Modification Date: 2015-10-30 18:48:32
Member of Group: rslip
A Ravenscrag Slip base made by simply mixing it 50:50 with a frit
|Rate (C)||Temp (C)||Hold (Min)||Step|
What is Needed:
-Plainsman Buffstone (lowfire buff burning body)
(for a class with 20 to 30 children, for two projects for each student, 2 to 3 boxes of clay will be sufficient)
-Frit 3195 and Ravenscrag slip (2.5 kg. each). Frit is a powdered glass (while mixing any dry products a respiratory mask is recommended).
-Stains. A variety of colours to enable children to paint base coat designs. Stains vary in price.
-Junior 04 cones. To bisque fire projects and glaze.
-Ravenscrag (or L213 low fire white body powder) to mix with stains (stains need to be blended with a medium)
-Plastic, newspaper, paintbrushes, and tools for children (plastic knives, straws to make holes in clay, garlic press to make hair, etc.)
Slip recipe to colour or decorate on clay surface.
70 grams of dry material (L213 body powder or Ravenscrag)
30 grams of coloured stain.
Mix with water to a cream like consistency. Apply on wet, dry or bisque surface. Mix in smaller containers so children can share at separate tables.
Some teachers have allowed children to decorate their projects with coloured slip and then bisque fired to cone 04 (they skipped glazing the projects). You would not get a glossy finish nor would the clay be sealed or capable of holding water or food, but for some hand-building projects that would not be a problem.
-After the projects have been created, allow the children to decorate the surface of the clay with coloured slips. If there was not enough time in one class to do this, their projects can be painted when the clay has dried.
-Clay shrinks 5% to 7% and, to prevent cracks from occurring, it is best to allow the clay projects to dry out on newspaper and cover with a light, dry cleaner's plastic for the first couple of days. After a couple of days, take off plastic and let air dry. Encourage even drying by turning pieces over once or twice (if the shape allows it).
-If you used any type of form inside the clay like a cardboard tube, remove it, or the clay will crack as it attempts to dry around the object. Use a layer of newspaper or cheese cloth between form and clay so it is easier to remove the form.
-Mix glaze and slip well (with an electric mixer if possible).
-When brushing on glaze, try to achieve an even layer on the bisque. Paint on one coat and allow to dry before applying the next coat. Two to three coats should be good. One coat would be too thin.
-For dipping, make sure the glaze is not too thick. It should be approximately the thickness of a credit card.
-Clay projects can be bisque fired to cone 04 and glaze fired to cone 04 as well.
-For a better melt, glaze can be mixed with 60% Frit 3195 and 40% Ravenscrag. You would need a scale to weigh the material.
Approximate costs as of 2003
$4.25 for 2.5 kg of Ravenscrag slip
$17.80 for 2.5 kg of Frit 3195
$3.50 L213 Or use Ravenscrag Slip, 2.5 kg bag
$5.90 6364 Turquoise Blue, 125 grams
$8.85 6006 Deep Crimson, 125 grams
$6.50 6267 Emerald Green, 125 grams
$14.27 Box of Buffstone (x 2)
$7.40 box of Jr. 04 cones.
Total is about $85.
Although this costs slightly more than buying premixed glazes it provides more versatile decoration process and much more glaze.
This is fired at cone 04. It is Buffstone clay with Ravenscrag:Frit 3195 50:50 glaze over stain colored slips.
This is Ravenscrag Slip, I am going to calcine about 10 pounds of it in this bisque ware vessel to destroy the plasticity. I will fire to cone 020 and hold it for 2 hours to make sure the heat penetrates. Why calcine? Because I have found that in some glazes having 70% or more Ravenscrag Slip, cracking on drying can occur if it is applied too thick. I love the working properties of these glazes and want to optimize them to avoid any problems. I am going to mix 75:25 raw:calcine on the next batch of glaze. However, Ravenscrag 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 750 raw and 250*.91=227.5.
Out Bound Links
In Bound Links
There are many things to know about to make the best use of stains, but one often ignored aspect is ...
Understanding the advantages of disadvantages of stains vs. oxide colors is the key to choosing the ...
By Tony Hansen