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 LibraryAlberta 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 1000F Roasted | 60.00 |
| Alberta Slip | 40.00 |
| 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.
This glaze is most often prepared using the traditional method of simply adding water until the desired consistency is achieved (do the initial mix with 8 parts water and 10 powder). No flocculant additions are generally needed and application properties are very good as long as the slurry is not too viscous or too runny (dries quickly without cracking and, after dipping, there is minimal dripping). A weight ratio of 90 of our tap water and 100 powder produces 1.435 specific gravity. A 1-2 second dip in 1850F bisque-ware produces the right thickness and there is minimal dripping, even coverage and quick drying. Be careful that it does not go on too thick or cracks on drying, if needed dip quicker, add a little more water or bisque higher. Alberta Slip does not respond to Epsom salts as typical glazes for creating a thixotropic slurry, but that is not a problem since this recipe works well as is.
3000 grams of powder mix makes about 1 Canadian gallon.
Roasting Alberta and Ravenscrag Slips at 1000F: Essential for good glazes
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about 1 kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying (if used raw the GA6-B and similar recipes will crack as they dry and then crawl during firing). Roasting eliminates that. Calcining to 1850F sinters some particles together (creating a gritty material) while roasting to 1000F produces a smooth, fluffy powder. Technically, Alberta Slip losses 3% of its weight on roasting so I should use 3% less than a recipe calls for. But I often just swap them gram-for-gram.
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%.
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 buff stoneware (left) and iron stoneware (right) fired to cone 10R. The glaze is made using a blend of roast and raw (as instructed at the PlainsmanClays.com product page). Alberta Slip was originally formulated during the 1980s (using Insight software) as a chemical duplicate of Albany Slip. The inside: G2947U transparent. The intensity of the color depends on firing, add a little iron oxide (e.g. 1%) if needed.
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.
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).
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 use as a liner glaze).
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.
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 Slip | 50.00 |
| Alberta Slip 1000F Roasted | 50.00 |
| Add | |
| Mason 6666 or 6600 | 1.00 |
| 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 roasted 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.
Roasting Alberta and Ravenscrag Slips at 1000F: Essential for good glazes
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about 1 kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying (if used raw the GA6-B and similar recipes will crack as they dry and then crawl during firing). Roasting eliminates that. Calcining to 1850F sinters some particles together (creating a gritty material) while roasting to 1000F produces a smooth, fluffy powder. Technically, Alberta Slip losses 3% of its weight on roasting so I should use 3% less than a recipe calls for. But I often just swap them gram-for-gram.
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 1000F Roasted | 50.00 |
| Alberta Slip | 50.00 |
| Add | |
| Red Iron Oxide | 3.00 |
| 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).
Roasting Alberta and Ravenscrag Slips at 1000F: Essential for good glazes
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about 1 kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying (if used raw the GA6-B and similar recipes will crack as they dry and then crawl during firing). Roasting eliminates that. Calcining to 1850F sinters some particles together (creating a gritty material) while roasting to 1000F produces a smooth, fluffy powder. Technically, Alberta Slip losses 3% of its weight on roasting so I should use 3% less than a recipe calls for. But I often just swap them gram-for-gram.
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 1000F Roasted | 50.00 |
| Alberta Slip | 50.00 |
| Add | |
| Calcium Carbonate | 5.00 |
| Red Iron Oxide | 2.00 |
| 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.
You 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.
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 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).
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).
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.
Roasting Alberta and Ravenscrag Slips at 1000F: Essential for good glazes
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about 1 kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying (if used raw the GA6-B and similar recipes will crack as they dry and then crawl during firing). Roasting eliminates that. Calcining to 1850F sinters some particles together (creating a gritty material) while roasting to 1000F produces a smooth, fluffy powder. Technically, Alberta Slip losses 3% of its weight on roasting so I should use 3% less than a recipe calls for. But I often just swap them gram-for-gram.
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).
Alberta Slip:Ravenscrag Cone 10R Celadon
Code: GR10-E
A celadon recipe affording slurry and fired properties control (because proportions of raw and calcined materials and frit can be adjusted)
| Alberta Slip 1000F Roast | 47.50 |
| Ravenscrag Slip | 47.50 |
| Ferro Frit 3134 | 5.00 |
| 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. Fine tune the thermal expansion by changing the frit (e.g. frit 3134 for higher expansion, 3249 for lower, 3124 for nuetral).
Since this glaze is 90% clay, roast half of the Alberta Slip complement to reduce the drying shrinkage (for application to bisque ware). If applied to leather-hard ware it should be OK as to use raw Alberta and Ravencrag Slips.
GR10-E Ravenscrag:Alberta Slip with 10% calcium carbonate
At cone 10R this produces an overly melted glaze. It also crazes.
Ravenscrag GR10-E celadon glaze
(50:50 Ravenscrag Slip:Alberta Slip) at cone 10R on porcelain (right) and stoneware (left).
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 Alberta Slip Celadon mug by Tony Hansen
The outside glaze on this cone 10R mug (made of Plainsman H550) is G2881B, simply an Alberta Slip:Ravenscrag Slip 50:50 mix (the Ravenscrag Slip portion was roasted). 5% Ferro Frit 3134 was added to get a little better melting (to produce a high gloss). This produces a good celadon with great working and application properties. Inside glaze: Pure Ravenscrag Slip (mixed 50:50 roast and raw).
Roasting Alberta and Ravenscrag Slips at 1000F: Essential for good glazes
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about 1 kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying (if used raw the GA6-B and similar recipes will crack as they dry and then crawl during firing). Roasting eliminates that. Calcining to 1850F sinters some particles together (creating a gritty material) while roasting to 1000F produces a smooth, fluffy powder. Technically, Alberta Slip losses 3% of its weight on roasting so I should use 3% less than a recipe calls for. But I often just swap them gram-for-gram.