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GA6-A - Oringal Alberta Slip Amber/Honey base

Modified: 2023-09-16 16:22:37

An amber-colored glaze that produces a clean, micro bubble free transparent glass on brown and red burning stonewares.

Material	Amount
Alberta Slip 1000F Roasted	40.00
Alberta Slip	40.00
Ferro Frit 3134	20.00
100.00

Notes

Don't use this glaze anymore as a transparent honey, use GA6-B instead (it produces a better glass and is more durable by virtue of higher Al₂O₃ and SiO₂ content).

The was a long-time cone 6 base recipe for Alberta Slip. For this and the GA6-B we recommend a 2% iron oxide addition to get a richer color. Fusion Frit F-12 has proven a good substitute for 3134.

This version is still needed for a couple of reasons:

1. This one produces rutile blues in the cool-and-soak C6DHSC firing schedule (likely because this has a lower Al₂O₃ level, enabling the crystallization of the TiO2 in the rutile).

2. This is also the only version that crystallizes in slow cool firings (e.g. the C6DHSC schedule).

Related Information

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 GA6-B base darkened with iron oxide

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.

A cone 6 clear glaze plus iron vs. Alberta Slip amber base

These two mugs are made from a dark red burning stoneware and fired in a cool-and-soak firing schedule. A white engobe (L3954A) has been applied on the inside and half way down the outside. Both are glazed inside with G2926B whiteware transparent glaze. The outside glaze on the left is the same transparent with 4% added iron oxide. It has been sieved to 80 mesh. Notice the iron agglomerates and still produces specking (an effect that may be desired, but difficult to keep consistent). Interestingly, that iron is producing a clear amber-colored glass about equal in color to the Alberta Slip GA6A base glaze (80% Alberta Slip, 20% Frit 3195) on the mug on the right. Neither has the micro bubbles that mar a typical clear glaze on bodies like this.

A transparent that looks good on cone 6 red burning bodies

The GA6-A Alberta Slip:Frit 3134 (80%:20%) glaze is excellent as a liner for dark burning bodies, it looks much better than a regular transparent recipe (which often form clouds of bubbles on red bodies). The iron in this glaze makes it fire an amber color on buff burning bodies (not very attractive), but on red bodies it brings out the natural color of the clay.

Plainsman dark bodies with Alberta Slip floating blue

Cone 6 mugs made from Plainsman M350 (left) and M390 dark burning cone 6 bodies. The outside glaze is Alberta-Slip-based GA6-C rutile blue and the inside is GA6-A base (20% frit 3134 and 80% Alberta Slip). That inside glaze is normally glossy transparent amber, but crystallizes to a stunning silky matte when fired using the C6DHSC schedule.

Thin titanium band sprayed over cone 6 glazes demonstrates crystallization

The first is on GA6-A, the rest are on GA6-C (Alberta slip glazes). The last has been applied too thickly, the brown band is dry and blistered.

Crystallization of this glaze gives insight into why it can host the floating blue effect

These two mugs have the Alberta Slip base cone 6 GA6-A glaze on the inside and GA6-C on the outside (it just adds rutile to GA6-A). The left one was cooled normally (kiln off at cone 6 after soak). For the mug on the right, the kiln was soaked for half an hour at 1800F on the way down to develop the rutile blue glaze on the outside. But during this period crystallization occurred on the inside also. This provides an insight into my this GA6-A base hosts floating blue effects but GA6-B does not: The amount of Al₂O₃ is much lower, that improves melt fluidity and acts as a catalyst for crystallization.

A typical transparent glaze vs. Alberta Slip amber base vs. a on a red burning cone 6 body

The body is Plainsman M332, a coarse particled brown to red burning cone 6 body. With the G2926B transparent cone 6 glaze (left) and the GA6-A Alberta Slip base (right). The latter brings out the color of the body much better, the former is milky, bubbly and yucky!

Tin oxide stops crystallization in GA6-A Alberta Slip base glaze

Both of these mugs were soaked 15 minutes at cone 6 (2200F), then cooled at 100F per hour to 2100F and soaked for 30 minutes and then cooled at 200F/hour to 1500F. This firing schedule was done to eliminate glaze defects like pinholes and blisters. Normally the GA6-A glaze crystallizes (devitrifies) heavily with this type of firing, but an addition of 1% tin oxide to the one on the left has prevented this behavior.

GA6A Alberta Slip base using Frit 3124, 3249 and 3195 on dark body

The body is dark brown burning Plainsman M390 (cone 6). The amber colored glaze is 80% Alberta Slip (raw:calcine mix) with 20% of each frit. The white engobe, L3954B, on the inside of two of the mugs is L3954A (those mugs are glazed inside using transparent G2926B). The Alberta Slip amber gloss glaze produces an ultra-gloss surface of high quality on mugs 2 and 3 (Frit 3249 and 3195). On the outside we see it this glaze on the white slip until midway down, then on the bare red clay. The amber glaze on the first mug (with Frit 3124) has a pebbly surface. These are fired using a drop-and-soak firing schedule. Some caution is required with the 3249 version, it has low thermal expansion (that is good on bodies that normally craze glazes, but risks shivering on ones that do not).

GA6A Alberta Slip base using Frit 3249 and 3195 on buff body

The body is buff burning Plainsman M340 (cone 6). The amber colored glaze is 80% Alberta Slip (raw:calcine mix) with 20% of each frit. The white engobe on the inside of mug 1 is L3954A (also glazed inside using transparent G2926B). These frits are producing an amber gloss glaze of high quality. On the outside of mug 1 we see the 3195 version on the white slip until midway down, then on the bare buff clay (the other has the 3249 version). These mugs are fired using a drop-and-soak firing schedule. A couple of caveats: Frit 3249 has a very low thermal expansion, use it on bodies that craze other glazes (like Plainsman P300), it could shiver on stonewares like this. Both of these frits prevent the formation of bloating blues (with additions of rutile or titanium).

A white engobe on dark and buff burning cone 6 stonewares

Left is Plainsman M340. Right is M390. Each mug has been white-engobed inside (by pouring), using L3954B, and halfway down the outside (by dipping). The insides have been glazed using G2926B clear. The inside surface has more depth and a richer appearance than could be achieved using a white glaze (especially over the dark burning body). The outside of the left one is Alberta Slip base GA6-B. The outside glaze on the right is the clear plus 4% iron oxide. This technique of using the engobe enables porcelain-like functional surfaces on the insides and the visual contrasts and character on the outsides of the stoneware mugs.

Same glaze, same kiln, same clay: The right one crystallized. Why?

Well, actually they are not exactly the same. This is 80% Alberta Slip and 20% frit. But the frit on the left is Ferro 3195 and on the right is 3134. By comparing the calculated chemistry for these two we can say that the likely reason for the difference is the Al₂O₃ content. Frit 3134 has almost none whereas 3195 has 12%. Al₂O₃ stiffens the glaze melt, that impedes crystal growth. And it stabilizes the melt against running during firing. Frit 3195 is thus much more "like a glaze" than is 3134, it is what Alberta Slip needs to melt as a transparent glass under normally cooling in the kiln.

Links

Recipes	GA6-H - Alberta Slip Cone 6 Black Pure Alberta Slip can be made into a black adding only 20% frit and 3% black stain
Recipes	GR6-A - Ravenscrag Cone 6 Clear Glossy Base This Plainsman Cone 6 Ravenscrag Slip base is just the pure material with 20% added frit to make it melt to a glossy natural clear.
Recipes	GA6-B - Alberta Slip Cone 6 transparent honey glaze An amber-colored glaze that produces a clean, micro-bubble-free transparent glass at cone 5-6. Works well on brown and red burning stonewares.
Recipes	GR6-B - Ravenscrag Cone 6 Variegated Light Glossy Blue Plainsman Cone 6 Ravenscrag Slip based glaze. It can be found among others at http://ravenscrag.com.
Recipes	GA6-G1 - Alberta Slip Lithium Brown Cone 6 Low Expansion Plainsman Cone 6 Alberta Slip based glaze. It can be found among others at http://albertaslip.com.
Recipes	GA6-F - Alberta Slip Cone 6 Oatmeal Plainsman Cone 6 Alberta Slip based glaze. It can be found among others at http://albertaslip.com.
Recipes	GA6-D - Alberta Slip Glossy Brown Cone 6 Plainsman Cone 6 Alberta Slip based glaze. It can be found among others at http://albertaslip.com.
Typecodes	Alberta Slip Glaze Recipes Alberta Slip is a substitute for Albany Slip that has gained a life of its own so that there are now many glazes based specifically on it.
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.
URLs	http://albertaslip.com AlbertaSlip.com
Articles	Concentrate on One Good Glaze It is better to understand and have control of one good base glaze than be at the mercy of dozens of imported recipes that do not work. There is a lot more to being a good glaze than fired appearance.

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