'ARTIST CHOICE'

STONEWARE  SLIP

     Creating with stoneware is an exciting and rewarding challenge. Stoneware clay gives us the opportunity to create ware of understated elegance and subtle beauty. Superior kitchenware and decorator items, cast in stoneware, have rich earthy colors. Stoneware has a "look" and a "feel" that cannot be duplicated in a ceramic body.

     Pieces that are meant to be used and enjoyed through the years are quite often cast in stoneware slip because of its durability. Artist Choice Stoneware slip matures for use as ovenware or tableware and will hold water without glazing at cone 5. It is completely vitrified at cone 6. Kitchenware can be used in the oven or in a microwave. It is very easy to cast, will not stain the molds and is clean draining.

        Shrinkage is 11-12% and the slip is non-toxic.

      Color chart will be on the website when the available choices have been determined.

 

 

   
   
   

 

SLIP PREPARATION

Stoneware slip must be stirred until it is smooth and completely mixed. This can best be accomplished by removing slip from jar and pouring into the utensil you plan to use for casting. Stir, preferably by hand with a large round stick, until it is thoroughly mixed and very smooth. Large quantities may require the use of an electric drill equipped with a Jiffy Mixer blade. Allow slip to set until air bubbles that were introduced during the mixing process come to the surface. The slip will be thick before mixing, but will thin out as it is mixed. If slip is too thick for proper casting, thin with a few drops of Slip Thinner and a teaspoon of distilled water. Do not add more than a few drops of the Slip Thinner or your greenware will develop a scum making the ware very hard to clean in the dry state. If this should happen, fire to cone 018 before cleaning.

CASTING

When choosing molds for casting in a stoneware body, remember you will have a 11 % to 12% shrinkage from mold size to fired piece. Choose molds that are designed for this shrinkage. No one wants a 12" dinner plate that comes from the kiln at 10"! Crest Molds has a complete dinnerware set, soup mugs, casseroles, bean pots and many other items that have been designed to allow for this shrinkage. Molds must be clean and free from any ceramic clay. Fill mold slowly just as you would cast ceramic slip. Set up time is about the same as with ceramic slip, but you may wish to cast stoneware greenware a bit thicker. Drain slowly and do not allow the mold to "glug" or suck air. Trim with a sharp knife as soon as slip quits draining. After trimming allow casting to remain in mold until it is leather hard. This takes about as long as a ceramic casting. If at any time during removal from mold the clay seems wet, wait a little longer before removing, as any distortion will be visible after firing. CAUTION: Stoneware, like Porcelain has a "memory". If the greenware is distorted while wet, even though you think you have "fixed" it, the casting will go back to the same warped condition during firing. Also do not dry casting in half of the mold. This will cause uneven shrinkage and ware can warp in firing. Do not force dry the stoneware castings.

CLEANING

Stoneware greenware is as easy to clean as ceramic greenware. It is not as fragile as Porcelain. Ware can be cleaned in the damp state or when it has become completely dry. Use a sharp clean up tool to remove seamlines, sand with a grit sponge and then finish by sponging with a damp sponge. Extra care should be taken to leave the surface perfectly smooth as in many cases you will not be applying a glaze to the outside surface and any imperfections will be visible after firing.

DECORATION

All underglazes and glazes are applied on greenware or low fired bisque. Low fired bisque is clay that has been fired in the range of cone 019 to cone 017. This will enable you to decorate and glaze the inside of piece without fear of breakage.   The underglaze colors usually develop a slight shine in the firing. Underglazes need no covering glaze when fired to stoneware temperature. Glaze the insides of food utensils just as you would on a ceramic body. Glaze can be applied by brushing or by roll glazing.

When glazing on the outside of a piece, remember, stoneware can not be stilted so all ware must be dry footed. We recommend that dry footing be extended up the sides of a piece for as much as 1/4". Glaze that is to be used on stoneware should be thinned to the consistency of light cream. Apply the usual 3 coats but do not apply heavily. Stoneware shrinks, thereby causing the glaze to condense and become thicker, making it is easy to apply too much glaze.   A glaze that is listed as food-safe at a cone 06-05 firing will also be food-safe at cone 6. Always test fire a small piece of any underglaze or glaze so you will be able to predict the outcome of your decorating.

Fired Metals, Glass Colors and decals can be applied directly to the stoneware bisque.

FIRING

Kiln shelves should be smooth and level. Apply a new coat of kiln wash to the shelves if they have not been coated recently. Also apply kiln wash to cone supports and the sensing rod on the kiln guard. When firing the kiln to cone 5-6 for the first time it will be necessary to use witness cones on each shelf to check for areas that are cooler or for hot spots. Ware should be thoroughly dry before loading. Glazed ware should be fired on one shelf and unglazed ware should be fired on another to prevent flashing, a phenomenon that can occur in a high fire. Flashing is when glazes transfer to nearby pieces causing a glossy spot to form on adjoining ware. Do not stilt! Lids must be fired on casseroles, act. Check lids and container rims for glaze on surfaces that will touch during firing. When firing to cone 5, it will not be necessary to use a separator on these lids. If you prefer the slight shine and the complete vitrification of cone 6, you will need to apply 1 coat of Separator to surfaces that will touch. Firing to cone 5 will mature this clay, leaving just enough porosity to allow for thermal shock when using for ovenware. There will also be less distortion, less flowing of outside glazes and less shine on the stoneware bisque at cone 5. Handles on cups, act. may need propping with high fire fiber as is necessary with porcelain. A slower firing schedule is recommended when firing stoneware and porcelain. Kiln lid should be propped until kiln is turned to high.