Raku
28 glazes / Spectrum
Twenty eight raku glazes from Spectrum's 800 series, and the widest raku palette on our shelf.
Twenty six are in circulation. Amethyst and Orchid Pink are discontinued and stay here as a record rather than as an option.
Spectrum are direct about what these do: metallic flashes, smoky crackle, and results that cannot be duplicated. Every firing is its own experiment.
Cone 06Bisque to Cone 0410 studio favorites
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Raku by the numbers
28glazes on our shelves
18good on texture
10studio favorites
13carry an up-charge
2discontinued by the maker
Friendly studio tip for this glaze family
You cannot use this shelf on your own. Raku runs as a workshop, at night, with tongs and gloves and somebody calling the moves, and attending one is what unlocks it. That is why these bottles carry a flame instead of a membership color.
Ask a staff member when the next one is, and watch your email.
How the Raku line works
Spectrum fire this series anywhere from 1600F up to cone 06, which is 1850F, then cool to about 1600F before the pot comes out red hot and goes into the can.
What the can is packed with changes the result more than anything you brush. Spectrum give the clearest example anyone publishes: the same glaze reduced in newspaper can come out a beautiful blue, and reduced in sawdust can come out metallic copper.
Coats
Spectrum set these up for brushing and say they can be poured or dipped if thinned a little with water.
Peak temperature matters here. Spectrum recommend most of the series to a peak around 1700 to 1750F and a subset around 1600 to 1650F, and note that different combinations of peak and reduction temperature give different results.
Layering
The reduction does more than layering ever will. What the can is packed with, how fast the lid goes on and how long it stays shut change the surface more than a second coat would.
Food and safety
Raku is not food safe and never will be. Not with a sealer, not with a liner glaze.
The body is fired hundreds of degrees below vitrification so it stays porous, the glaze is crazed, and raku glazes carry copper and other metals. It is not watertight either: water passes through the body over hours, so a raku vase full of flowers is a slow leak on your furniture.
Spectrum add that although none of these contain lead, many are over the copper threshold and are considered toxic in the liquid state. That is a handling concern in the glaze room, which is another reason this shelf is workshop only.
Clays that suit Raku
Raku clay is not optional. The pot goes from around 2000 degrees to open air in about four seconds.
Use one of these threeB-Mix with Grog, 52 Buff, or Berlin Gray. Those are the bodies we raku on. A piece on anything else does not go in the firing.
Why grog mattersThe coarse particles give the thermal shock somewhere to go. A smooth, tight body has no give and cracks on the way out of the kiln.
Build for itSoften interior corners, reinforce seams with a blended coil, compress the floor. Narrow necks and sealed forms trap steam and are the ones that burst.
Decide earlyThis is the one firing where the making decisions happen weeks before the glazing does.
From The Clay Hole University
More info about Raku below, but first... Everything we teach about glazing, written down and taught properly. These are the glaze lessons, and they are a small corner of a library that runs from centering your first pot to selling your work.
GuideGlaze Brushing Techniques, Coat by Coat
GuideGlazing Big and Intricate Pottery Faster
GuideGetting the Most Out of the Mega Glaze Tool
GuideMaking, Logging and Dialing in Test Tiles
GuideGlaze Problems, Causes and Fixes
GuideGlazing on the Wheel for Even Coats and Clean Bands
GuideOxide and Carbonate Washes
GuideWhen to Use Celadon Glazes
GuideHow to Use Dipping Glazes
UnderglazeHow to Use Underglaze: Techniques, Rules and Firing
UnderglazeMishima: How to Inlay Slip and Underglaze into Carved Lines
UnderglazeWipe-Away Texture: Underglaze and Oxide Washes on Bisque
The Raku test tile pot
This family does not have a test tile pot. The colors and results come out close enough to what the book shows that a pot would not tell you much more, so work from the printed Glaze Bible and the tile above.
About these images and what your pot will actually look like
We have done our best to represent every glaze here accurately, and you should still expect your pot to look different from what is on this screen.
Our glaze tile images are digitally created. They are built to show the character of a glaze, not to be a color match.
A screen is not a printout, a printout is not a test tile, and a test tile is not a finished pot. Each step in that chain shifts what a glaze looks like, sometimes a lot.
On top of that, the pottery itself changes the result: the clay body, how thick the glaze went on, whether it was brushed, dipped or sprayed, what was layered under or over it, where the piece sat in the kiln, how hot that spot ran, how fast it cooled, what was fired next to it, and how much texture the surface had. Two pots glazed from the same jar on the same day can come out different.
Treat every image here as a starting point, and treat a test tile fired on your own clay as the real answer.