrations occurred in locations from Colorado to Virginia. Over many years of testing and personal use, he further refined his initial designs. The Bracker Raku Kiln has been constructed for over 30 years in strict accordance to Bill's design specifications. We feel that this kiln continues to be the most portable and cost-effective on the market.

Description

It is a lightweight and portable design for firing ceramic pieces in your own backyard.

The kiln is made by lining a cage of wire fence material and a metal garbage can lid with one half inch thick fiber blanket. The fiber is then rigidized with a mixture of sodium silicate and water. The use of the fiber allows the ceramicist to have the insulating qualities of soft insulating firebrick, yet is light enough that anyone is able to pick it up.

For the base of the kiln, you get a case of firebricks.
(Please do not fire directly on concrete or the concrete will crack.)

Kit Specifications:

	Interior dimensions 18" x 24"
	Propane Burner (torch) .5 Million BTU's/hour Red Dragon, includes shutoff valve, hose, and attachment to the propane tank.
	Firebrick for pad rated to 2600 degrees Fahrenheit
	Burner entry point and exit holes (peep holes) confirm to Fredrick Olsen's standardization configurations
	Lightweight and portable design utilizing garbage can lid with top handle allows for multiple Raku set-ups with only Kiln necessary
	Made with 1/2" thick, #6 density ceramic fiber (insulation properties of 3" Firebrick) rigidized with sodium silicate and water
	Fiber construction provides lower BTU loss than Firebrick which ultimately results in better insulation, lower fuel consumption, and faster firings (initial firing in a cold kiln should take less than one hour. Successive firings should take less than 30 minutes).
	Can be relined fairly easily and inexpensively
	NOTE: You CANNOT bisque in this kiln. It fires too fast and cannot be controlled enough.

Set-up and Firing:

	Use firebricks to create the pad for the Kiln (using 10 -15 bricks)
	3 more firebricks are used as post for kiln shelf
	2 more firebrick can act as the prop for the burner (this should leave you with a few extra)
	Place the pot on the kiln shelf
	Fiber Kiln is then lowered over the set-up.

You are now ready to fire!

Firing tips:
To avoid thermal shock on the shelf...

On the first firing of every firing session...

- Heat up the kiln slowly.
- Set the flame low and plan on it taking 60 minutes.

For the additional firings

- Set the flame higher and plan on it taking 30-40 minutes.

To get maximum heat out of the torch...

Keep the edge of the burner about 1/2" or so outside the shell of the kiln. Aim the flame into the kiln. This gives the flame lots of oxygen to burn.

If it is windy outside, set up a wind block to help keep the heat inside of the kiln. Or find a less windy part of the yard to fire in.

Tip: Some people struggle with how to move large pieces without breaking them. With this set-up you can buy an extra set of kiln bricks and have two separate platforms. When your first load is ready, simply move the Fiber Shell and Burner to the next platform, and reduce your pieces in place.

With this kiln, all you need for firing is...

	Hand protection*
	Buy or rent a propane tank (often available at hardware stores). A 100lb tank is recommended so you can get proper gas flow through the burner and maximum heat.**
	Cement blocks to construct the kiln on
	Find at least one metal garbage can with a lid (for doing your reduction)
	Find combustible materials such as torn newspaper, leaves, sawdust or pine needles (for the oxygen reduction process)
	You may also want a metal tub of water and an extra metal can for holding the Raku tongs, which can be very hot after use.

* It is possible to use just the plain leather gloves, as long as you only handle the pots with tongs, and you work quickly. It is recommended that you use some type of high temperature gloves, such as the Kevlar Mitts shown here.

Tips, pointers, troubleshooting

Q: Why does the manufacturer recommend a 100 lb propane tank?
A: To answer, it helps to understand the properties of propane. Propane is gas at room temperature. It is inefficient to sell it that way so it is compressed, bottled and sold as a liquid (LPG) Liquid Propane Gas.

To burn LPG, you must be turned back into vapor. That can be accomplished by releasing the pressure in the bottle by opening the valve, and out comes the propane gas. There are a few complications though.

The rate at which the LPG will turn into propane vapor depends mainly upon two things, 1) the temperature at which the propane is changing state from liquid to vapor and 2) the surface area of the LPG in the bottle.

The warmer the LPG is, the easier it vaporizes. Additionally, the warmer the vapor is as it passes though the valve, the less likely the valve will freeze up. (As gas changes from high to low pressure, it requires heat, so much so that it can actually freeze up the valve.)

Also, the liquid can only turn to vapor at the liquid surface in the bottle. The more surface area, the faster vapor can be created. Bigger tanks, particularly horizontal ones, have more surface area.

So, the reason a 100 lb tank is recommended is because it helps keep the tank warmer for the state change from liquid to vapor. It also provides greater surface area of the LPG for the state change.

(I hope I have describe this accurately. For more info see the "Ideal gas Law" and the "First law of Thermodynamics" in your physics book, or try a Google search. )

Q: I have a big 100 lb propane tank and I'm still have problems getting the kiln hot enough. What's wrong?
A: Here are a few things to try:
- The colder the outside air, the more difficult it is to get sufficient flow of gas for your tank. Cold weather and/or high altitude locations can be problematic.

- Windy locations can also cool tank and the kiln. Try keeping your kiln and tank in an area protected from the wind.

- Check the safety flow switch on the torch. It may have become accidentally set.

- When setting up the kiln, locate the torch about 1" outside the kiln body. otherwise the torch may not breath well and will burn cooler.

$565