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Cone 10R Glaze Recipes

Ravenscrag by itself fires to an excellent cone 10 glaze, especially as a silky matte base.

For functional glaze, consider testing for leaching, crazing and cutlery marking.

Courtesy of Digitalfire Reference Library

Alberta Slip Base Cone 10R

Code: GA10-A

Alberta Slip at 60:40 calcine:raw makes a great tenmoku-like glaze at cone 10R

Alberta Slip Calcined60.00
Alberta Slip40.00
100.00

Alberta Slip, like the original Albany Slip, melts to a beautiful glossy deep brown at cone 10R. Use as a pure glaze, it stops just short of being Tenmoku at cone 10R (a 1% iron addition is needed). Unlike many Tenmokus, it is not too fluid.

The color of this glaze varies considerably with thickness. Its thermal expansion is low enough that it does not easily craze on stonewares or porcelains.

Like Albany, Alberta Slip is a clay. It shrinks during drying, more than Albany did. Using pure Albany as a glaze required calcining part of the mix (to prevent cracking during drying). Alberta Slip is the same, however it requires a higher calcine-to-raw proportion. While calcining is an extra step, the capacity to change the calcine:raw proportion gives you control over the properties of the slurry. Ideally it needs to be plastic enough to suspend well and harden on the ware, but not so plastic that it shrinks too much during drying. For calcining instructions please visit http://albertalslip.com.

In our lab we can make 1 Canadian gallon using a mix of 2800 water and 3000 dry (1500 Alberta Slip, 1500 Calcined Alberta Slip). This produces a specific gravity of 1.43 at about the right viscosity for dipping. We add a 1-2 grams of Epsom Salts to this to gel the slurry a little for better application properties. A 1-2 second dip in 1850F bisque ware produces the right thickness.

Pure Alberta Slip at different thicknesses in reduction

A 13 inch vase glazed with 100% Alberta Slip fired at cone 10R. The glaze was sprayed on. It is about 60% calcine and 40% raw powder. When it is very thin, as on the shoulder, it is quite metallic and varies from deep red to brown (depending on thickness). Where thick it is a tenmoku high gloss. The spots on the shoulder are thicker areas that have glossed.

Alberta Slip as-a-glaze at cone 10R

This is 100% Alberta Slip (outside) on a white stoneware clay fired to cone 10R. The glaze is made using a blend of 60% calcine and 40% raw (as instructed at the albertaslip.com support website). Alberta Slip was originally formulated during the 1980s (using Insight software) as a chemical duplicate of Albany Slip. The inside: A Ravenscrag Slip based silky matte.

Decal firing to 1500F has darkened 10R Alberta Slip glaze

These mugs are the same clay and glazed with a 50:50 raw:calcine Alberta Slip mix (GA10-A) and fired to cone 10R. Both looked like the one on the left. The one on the right has a decal on the inside, it was fired to 1500F. This firing has made the glaze significantly glossier, darker, deeper and more vibrant. Why? I have no idea. I have 20 more using this glaze and made from this and other clays, they all did the same thing.

Laguna B-Mix Cone 10R mugs with Alberta and Ravenscrag glazes

B-Mix is a popular high-ball clay very plastic grey cone 10R stoneware in North America. The two mugs on the left have pure Ravenscrag Slip on the inside (the middle on the outside also), it fires almost transparent with a slightly silky surface. Pure Alberta Slip is employed on the outside of the left one and the inside of the right one. The outside of the right one is RavenTalc silky matte. In all cases the Ravenscrag and Alberta Slip are mixed half-and-half calcined and raw. B-Mix fires dark enough and with enough specks that a normal transparent glaze is not very interesting. But these Ravenscrag ones look much better (for liner glazes).

B-Mix with Ravenscrag Slip inside and Alberta Slip outside

Fired cone 10R. The one on the right contains 10% of Plainsman A1:St Rose Red mix to add speckle.

Compare Ravenscrag and Alberta Slip tenmokus at cone 10R

GR10-K1 Ravenscrag tenmoku (left) compared to Alberta Slip tenmoku GA10-B (center) and pure Alberta Slip (right).

Calcining Alberta Slip

Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.

Pure Alberta Slip cone 10R with increasing amounts of iron

The far left has 1% iron oxide, the far right 7%. Crystallization of the iron begins around 3%.

 


Alberta Slip Black Cone 10R

Code: GA10-D

You can make a black glaze at cone 10R using only 1% black stain in a 100% calcine:raw mix of Alberta Slip

Alberta Slip50.00
Alberta Slip Calcined50.00
Add
Mason 6666 or 66001.00
101.00

Alberta Slip is a great base for black glazes at cone 10 reduction, only 1% black stain is needed to obtain a jet black glossy. Increasing amounts of stain up to 5% move toward a matte black for Mason 6600 (they remain glossy for Mason 6666). Adding 5-10% black stain and 5-7% iron produces a crystalizing intense gunmetal black. Mixtured additions of Mason 6600:6666 (e.g. 1:1, 2:2) produce metallic surfaces.

Like other high-percentage Alberta Slip glazes, you must use a mix of calcined a raw powder. See the preparation page at http://albertaslip.com for more information.

Alberta Slip as a base for glossy black glazes at cone 10R

A jet a black glossy glaze for cone 10R is as easy as 1% black stain and 99% Alberta Slip (Mason 6666 or 6600). Of course, the 99% is a mix of calcine and raw material (starting at 50:50).

A metallic, silky crystal black glaze based on Alberta Slip

This is a 50:50 mix of calcine and raw Alberta Slip plus 5 parts Mason 6600 black stain, 5 Mason 6666 black and 7 iron.

Cone 10R Gunmetal black glaze made using Alberta Slip

A 50:50 mix of raw and calcined Alberta Slip with 5% Mason 6666 stain added. The slurry was ball milled. Fired at cone 10R.

Additions of black stain to Alberta Slip at cone 10R

Alberta Slip (50:50 calcine:raw mix) with 1, 2, 3, 4 and 5% added Mason 6666 black stain. Fired at cone 10R. Semi-gloss blacks are produced. Increasing stain percentage above about 3% does not darken the color appreciably.

Calcining Alberta Slip

Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.

 


Alberta Slip Iron Crystal Cone 10R

Code: L3341B

By adding a little iron to 100% Alberta Slip you can make an iron crystal glaze.

Alberta Slip Calcined50.00
Alberta Slip50.00
Add
Red Iron Oxide3.00
103.00

Typically this type of glaze is made by adding up to 15% iron oxide to a transparent glaze. However using Alberta Slip, you only need 3% iron (this is an advantage because 10% iron flocculates the glaze, requiring the addition of more water which in turn causes crawling). Adjust the iron to get the amount of crystal development and metallic appearance desired. In reduction the extra iron will flux it more so melting should be good.

Alberta Slip with 3% iron oxide added. It crystallizes.

This is fired in cone 10R. The effect becomes more intense by 5%. To achieve this same effect using Ravenscrag, which has much less natural iron content, 10% added iron is needed (which is, of course, much messier to work with).

Calcining Alberta Slip

Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.

 


Alberta Slip Tenmoku Cone 10R

Code: GA10-B

You can make a tenmoku from Alberta Slip by adding only 2% iron oxide and 5% calcium carbonate

Alberta Slip Calcined50.00
Alberta Slip50.00
Add
Calcium Carbonate5.00
Iron Oxide2.00
107.00

Tenmoku glazes normally contain 10%+ iron oxide, they are extremely messy to use and often have poor slurry suspension properties and are difficult to apply evenly. This recipe is totally different, it is so much cleaner to use. It applies very evenly and suspends well.

Uou can adjust the drying hardness, drying shrinkage and suspension properties by adjusting the proportion of calcined to raw Alberta Slip (see the preparation page at http://albertaslip.com for more information). You can change the degree of melting by adjusting the calcium carbonate and the intensity of color by tuning the iron oxide.

Alberta slip vs Alberta Slip tenmoku

Alberta Slip 100% (left) and Alberta Slip Tenmoku (right). The tenmoku is a little more opaque and forms the characteristic brown crystals on edges of contours (e.g. rim).

Calcining Alberta Slip

Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.

Tenmokus made from Alberta Slip and Ravenscrag Slip

GR10-K1 Cone 10R Ravenscrag Tenmoku (right) compared to Tenmoku made from Alberta Slip (left, it is 91% Alberta Slip with 5% added calcium carbonate and 2% iron oxide). Left is Plainsman P700 porcelain, right is H570. Tenmokus are popular for the way they break to a crystalline light brown on the edges of contours.

Which tenmoku base is better: Alberta Slip or a clear glaze?

Right: Alberta slip is almost a Tenmoku glaze by itself at cone 10 reduction. To go all the way only 1-2% more iron is needed (plus a little extra flux for melt fluidity, perhaps 5% calcium carbonate). Compare that to crow-baring a clear glaze into a tenmoku (left): This is G1947U plus 11% red iron oxide. That produces a slurry that is miserable to work with (it stains everything it comes into contact with) and turns into a jelly on standing.

Ravenscrag Tenmoku vs. Alberta Slip Tenmoku

All of these are on a cone 10 reduction fired iron stoneware (Plainsman H443). Far left: G2894 Ravenscrag Tenmoku with 10% whiting and 10% iron oxide added. Center: Pure Alberta Slip plus 5% whiting and 1% iron oxide. Right: Pure Alberta Slip plus 5% whiting and and 2% iron. The Alberta Slip versions are less messy to use because so much less iron is needed (iron also causes the slurry to gel). The Ravenscrag version is running, it is too fluid. Likely 5% calcium carbonate would be enough (and maybe less iron).

Ravenscrag Tenmoku vs. Alberta Slip Tenmoku on porcelain

Body is Plainsman P580. Far left: G2894 Ravenscrag Tenmoku with 10% whiting and 10% iron oxide added. Center: Pure Alberta Slip plus 5% whiting and 1% iron oxide. Right: Pure Alberta Slip plus 5% whiting and and 2% iron. The Alberta Slip versions are less messy to use because so much less iron is needed (iron also causes the slurry to gel). The Ravenscrag and higher iron Alberta Slip versions are running, they are too fluid. The rust colored crystals are not developing the way they did with these glazes on an iron stoneware (in the same firing).

 


Alberta Slip:Ravenscrag Cone 10R Celadon

Code: GR10-E

A celadon recipe containing only two ingredients. It affords slurry and drying control because proportions of raw and calcined materials can be varied.

Alberta Slip47.50
Ravenscrag Slip47.50
Ferro Frit 31345.00
100.00

This is a celadon that you can tune to your needs. It works well on dark and light stonewares and porcelains. Adjust the proportions of Alberta Slip to Ravenscrag Slip to fine tune the color (more Ravenscrag for lighter color). Adjust the amount of frit to tune the amount of gloss and melt fluidity. Calcium carbonate also works, but may produce more bubbles floating in the matrix. If you fire to cone 11, then no flux may be needed.

You can fine tune the thermal expansion (e.g. frit 3134 for higher expansion, 3249 for lower, 3124 for nuetral).

Since this glaze is 90% clay, you will need to calcine half of the Alberta Slip complement to reduce the drying shrinkage if it will be applied to dry or bisque ware (if applied to leather hard ware it could be OK as is).

Ravenscrag Celadon and silky matte glazed mug by Tony Hansen

The outside glaze on this cone 10R mug (made of Plainsman H550) is simply an Alberta Slip:Ravenscrag Slip 50:50 mix with 5% added Ferro Frit 3134 (the Alberta Slip is calcined). This produces a stunning celadon with great working and application properties. Inside glaze: Ravenscrag Slip 90%, talc 10% (a matte having an extra ordinary silky texture). Learn more at ravenscrag.com.

Calcining Alberta Slip

Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.

GR10-E 50:50 Alberta Slip:Ravenscrag Slip celadon at cone 10R

On a white stoneware and a porcelain. The glaze is transparent, it has depth and varies in shade according to thickness, breaking to a much lighter shade on the edges of contours.

Ravenscrag GR10-E celadon glaze

(50:50 Ravenscrag Slip:Alberta Slip) at cone 10R on porcelain (right) and stoneware (left).

GR10-E Ravenscrag:Alberta Slip with 10% calcium carbonate

At cone 10R this produces an overly melted glaze. It also crazes.

 

Courtesy of Digitalfire Reference Library

Alberta Slip Base for cone 10 oxidation

Code: GA10x-A

Alberta Slip creates a glossy transparent brown at cone 10 with the simple addition of 10% frit.

Alberta Slip Calcined45.00
Alberta Slip45.00
Frit 313410.00
100.00

In oxidation, Alberta Slip creates a glaze that is more transparent and lighter in color. It also melts less than in cone 10R so a little flux is needed (thus the use of the frit here). Since Alberta Slip is plastic, you need to use a mix of calcined and raw powder (see http://albertaslip.com for information on preparation of the calcine).

Alberta Slip plus 10% frit 3134 fire at cone 10 oxidation.

Calcining Alberta Slip

Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.

 

Alberta Slip is a product of Plainsman Clays and is mined in North America's premier "Clay Country" (near Ravenscrag, Saskatchewan, Canada and also in Montana, USA)