Alternate Names: Archie Bray Slip
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This material was formulated as a physical and chemical substitute for the late and very popular Albany Slip from New York state. Like Albany, it is a low melting iron stained clay. Alberta Slip is more consistent than Albany was since it is made from a blend of raw materials.
Alberta slip has a slightly lower iron content than Albany had so some glazes may not fire as dark (this can be counteracted by adding additional iron oxide). Alberta slip melts as well and works in most glazes that call for Albany. Alberta slip is more plastic (less silty) so recipes containing larger proportions may shrink and crack during drying (requiring the use of a calcine:raw mix).
Plainsman Clays has made this material for many years and it is established in the market place across North America. It has its own website at albertaslip.com. You can use Alberta Slip at 100% (raw:calcine mix) to create a chocolate brown glossy glaze at cone 10. Many Albany glazes were based on the addition of an active flux that increased melt fluidity so that greenish and yellowish iron crystals grew on cooling. Many black glazes were based on Albany Slip, since it already contained lots of iron only a little more and some extra cobalt or manganese were needed.
The plasticity of Alberta Slip is very helpful in suspending glaze slurries. However if there is more than about 40% (with no other clays), then you must use a raw:calcine mix. The albertaslip.com website has information on how to do the calcining and how to adjust for the change in LOI.
The analysis of this material was changed here in Sept 2013, not because the material changed, but because they switched to an actual assay instead of a calculated analysis.
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).
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.
These are two runs of Alberta slip (plus 20% frit 3134) in a GLFL test to compare melt flow at cone 6.
This is 85% Alberta Slip, 11% lithium and 4% tin fired at cone 6 in oxidation. Like the original Albany version, it has a very low thermal expansion (because of the high lithium content) and likes to shiver on many bodies.
2, 3, 4, 5% rutile added to an 80:20 mix of Alberta Slip:Frit 3134 at cone 6. This variegating mechanism of rutile is well-known among potters. Rutile can be added to many glazes to variegate existing color and opacification. If more rutile is added the surface turns an ugly yellow in a mass of titanium crystals.
An example of how a glaze that contains too much plastic clay has been applied too thick. It shrinks and cracks during drying and is guaranteed to crawl. This is raw Alberta Slip. To solve this problem you need to tune a mix of raw and calcine material. Enough raw is needed to suspend the slurry and dry it to a hard surface, but enough calcine is needed to keep the shrinkage low enough that this cracking does not happen. The Alberta Slip website has a page about how to do the calcining.
This has produced a defect free fired surface at cone 6 oxidation on a dark and light burning clay body. To get this type of surface for stoneware bodies it is important to soak the kiln at cone 6, then cool it 100 degrees F and soak it again for half an hour. For coarser clays it is also helpful to program a 200 degree per hour cool all the way down to 1500F.
At cone 5R pure Alberta Slip (left) is beginning to melt and flow down the runway of this tester. It is producing a matte gunmetal surface. Pure Ravenscrag Slip (right) is just starting (it needs frit to develop melt fluidity at this temperature). The iron in the Alberta Slip is melting it because of the reduction atmosphere in the kiln (it does not move like this in oxidation).
Compared to a slow-cooled, high-melt-fluidity iron crystal glaze fired at cone 6 oxidation (right).
A nice thing about this is that the percentage of metallic oxide is comparatively low compared to other metallic glazes. And, it is iron oxide, which is not toxic at all.
90% Alberta Slip (which is a mix of half and half raw and calcine) and 10% Ulexite fired at cone 6. A dazzling fluid dark amber transparent. You could also do this using a high-boron frit.
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.
The inside glaze is pure Ravenscrag Slip and the outside glaze is a 50:50 mix of Ravenscrag and Alberta Slips. Each of the glazes employs an appropriate mix of calcined and raw clay to achieve a balance of good slurry properties, hardening and minimal drying shrinkage. Ravenscrag needs less calcined since it is less plastic than Alberta Slip.
This high-Alberta-Slip glaze is shrinking too much on drying. Thus it is going to crawl during firing. This common issue happens because there is too much plastic clay in the glaze recipe (common with slip glazes). Clay is needed to suspend the other particles, but too much causes the excessive shrinkage. The easiest way to fix this is to use a mix of raw and calcined Alberta Slip (explained at albertaslip.com). The calcined Alberta Slip has no plasticity and thus much less shrinkage (but it still has the same chemistry). Many matte glazes have high kaolin contents and recipes will often contain both raw and calcined kaolin for the same reason.
However this version employs Ferro Frit 3195 instead of Frit 3134 to flux the Alberta Slip. Polar Ice is a cone 6 super-white translucent porcelain from Plainsman Clays.
Albany Slip was a pure mined material, Alberta Slip is a recipe of mined materials and refined minerals designed to have the same chemistry, firing behavior and raw physical appearance.
This is 100% of the pure material. Notice how the iron is fluxing it more on the left, it is beginning to run. And how the reduction atmosphere amplifies the color of the iron (by changing it to the metallic state).
This glaze is 85% Alberta Slip, a plastic clay. Understandably it shrinks on drying and cracks (left). Normally part of the clay must be calcined to cut the shrinkage to prevent this. But it is still just for single-layering (if others are dipped or painted over it they would flake it off). The one on the right is the same but with 1% CMC gum added (it also has 2% added brown stain and a little higher specific gravity). This is magic! Not only does it not crack but it is double layered. Very thick strokes of a commercial brushing glaze have been applied and they will not crack either! This is the secret of dipping-glazes for multi-layering. The down side: Much more patience during dipping, they drip a lot and take much longer to dry.
Out Bound Links
Overview of quartz hazards in the ceramic industry and process
Alberta Slip makes a great base for glazes because not only is it almost a complete glaze by itself but it has low thermal expansion, it works well with frits and slurry properties can be adjusted.
An amber-colored glaze that produces a clean, micro bubble free transparent glass on brown and red burning stonewares.
2003-12-12 - This is the base cone 6 Alberta Slip recipe. The 20% frit makes it melt well to form a transparent amber glossy. Frit 3134 has traditionally been ...
In Bound Links
How Alberta Slip was created by analysing and duplicating the physical and chemical properties of Albany Slip
New York Slip, Albany Clay
Plainsman Cone 6 Alberta Slip based glaze. It can be found among others at http://albertaslip.com.
2010-11-20 - Works well on all types of bodies, very reliable.
Plainsman Cone 6 Alberta Slip based glaze the fires bright blue but with zero cobalt.
2003-12-12 - This glaze creates a bright blue yet contains none of the world's most expensive common ceramic material, cobalt oxide. It has a great glossy surface ...
Alberta Slip creates a glossy transparent brown at cone 10 with the simple addition of 10% frit.
2011-08-02 - 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 need...
Alberta Slip at 60:40 calcine:raw makes a great tenmoku-like glaze at cone 10R
2011-08-02 - 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 Ten...
Calcined Alberta Slip
You can make a black glaze at cone 10R using only 1% black stain in a 100% calcine:raw mix of Alberta Slip
2003-12-12 - 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 ...
Ask yourself the right questions to figure out the real cause of a glaze crawling issue. Deal with the problem, not the symptoms.
Roasted Alberta Slip