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Alberta Slip

In 1988 we formulated Alberta Slip as the first widely available substitute material. It had the same chemistry and very similar firing properties as an average sample of Albany Slip (the material was somewhat variable). Alberta Slip has been proven over many years and is used by people across North America to make many stunning glazes. Other substitutes have appeared from time to time but no others have had the success of this material.

For more information about Alberta Slip please visit this article at digitalfire.com.

Firing

Since it is basically a clay material, it generates a significant amount of gases as it decomposes during melting. However despite this it can produce stunningly smooth and defect-free surfaces (we do not have a good explanation for this).

Glazing

Since Alberta Slip is a plastic clay it dries hard but has an associated shrinkage. It is thus an ideal base for 'slip glazes' that are used on leather-hard ware and must shrink with the piece.

The plasticity of Alberta Slip is a key advantage it has over traditional Albany Slip. Mixing raw and calcined material in the needed proportion makes it shrinkage-adjustable, it can be made to fit any application need or body. You can calcine Alberta Slip powder by firing the powder in a bisqued container to red heat and holding for 15 minutes (the calcined material has the same chemistry but no drying shrinkage). Used pure, Alberta Slip is ideal for slips that are applied to leather hard ware, however on bisque ware it will peel during drying. Start by using half raw and half calcined Alberta Slip (adjust the ratio as needed to get a compromise between needed hardness and tolerable shrinkage).

Like Albany Slip, Alberta Slip has a low thermal expansion. Thus glazes will tend to be craze free. However, if you use significant lithium carbonate as a flux with this material, be advised that it can shift the already low expansion enough to produce shivering, a hazardous situation for both user and maker alike.

Our flow tests show that Alberta Slip displays the same characteristic blistering as Albany in fast firings, however, it does not melt quite as vigorously (although it does flow as well). In addition, Alberta slip is not as inherently fine and silty as Albany. Alberta slip will tend to gel glaze suspensions a little more than Albany did and it does not deflocculate easily.

Glaze Recipes

Alberta Slip provides one of the best ways to create difficult-to-make black glazes. As little as 2-5% cobalt oxide, copper oxide, black stain, etc. can be employed to make range of excellent glossy blacks. Tom Coleman, for example, uses 30% nepheline syenite and 4.5% cobalt carbonate for a satin cone 10 black. The more fluid the glaze (i.e. more frit) the more the likelihood of crystalline effects. If minimum melter is used gunmetal black glazes can be achieved.

In the past variegated crystal green glazes were made with addition of around 5% rutile (and frit if needed). This works also with Alberta slip.

A classic cone 6 variegated brown recipe used Albany was 10 lithium carbonate, 5% tin, and 85% Albany. This works well with Alberta Slip, however like Albany, it can shiver on some bodies. You might try substituting some boron frit for some of the lithium or use a body of lower thermal expansion.

Note that this section is not intended to give you a guaranteed-to-work glaze. It focusses on the value of this material to make a base glaze and provides some examples of variations, but everyones circumstances are different, you must do testing and likely alteration for your situation. Visit this page for information on variegating, opacifying and coloring glazes: Variegating Glazes.

Cone 10 Reduction Glazes

Alberta Slip Base cone 10R Code: GA10-A
Alberta Slip used as a straight glaze at cone 10R, it looks much like a Tenmoku. Vase with 100% Alberta Slip at cone 10R Metallic deep purple by firing pure alberta slip at cone 10R, then refiring at cone 6 oxidation.	Recipe 0.00 0.00 Alberta Slip, like the original Albany Slip, melts to a beautiful glossy deep brown at cone 10R. Alberta Slip is more plastic, thus you will likely need to calcine 50% of it (and mix this with the raw powder) to get an easy-to-use slurry that will dry without cracks.

Alberta Slip Base for cone 10 oxidation Code: GA10x-A
Alberta Slip plus 10% frit 3134 fire at cone 10 oxidation.	Recipe Alberta Slip 90.00 Frit 3134 10.00 100.00

Alberta Slip Black Cone 10R Code: GA10-D
A jet a black glossy glaze is as easy as 1% black stain and 99% Alberta Slip (Mason 6666 or 6600). This is a metallic silky crystal black, it is Alberta Slip plus 5% black stain and 7% iron. A matte black made from ball milled Alberta Slip with 5% Mason 6666 stain at cone 10R.	Recipe Alberta Slip 99.00 Mason 6666 or 6600 1.00 100.00 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. Adding 5% black stain and 5-7% iron produces a crystal intense slightly metallic gunmetal black.

Alberta Slip Crystal Kaki Cone 10R Code: L3341B
Alberta slip becomes a crystal kaki at cone 10R as iron is added, here it has 3%. The effect becomes quite intense by 5%.	Recipe Alberta Slip 97.00 Red Iron Oxide 3.00 100.00

Alberta Slip Tenmoku Cone 10R Code: GA10-B

Alberta Slip used as a straight glaze at cone 10R, it looks much like a Tenmoku. Alberta slip with 1% iron and 5% calcium carbonate (right) compared to G1947U + 11% red iron oxide (left). A little more iron is needed in the Alberta Slip. G2894 Ravenscrag Tenmoku on the left (with 10% whiting and 10% iron oxide) and Alberta Slip tenmoku (center and right with 5% whiting and 1% and 2% iron added). Reduction porcelain body. G2894 Ravenscrag Tenmoku on the left (with 10% whiting and 10% iron oxide) and Alberta Slip tenmoku (center and right with 5% whiting and 1% and 2% iron added). Iron reduction body.

Recipe Alberta Slip 100.00 Calcium Carbonate 5.00 Iron Oxide 2.00 107.00 Tenmoku glazes normally contant 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 much cleaner to use and applies very evenly and suspends well.

Cone 10 Oxidation

Alberta Slip Base for cone 10 oxidation Code: GA10x-A
Alberta Slip plus 10% frit 3134 fire at cone 10 oxidation.	Recipe Alberta Slip 90.00 Frit 3134 10.00 100.00

Cone 6 Oxidation Glazes

Alberta Slip Black Cone 6 Code: GA6-H
This one inch tall mug was made using Alberta Slip plus 1% black stain and 20% frit 3134.	Recipe Alberta Slip 73.00 Ferro Frit 3134 20.00 Zircopax 4.00 Mason 6666 Black Stain 3.00 100.00 A glossy black. The small amount of frit needed is due to the fact that Alberta slip is a dark burning material already. If it is not black enough, increase the percentage of stain (and frit if it does not melt enough). Should be ball milled.

Alberta Slip Cone 6 Base Glaze Code: GA6-A

Alberta Slip fired at cone 6 using 20% frit 3134 (left) and 20% frit 3249 (right). This one inch tall mug fired at cone 5 with Alberta Slip+20% frit 3134 is similar to a cone 10 reduction celadon glaze. 80:20 Ravenscrag:Frit 3134 base ball milled on a lighter clay. Defect free fired surface of alberta slip plus 20% frit 3134 at cone 6 oxidation on a dark and light burning clay body. Ravenscrag Slip GR6-A (20% frit 3134) and Alberta Slip GA6-A (20% frit 3134) glazes on M340 at cone 5 reduction. GA6A glaze fired at cone 5R on Plainsman M350 and M340. GA6A glaze (Alberta Slip 80%, Frit 3134 20%) at cone 5R (left) and pure Alberta Slip at cone 10R (right). GA6-A at cone 5R on Plainsman M370, M350.

Recipe Alberta Slip 80.00 Ferro Frit 3134 20.00 100.00 Covers very well to produce a transparent amber glass. Should be ball milled to remove iron specks if needed. This is an excellent base glaze for many dark colors. If crazing occurs (you need to look closely for it) switch to frit 3249 low expansion frit.

Alberta Slip Cone 6 Oatmeal Code: GA6-B
Alberta slip oatmeal (80:20 base plus 6 rutile, 3 titanium left, 4 rutile, 2 titanium right)	Recipe Alberta Slip 80.00 Frit 3134 20.00 Rutile 5.00 Titanium Dioxide 3.00 108.00 Alberta slip is perhaps better suited to oatmeal glazes because it already has the iron content needed. Vary the titanium for more or less gloss.

Alberta Slip Glossy Brown Code: GA6-D
Alberta Slip glazes GA6D and GA6C. GA6-D brown Alberta Slip glaze at cone 5R. GA6D Alberta Slip, Frit 3134 glazed bowls in cone 6 oxidation (right) and cone 5 reduction (left). The variegating effect of a thin layer of titanium dioxide (outside of bowl) on GA6-D Alberta Slip glaze at cone 6 Speckled GA6-D glaze at cone 6.	Recipe Alberta Slilp 80.00 Ferro Frit 3134 20.00 Rutile 4.00 Tin Oxide 4.00 108.00 Works well on all types of bodies, very reliable.

Alberta Slip Lithium Brown Cone 6 Code: GA6-G

10% lithium and 4% tin do this to an otherwise transparent dull brown Alberta Slip. Alberta Slip in the common 11% lithium and 4% tin Albany slip cone 6 glaze. This 1 inch tall mug is glazed with Alberta Slip plus lithium, tin and some frit. The 85% Albany, 11% lithium, 4% tin oxide brown recipe using Alberta Slip (left) and reduced lithium content (G2415E).

Recipe Alberta Slip 75.00 Ferro Frit 3195 21.00 Tin Oxide 4.00 Lithium Carbonate 5.00 105.00 One of the most popular Albany Slip glazes was 11% lithium, 4% Tin and 85% Albany Slip. A portion of the Alberta Slip must be milled or the glaze will crack during drying. This recipe reduces the lithium to reduce shivering problems and it employs a frit to help melt the glaze. While it is not quite as variegated, the surface is very smooth and variation in color with thickness is still very good. This needs to be ball milled to break down the lithium carbonate particles.

Alberta Slip Rutile Blue for Cone 6 Code: GA6-C

2,3,4,5% rutile added to a 80:20 mix of Alberta Slip and Frit 3134 at cone 6 This one inch tall mug is made from Alberta Slip plus 20% frit and 4% rutile. Alberta Slip GA6C recipe on right (normal) and on left where a Boraq has been used as the flux instead of Ferro Frit 3134. The MgO is destroying the effect! Alberta Slip glazes GA6D and GA6C. GA6-C Alberta Slip rutile blue at cone 5R. Alberta Slip GA6-E with 80:20 base plus 4 rutile and 4 spodumene.

Recipe Alberta Slip 80.00 Ferro Frit 3134 20.00 Rutile 4.00 104.00 This glaze has a great glossy surface and variegates a lot going from medium steel blue where it is very thick to amber clear where it is very thin. It covers well at all thickness.

Getting a Sample

Physical Properties

 Drying Shrinkage: 5.0-6.0%

Melt Flow:

 Cone 6: 3.0-4.0 cm
 Cone 8: 5.0-6.0 cm
 Cone 10: 7.0-8.0 cm

Sieve Analysis (Tyler mesh):

     +100: 0.0-0.1%
 100-150: 0.3-0.6
 150-200: 1.5-2.5
 200-325: 4.5-6.0

Chemical Analysis

 CaO       6.5
 K2O       3.0
 MgO       3.1
 Na2O      2.2
 TiO2      0.4
 Al2O3    13.8
 P2O5      0.1
 SiO2     56.8
 Fe2O3     4.1
 FeO       0.7
 MnO       0.0
 LOI       9.3%

MSDS