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Albany Slip

Alternate Names: New York Slip, Albany Clay

Description: High iron silty low melting clay

Oxide Analysis Formula
CaO 5.81% 0.48
K2O 3.20% 0.16
MgO 2.71% 0.31
Na2O 0.80% 0.06
TiO2 0.40% 0.02
Al2O3 14.63% 0.66
SiO2 57.82% 4.42
Fe2O3 5.21% 0.15
LOI 9.41%n/a
Oxide Weight 416.11
Formula Weight 459.33

Notes

Albany was a low plastic silty clay that was mined in Albany, New York for many decades. It melts to a glossy chocolate brown glaze at cone 8-10. It was a very popular glaze ingredient for dark colors and tenmoku and iron crystal effects. In the early 20th century it was used extensively on heavy utilitarian stoneware across North America and even on electrical insulators. Glazes could be formulated very easily using this material as a starting point since it was already balanced and had good slurry properties. Potters especially adopted this material and it appears in thousands of recipes used across North America.

There are a number of substitutes for Albany and anyone with ceramic chemistry calculation software can easily speculate on a mix of materials that matches the chemistry on paper. However keep in mind that judging the similarity to Albany is a complex issue of mineralogy, physical properties and chemistry and it depends on the reliability of the information at hand on what Albany actually was.

Related Information


Lithium, albany glaze at cone 5 using original albany slip

Melt fluidity of Albany Slip vs. Alberta Slip at cone 10R


Albany vs Alberta Slip melt

Albany Slip was a pure mined silty clay that, by itself, melted to a glossy dark brown glaze at cone 10R. By itself it was a tenmoku glaze. Alberta Slip is a recipe of mined clays and refined minerals designed to have the same chemistry, firing behavior and raw physical appearance (but not plasticity). This is a GBMF melt flow test showing them side-by-side.

Albany Slip DFAC dried disk


This shows the soluble salts in the material and the characteristic cracking pattern of a DFAC test disk when made from a low plasticity clay. Notice the edges have peeled badly during cutting, this is characteristic of very low plasticity clays.

90:10 Albany:Frit and Alberta:Frit comparison


These are three runs of Alberta Slip being compared with the original Albany Slip. These are ten-gram GBMF test balls fired on porcelain tiles at cone 6. This test shows how the material flows, how much gases of decomposition it generates and how well it allows them to escape. As you can see, they are very similar in melting behavior.

Melt fluidity and coverage: RedArt Slip vs. Albany Slip vs. Alberta Slip


Melt fluidity testers show similar flow but the amber clear glaze on the mugs shows some differences

These three melt flows and mugs were fired at cone 6 (using the C6DHSC firing schedule). The benchmark recipe is 80% clay and 20% Ferro Frit 3195. The center melt flow and mug (made from a Plainsman 3D-based stoneware) employs the original Albany Slip as the clay portion. The one on the far left uses an Albany Slip substitute that was developed by calculating a mix of RedArt and other materials to have the same chemistry as Albany Slip. The one on the right employs Alberta Slip. Notice that, although the Alberta Slip version has a very similar melt flow, on the mug it is apparent that it needs a little iron oxide for a better match (e.g. 1-2%). And the glaze on the left: The chemistry of RedArt is different enough from Albany that some compromises in chemistry-matching were needed to avoid over-supplying the iron even more (and firing even darker than this). Although this Redart version runs in a very similar pattern on the melt flow, the character of the glaze is somewhat different on the mug (a better match can be achieved by increasing the frit percentage slightly or firing to cone 7).

Alberta Slip GA6-B base darkened with iron oxide


Glazed tiles showing darkening with increased iron additions to GA6-B

Fired to cone 6 using the C6DHSC schedule. Top: GA6-B. This recipe is 80% Alberta slip and 20% Ferro Frit 3195 (we used to use frit 3134 but have found frit 3195 works much better). Bottom: We added 1, 2, 3 and 4% iron oxide. At about 2%, the color matches the rich reddish effect you would get if you used an 80:20 Albany:3195 recipe (without an iron addition). An added benefit is that the iron acts as a fining agent to remove micro-bubbles to achieve better transparency.

Albany Slip glaze inside mother nature's porcelain mug


Outside glaze is G2934Y black. Inside is 80% Albany clay and 20% Ferro Frit 3195, a really stunning glaze! I used the C6DHSC firing schedule. The body is a natural porcelain that vitrifies beyond the zero porosity point, producing incredibly strong ware. Yet it does not warp during firing.

Here is why Albany Slip was hard to use


This glaze is 85% Albany Slip and 20% Ferro Frit 3195. These bisque tiles were dipped in a brushing glaze version of it. Thin application on front tile, normal thickness on back one. The material gels slurries and requires a lot of water to create a usable slurry.

A classic Albany glaze that often shivers


These mugs have experienced very serious shivering. This is an Albany Slip glaze with 10% lithium carbonate, it is known to have a very low thermal expansion. This problem can be solved by reducing the amount of lithium or adding high-expansion sodium or potassium. However these fixes will likely affect the appearance.

Melt fluidity of Albany Slip vs. Arroyo Slip at cone 10R


Amaco achieves the stunning look of PC-32 Albany Brown glaze using lithium


Lithium albany brown glaze

Left is G3933A, an Alberta Slip based glaze. Right is Amaco PC-32, Albany Slip Brown. They are likely using a similar base recipe, but the difference is added lithium carbonate to supercharge the melting. That converts it to a type of reactive glaze (one that changes its appearance with differing thicknesses). Where thick in the recesses it crystallizes to a much lighter color. On contours, it runs thinner amplifying the brown body color. The use of lithium explains why PC-32 is more expensive. Lithium prices are rising so fast it may not continue to be practical for manufacturers to continue making some lithium glazes (hopefully this one is safe since the percentage is relatively low).

Links

URLs http://www.sheffield-pottery.com/Albany_Slip_Substitute_and_Sheffield_Slip_s/189.htm
Sheffield Slip substitute
URLs http://albertaslip.com
AlbertaSlip.com
URLs http://albanyslip.com
AlbanySlip.com
Materials Jasper Slip
Materials Barnard Slip
Materials SG-328
Materials Ohio Slip
Materials Arroyo Slip
Materials Sheffield Slip
Materials Alberta Slip
Albany Slip successor - a plastic clay that melts to dark brown glossy at cone 10R, with a frit addition it can also host a wide range of glazes at cone 6.
Materials Ravenscrag Slip
A light-colored silty clay that melts to a clear glaze at cone 10R, with a frit addition it creates a good base for a wide range of cone 6 glazes.
Materials Odenwalder Clay
Materials Fremington Clay
Typecodes Clay Other
Clays that are not kaolins, ball clays or bentonites. For example, stoneware clays are mixtures of all of the above plus quartz, feldspar, mica and other minerals. There are also many clays that have high plasticity like bentonite but are much different mineralogically.
Recipes GA10x-A - Alberta Slip Base for cone 10 oxidation
Alberta Slip creates a glossy transparent brown at cone 10 with the simple addition of 10% frit.
Recipes GA10-A - Alberta Slip Base Cone 10R
Alberta Slip at 60:40 calcine:raw makes a great tenmoku-like glaze at cone 10R

Data

Sieve Analysis Wet on 60 mesh: 0 on 120 mesh: 1.0% on 200 mesh: 5%
Frit Softening Point 1170C
By Tony Hansen
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