Modification Date: 2015-10-30 18:56:19
Member of Group: AS6
Plainsman Cone 6 Alberta Slip based glaze. It can be found among others at http://albertaslip.com.
|Alberta Slip Calcined||40.0||37.0%|
Alberta slip is well suited to oatmeal glazes because it already has the iron content needed. Vary the titanium for more or less gloss and oatmeal appearance.
This glaze is very attractive, but one issue you might encounter is pinholing or blistering if it is too thick (a common problem with this type of glaze). Try using it on different bodies and thicknesses to find the best combination. Adjust the frit if you would like it to melt lower or higher. Do not hesitate to reduce the rutile and titanium by a percent to experiment. Getting this glaze working is well worth the effort, not just for the fired results, but for how well it works in the studio. It is actually less troublesome than most others that fire similarly.
This recipe was referred to as GA6-B in past.
The 80:20 base Alberta slip base becomes oatmeal when over saturated with rutile or titanium (left:6% rutile, 3% titanium; right:4% rutile, 2% titanium right). That oatmeal effect is actually the excess titanium crystallizing out of solution in the melt as the kiln cools. Although the visual effects can be interesting, the micro-crystalline surface is often susceptible to cutlery marking and leaching. This is because the crystals are not as stable or durable as the glass of the glaze.
The underglaze is G1214M cone 6 black (adds 5% Mason 6666 black stain). Overglaze left: GR6-H Ravenscrag Oatmeal. Overglaze right: GA6-F Alberta Slip oatmeal. Both produce a very pleasant silky matte texture (the right being the best). Both layers are fairly thin. In production it would be best to spray the second layer, keeping it as thin as possible. It is also necessary to adjust the ratio of raw to calcined Alberta or Ravenscrag Slips to establish a balance between drying hardness but not too much drying shrinkage (and resultant cracking).
Calcined Alberta Slip (right) and raw powder (left). These are just 5 inch cast bowls, I fire them to cone 020 and hold it for 30 minutes. Why calcine? Because for glazes having 50% or more Alberta Slip, cracking on drying can occur, especially if it is applied thick (Alberta Slip is a clay, it shrinks). I mix 50:50 raw:calcine for use in recipes. However, Alberta Slip has an LOI of 9%, so I need to use 9% less of the calcine powder (just multiply the amount by 0.91). Suppose, I needed 1000 grams: I would use 500 raw and 500*.91=455.
Out Bound Links
Plainsman Cone 6 Ravenscrag Slip glaze. See more at ravenscrag.com.
2003-07-21 - Note: For use as a straight glaze We are recommending GA6-F Alberta Slip oatmeal glaze instead, it looks better and has a better melt. Alberta ...
By Tony Hansen+