Duncan University Course

Transcription

1 The focus of Essentials 102 is Cover-Coat Opaque Underglazes and EZ Stroke Translucent Underglazes products primarily designed for greenware application. Both product families have a wide variety of uses, are easily used and will give fantastic results. Cover-Coats (CC) are an opaque underglaze designed for application on greenware. These products are clay based and need 3 coats to achieve opaque coverage. They do not move in firing. In most cases, this underglaze is applied before a glaze is applied over it. General Characteristics: 1. Water-based, water cleanup. 2. Nontoxic and food-safe when glazed with a nontoxic food-safe glaze. They are suitable for schools and institutions. 3. Brush 3 coats of color in one direction as smoothly as possible to achieve opaque non-streaked coverage. To sponge, pounce 3 solid coats over the area to create an opaque textured coat of color. 4. Designed for overall coverage without movement during firing. 5. Should be fired before being glazed. 6. Should not be stilted when fired before being glazed. 7. Cover-Coats need to be fired to shelf cone May be high-fired to cone 6 or cone 10. There will be some color change. Make a comprehensive test piece when you are going to high-fire Cover-Coats. 9. Since colors are opaque, 3 coats of one color will completely cover another color. 10. With most Cover-Coat techniques, glazing is needed to properly complete and protect the project. 11. After firing, other product families may be applied over Cover-Coats. 12. EZ Strokes may be applied over unfired Cover-Coats. 13. Colors may be mixed together to create more shades. 14. If Cover-Coats are used on bisque, for best results refire the ware to shelf cone 04, glaze and fire to the proper glaze temperature. 15. This product is suitable for airbrushing. 16. This product is good for Sgrafitto techniques. 1

2 EZ Strokes (EZ) are a translucent underglaze product designed for brushwork on greenware. These products are pigment-based and very concentrated. Product does not move in firing. General Characteristics: 1. Water-based, water cleanup. 2. Nontoxic and food safe when glazed with a nontoxic food safe glaze. They are suitable for schools and institutions. 3. Translucent and other colors applied under the EZ Strokes will show through the applied color. 4. Designed for brushwork and fine detailing, and can be layered for variations in techniques. 5. Will not flow during firing. 6. Color is very true to application. What you see is what you ll get. 7. Generally 1 coat of color is sufficient. Thin, layered applications are acceptable if they re not applied too heavily. 8. Color is generally used as is from the bottle, since colors are premixed and ready to use. However, with some colors, thinning with water is important. Usually the brown family will need additional thinning and mixing. 9. Too thick of EZ Strokes can cause the color to lift off the ware s surface during firing. 10. Colors can be mixed with other EZ Strokes to form a variety of colors. 11. When applied to greenware, fire to shelf cone 04 and then glaze with desired glaze. 12. May be applied to cone 04 bisque. Fire to at least cone 04 before glazing. 13. May be used for Majolica techniques. 14. Can be used for washes and antiquing. 15. EZ Strokes may be fired to a cone 10. Some colors will change, so a test piece should always be made. 16. EZ Strokes are excellent for airbrushing. 17. Unglazed EZ Strokes do not need to be stilted.

3 French Dimensions (FD) are an opaque, raised stand-up glaze that does not flatten out when fired and glazed. Product can be purchased in a variety of colors. 1. Product is in a squeeze bottle with a writer tip. 2. Water-based, water cleanup 3. May be applied over: a. unfired and fired Cover-Coats b. unfired and fired Concepts c. unfired and fired EZ Strokes d. Over Satin Glazes e. Under Gloss Glazes f. Over and under Courtyard Art Glazes 4. May be mixed with EZ Strokes for additional colors. When mixed with EZ Strokes, they will be opaque. 5. Can be thinned with water or Thin n Shade. 6. General firing temperatures range from cone 06 to cone Pure White FD is great for filling holes in bisque Mask n Peel (SY) is a specialty latex used for protecting an area and then removing to decorate. This product must be removed before firing. 1. A latex product that contains ammonia. 2. Brushes need to be conditioned with Brush Cleaner or non-antibacterial liquid soap. Soaps that work are bar soap, shampoo, dish soap and hand soap. Pinch out excess soap before loading brush. Too much soap will prevent the Mask n Peel from drying properly. 3. Apply Mask n Peel heavily and allow plenty of drying time. If Mask n Peel is applied too thin, the product is difficult to remove. 4. Wash brushes thoroughly and immediately when finished.

4 General Applications and Techniques: 1. Cover-Coats Opaque Coverage: a. Apply 3 flowing coats with a soft brush b. Always use the largest possible brush for the area c. Apply Cover-Coat in same direction and flow the color on. Do not over brush the color application d. Color should lose it sheen before apply the next coat. e. Brush out all drips and runs: these will not flatten out or disappear. Truffle Box and Paisley Five-Sided Plate have opaque coverage 2. Cover-Coats Opaque Coverage in Design: a. Apply the Cover-Coat as above. b. Apply the design with at least 3 coats of color. c. 3 coats of the lighter colors will block out a dark opaque background. d. Design can be detailed with EZ Strokes over the Cover-Coat. Truffle Box is completed with Cover-Coats in design over a dark base-coated Cover-Coat. Detailing is applied with EZ Stroke. 3. EZ Strokes in Design: a. When doing brushwork, all colors need to be of the same consistency to ensure proper loading. b. Load brush of choice in one color, side load in another color and maybe tip in a third. c. Blend the colors on the brush by pulling on a clean area of the palette. d. Press, pull and lift colors in place on the piece. The more pressure on the brush, the wider the stroke and the more blended the look. e. 1 coat is sufficient when working with EZ Strokes. Paisley Five-Sided Plate design work has EZ Strokes in Design and Sgrafitto with French Dimensions Dots. 4. Marbleizing with Cover Coats: a. Cover-Coats are thinned slightly with Thin n Shade and mixed with a palette knife b. Brush of choice is conditioned with Thin n Shade. c. Several colors are picked up on Round brush and drizzled off the brush onto the ware. d. The process is repeated until the colors drip and run over the entire piece. e. One pass is enough as long as the coats are applied heavily enough. Marbleized Eggs use this technique.

5 Uses for EZ Strokes Various Terms and Techniques with EZ Strokes and Cover Coats: Over other underglazes EZ Stroke colors are very effective when applied over each other or over opaque underglazes. They can be used in design over sponged or stippled color, and over solid color backgrounds. Colors are translucent and may be altered by the color underneath. Airbrushing The concentrated color strength of EZ Stroke colors is ideal for use in airbrush decoration. Thin the color with water, using 2-3 parts water to 1 part color. Airbrush onto greenware, passing over area until intensity of color on the ware is equivalent to the color in the jar. Banding Banding is applying uniform circular bands of color on pieces that are generally symmetrical in shape (platters, cups, vases, etc.). Center piece on a banding wheel and weigh it down (if possible) by inserting a plastic bag containing sand. Turn the wheel slowly with one hand while adding color with a steady hand on the brush. EZ Stroke colors are ideal for banding. Thin color to a milk consistency, and band on greenware or over another base-coat color. Spattering Thin EZ Stroke color to milk consistency and flick the bristles of a stiff brush with your finger to spatter color onto the base-coated or decorated greenware item. An old toothbrush also works well. Sponging Place some EZ Stroke color on a glazed tile, add water or Thin n Shade, and mix to the consistency specified by the technique. Spread the color shallowly over the tile with a palette knife. Use a slightly dampened sponge to apply 1 coat of color directly to greenware or over a base-coat color in patterns or to create background area, letting the underlying surface show through here and there. More than one color can be sponged on a single item. Stenciling An easy way to add shapes on any surface, including greenware or bisque, or over a basecoat color. Hold the desired stencil against the surface with fingers or tape. Load a slightly dampened brush or sponge with color, and apply through the stencil with swirling, straight or pounced strokes. To stencil with EZ Strokes, thin the EZ Stroke color with water or Thin n Shade to the consistency of thin cream. Apply 1 coat of the thinned color through the stencil opening with a sponge or brush onto greenware or over a background color. Stippling Place an EZ Stroke color on a glazed tile and thin with water or Thin n Shade to a milk or light-cream consistency. Use a Deerfoot Stippler brush to stipple color with quick, up-and-down pouncing strokes to greenware or background color. Antiquing To use EZ Stroke as an antiquing medium, mix the color with water to make a thin wash. Use a small, unwaxed cup and a palette knife to mix the color. Do not thin the entire jar. Apply the wash color to shelf cone 04 bisque, using as large a brush as is practical. Wipe down with a dampened sponge to remove excess color from raised areas. Clean the sponge frequently. When the piece is dry, apply clear glaze and fire to shelf cone 06. Always make a newspaper test before applying to the ware.

6 Over a glaze (Majolica) EZ Stroke colors can be used over unfired glazes and fired to shelf cone 06. Designs, patterns or scenes can be painted over nonmoving glazes. Thin EZ Stroke colors to a consistency no heavier than light cream and apply 1-2 light coats. Too heavy or too thick an application may produce a textured effect or blisters on the color area. Unusual effects can be obtained when EZ Stroke is applied over flowing glazes such as glosses. The colors will change somewhat, depending on the glaze, the shape of the bisque piece and the cone to which it is fired. As the glaze flows, the EZ Stroke will also flow. Bisque Application Use EZ Stroke on shelf cone 04 bisque when an antiqued effect is desired. Lightly dampen the bisque with clean water before applying EZ Stroke. Bisque is very porous. Unless it is dampened, it will absorb the moisture from the color too readily, making it impossible to achieve a smooth stroke. It is not necessary to fire decorated bisque before applying a glaze, provided the EZ Stroke color is not disturbed. There will be slight color variations between EZ Strokes fired to cone 06 and to shelf cone 04. All EZ Stroke colors will work on bisque. Some darker colors are more sensitive to smearing under clear glaze, and a few will crack if applied too heavily. As a colorant EZ Stroke colors can be blended to create additional colors. They can also be used to tint Fired Snow. The usual proportions are equal parts EZ Stroke and Fired Snow. EZ Strokes are ideally suited to marbleize ceramic, porcelain or stoneware casting slip. Fire a small test piece to determine the proper mixture for the desired effect. Uses for Cover-Coats Brushwork Cover-Coats are fantastic for a variety of brushstrokes. Thin color slightly and apply 1 coat, thus generating a translucent look. 2 to 3 coats will generate a more opaque look. Sponging Dip a slightly dampened sponge into the color and sponge on 3 even coats, using an up-and-down pouncing motion. One coat of another color can be sponged here and there over the first coat to give a multicolored effect. Airbrushing Thin the color with water (equal amounts color to water). Airbrush the thinned color onto the greenware, passing over the desired area until the intensity of the color on the ware is equivalent to the color in the jar. Sgraffito This technique is a method of creating a design by gently scratching through the unfired underglaze color or nonmoving glaze applied to the ware to reveal another color or the clay body beneath it. Because sgraffitoing is best done while the color is still damp, work quickly to sketch or trace a design over the unfired underglaze color. Work with one small area of your design at a time. To avoid chipping the color, always pull the tool away from a point on each side of the previously sgraffitoed line. If the color becomes too dry, moisten the area to be sgraffitoed with a slightly dampened sponge, being careful not to over-dampen the piece. Apply the color by brushing or sponging, and then sketch on the design. While color is still damp, use the Sgraffito-Duster tool with the hollow side of the blade down to gently scratch fine shallow lines along the design lines, for deeper lines go over a few more times to gradually deepen and widen. Use the brush end of the Sgraffito-Duster tool to remove dust and clay particles from the sgraffitoed lines. Bisque fire the ware to witness cone 04 and apply the desired glaze.

7 Polished finish This nonglazed finish is used on nonutility items. Apply the color as directed under brushing or sponging application, then apply another coat of the color thinned half and half with water to a small area of the greenware at a time. When the wet look disappears from the newly painted area, polish it briskly with a soft cloth until a sheen is obtained. Overlap the areas slightly so that no unpolished spots will remain. When the entire surface of the ware is polished, bisque fire it to shelf cone 04. No additional finish is required. This project is not waterproof, but it is dirt resistant and can be washed. However, allow the piece plenty of drying time before setting on furniture. High-fire porcelain and stoneware application When thinned with water or Thin n Shade to a milk consistency, many Cover-Coat colors can be applied to porcelain and stoneware, and fired to the maturing cone recommended by the high-fire slip manufacturer, shelf cones 4 to 6. At these temperatures, most Cover-Coats will undergo a color change. Test firing is recommended or refer to the Colorworks Catalog. The surface may also change. Some Cover-Coat colors become highly glossy, some attain a slight sheen and some fire to a completely matte finish. All the Cover-Coats bond firmly to the ware and create some very beautiful effects. Cover-Coats: Troubleshooting and Problem Solving 1. The Cover-Coat has tiny hairline small cracks in recessed areas of a detail piece. a. The Cover-Coat was applied too heavily and not brushed out of the recessed areas. b. In the future, thin the Cover-Coat down when working on a detailed piece. 2. When glaze fired, the Cover-Coat appears to have white or light-colored streaks in it: a. The Cover-Coats were not applied heavy enough and one is seeing the white of the ware through the under-applied color. b. In the future, do not overly thin the Cover-Coat. c. Do not overbrush the color during application; flow the color on and reload often. d. The third coat was not applied; one lost count of the number of coats applied. 3. Drips and ridges seem to show up after the first firing and then, when glazed, they still show. a. The Cover-Coat were not applied smoothly, and these drip marks were not brushed out when color was applied. b. Brush out drips and runs for Cover-Coats, as they do not melt or flow in firing. 4. Light color of Cover-Coat has darker steaks in the final finish. a. The Cover-Coat was applied using a dirty brush. b. The glaze applied could have been applied with a dirty brush. 5. When the piece has been glazed fired, the Cover-Coats look cloudy and sometimes even dull. a. Chances are the clear glaze of choice was applied too heavily. b. The clear glaze could be underfired. c. Check the witness cones for proper firing temperature. d. The piece could be fired one cone hotter and cloudiness might clear up.

8 6. The Cover-Coat when glaze fired feels rough to the touch. a. The piece may be glaze starved and too little glaze was applied. b. The piece could be considerably underfired. 7. The surface of the glazed piece has bubbles and blisters. a. The Cover-Coat firing (bisque firing) was too cool and gas escaped from the ware, thus causing the surface bubbles. b. When this occurs, chances are the Cover-Coat appears lighter in color tone than it should. Underfired Cover-Coats are not true to their color tone. c. The piece could have been fired wet and too fast, thus creating moisture and bubbling. 8. The Cover-Coat color after glazing and firing lifts off the ware in sheets or slivers. a. This is known as shivering, primarily caused by an incompatibility between clay body and color. b. This condition is nonrepairable. c. Can be caused by dirt or hand cream on the ware. 9. When sgraffitoing a piece, the Cover-Coat chips off and does not cut easily. a. The Cover-Coat is too dry and chips when cut. b. The Sgrafitto tool is not held straight up, causing chipping. c. Pulling the tool back into the line instead of pulling from the previously cut line, thus causing the color to chip EZ-Strokes: 1. The EZ Stroke colors are lifting off the ware. a. The colors have been applied too thick and when over-applied lift off the ware. b. Thin color slightly if too thick from the bottle. 2. The EZ Strokes feel grainy below the final glaze surface. a. The EZ Strokes have been applied too heavily. This is true most of the time. b. If glaze is under-applied, the EZ Strokes can feel rough to the touch, especially some of the newer Neon colors and the red family of EZ Strokes. 3. The EZ Strokes have a washed out appearance. a. This will occur when the EZ Strokes are applied too thin or if they have been thinned too much. b. If glaze, especially a Satin Clear, is applied too heavily, this will generate a washed-out appearance. c. Too light of a color has been used over a slightly too dark Cover-Coat. 4. When doing majolica technique (Remember majolica is applying an underglaze type product over a non-moving glaze, i.e., Satin or Envision Glaze), the EZ Strokes applied are rough and grainy in feeling after firing. a. This is caused by too heavy of an application of EZ-Stroke color over the unfired glaze. The color when applied and fired bubbled and could not smooth out. b. Some colors of EZ Stroke do not perform well with majolica techniques. Usually the darker blue family and Sierra Yellow will bubble and blister. 5. When mixing EZ Stroke with French Dimension, how much EZ Stroke can one add to the FD? a. The general rule is to add not more than 50%. b. The color should also be mixed thoroughly with palette knife and slightly thinned. 8

9 6. Occasionally EZ Strokes seem to move in the firing, leaving a shadow or sagging appearance. This is caused by the following: a. Too heavy of an application of glaze. b. Too heavy of an application of EZ Stroke color. c. Too hot of firing. d. Trying to do a Majolica technique over a moving glaze. 7. When making a wash with EZ Strokes, the mix is about 4 parts water to 1 part color and maybe even a little more water. Complete the paper test as described in Essentials 101. However, after doing all of this and after applying the clear glaze and firing, pulls have developed in the glaze. a. This occurs when the wash coat remains too heavy in the creases of a detailed piece. Make a thinner wash and be sure to wipe back as much color as needed to achieve the desired effect. b. Pulling back or crawling will also occur if color is applied too heavily on any piece of greenware or bisque. Mask n Peel 1. When using Mask n Peel, the product does not leave the brush when being cleaned. a. The brush was not conditioned with soap before loading. b. The Mask n Peel dried in the brush when use ended. 2. When using Mask n Peel, sometimes it is difficult to be sure all the mask has been removed. a. Dampen the area next to the removed mask. If the area stays dark, some mask still remains. b. Go back and remove all the mask. If the mask remains through the firing, the color will usually crawl back and any glaze will also crawl. c. Also when applying, be sure to apply the mask heavy enough for easy removal. d. Do not let any color applied over the mask dry thoroughly, especially overnight. 3. There are times Mask n Peel does not dry properly. a. This is usually caused by too heavy of an application. b. Too much soap was left in the brush.

10 Firing Discussion continued: Earthenware to Cone 04 Bisque Earthenware is another term for low-fire ceramics or clay that is bisque fired to cone 04. When this clay body is fired, significant changes take place in the clay body. Bisque firing is the first firing that removes gases and water from the ware. The Dynamics Inside the Kiln During cone 04 bisque firing, minerals in the clay begin to break down and react with other materials to produce gases. At 900º Fahrenheit, red heat water molecules begin to break free from the clay body. With increasing temperature, clay and minerals continue changing form to what will be the final, hard, fairly durable, opaque bisque product. Loading a Kiln for Cone 04 Bisque 1. Place a 1" high false bottom hearth plate in the kiln. This will generate better air circulation in the firing chamber. The slight rise in elevation will also create a hotter firing temperature in the bottom of kiln. 2. Check bottom and shelves of kiln to see that they have been coated with kiln wash. Kiln wash should be completely dry before loading kiln. 3. Use clean shelves and posts, known as kiln furniture. We recommend high-fire kiln furniture; it will last longer and is durable with slightly thicker shelves. 4. Have 03, 04 and 05 shelf cones ready to place on each kiln shelf. Place 04 bar cone in kiln-sitter before loading kiln or set the program on an electronic kiln to shut off at cone Load only bone-dry ware into kiln. Damp ware may crack during firing and sometimes explode, causing damage to other ware in kiln. 6. Greenware pieces and pieces decorated with clay-based underglazes may be placed directly on kiln shelves. Decorated pairs of items should be fired together to ensure like color tone. 7. Undecorated pieces can touch during the bisque firing. For best results, leave ½" to ¾" between individual items and kiln furniture. 8. Keep ware 1" from the kiln wall. Plan your load and arrange it before actually placing it into the kiln; this helps use space efficiently. 9. Items with lids are to be fired with lids on them and ware is to be fired in its normal resting position. 10. When adding another shelf, have ¾" to 1" space between the tallest piece and the underside of the next shelf. Use three posts to support each shelf. 11. Lower shelves into the kiln carefully to avoid damage to the kiln walls or thermocouple, placing shelves so there is a least one element showing between each pair of shelves and one element between the uppermost shelf and the top of the kiln. 12. When kiln is loaded, close lid, set kiln for an earthenware cone 04 bisque fire according to manufacturer s instructions and turn kiln on. 10

11 Additional Bisque-Loading Tips Fire large flat items, in the middle of kiln. Extra-large platters and flat pieces can also be placed on long posts laid parallel on the shelf to form a rack. This helps prevent firing breakage by evenly distributing heat around ware. Stacking items can result in underfired bisque and is not recommended. For best results, be careful not to overload kiln. If overloading occurs, then fire kiln slower and have plenty of ventilation in firing chamber. Unloading Kiln 1. To avoid breakage when unloading a kiln, take ample time to unload carefully. 2. Allow kiln to cool before unloading. Allow kiln to cool slowly, avoiding thermal shock; this is better for ware and elements inside kiln. 3. Make note of cones on each shelf in a firing journal. In the event ware is underfired, it may be necessary to fire ware again. 4. Remove pieces when they can be easily picked up with unprotected hands. 5. Carefully remove shelves and ware carefully, avoiding contact with kiln walls, elements and thermocouple. 6. Stack shelves and posts in an area free from dust and glaze while not in kiln. Cleaning a Kiln 1. To provide the best possible environment for firing earthenware, it is important to clean a kiln regularly. 2. Remove shelves and rewash with kiln wash as needed. 3. Vacuum the inside of kiln weekly or after every 5 or 6 firings. 4. Vacuum immediately if ware blows up in kiln, or kiln brick or kiln wash chips are found inside chamber. 5. When placing hearth plate back in kiln, be sure it is locked in correctly before loading. See you next time in Essentials 103, when we will review and study Duncan Glaze Families. 11