How to use Western Glaze Products
Proper Use Of Glaze
- Characteristics of Western Glazes
- Suggested uses of glaze - Which type to use
- Tools for glazing
- Before you begin glazing
- Glaze application
- Using Underglazes
- Using Engobes
- Reglazing fired ware
- Once-Fire glazing
- Glazing issues (including crazing & shivering)
- Health & Safety
- Transparent Clear Glazes
- Transparent Colored Glazes
- Opaque Gloss-Majolica Glazes
- Art Glazes (lead free)
- Satin-Matt & Matt Glazes
- Crackle Glazes (staining crackles)
- Mid Fire Glazes
- Other Specialty Glazes
- Leaded Glazes
- Glaze Crystals
Characteristics of Western Glazes
Glaze surface qualities vary greatly. Western glazes are grouped into various categories of similar covering quality, reflectivity of light, and surface interest.
There are three characteristics of covering quality: Transparent, Translucent, and Opaque.
Three reflectivity of light characteristics: Gloss(Shiny), Satin-Matt, and Matt
Four categories of surface interest; Crackle, Crystalline, Luster, and Art.
Suggested uses of glaze - Which type to use
Transparent Clear - Great over underglaze or engobe decoration, as well as for use as a liner glaze. Also a good base for which to add coloring stains or oxides.
Transparent Colored - Ideally used over incised designs, translucent glaze colors pool in low areas creating deeper tone of glaze color. Great for baby hand prints, kids projects, decorative or functional ware.
Opaque Gloss (Majolica) - Ideal for dinnerware, vases, and other utility ware as the surface is easy to clean. Use over engobe or underglaze colors when a muted or shadowy design effect is desired.
Satin Matt & Matt - For use on pieces when a glossy surface is not desired (such as flower vases where the container does not compete with the flowers). Good glazes for sculpture or where more realistic surfaces are desired. Good for wax resist techniques, glaze trailing, stippling or spattering as saitn/matt glases are quite stable. Usee 220 Satin Matt over underglaze or engobe when going for a less shiny look.
Art Glazes - Great for decorative ware of all types (vases, boxes, jars, sculpture, tiles) Use on outside surfaces of utility ware as the occasional roughness or textured surface of certain art glazes are not as easy to clean.
Crackle - Use for any style of decorative ware only. (masks, candle holders, sculpture, wall art, ornaments) Not inteded for any ware required to hold liquids.
Tools for glazing
The following are the best tools we have found for use with our products. Although many sustitute or alternate types of tools will work, we recommend the following.
Sponges for cleaning greenware ot bisqueware. We prefer the natural type; Elephant ear or silk. Synthetic will do. One larger sponge for wiping down ware before applying products, and a smaller one for detailed cleanup and touchup.
Brushes. We suggest a good quality flat natural hair brush. A wide brush or fan brush for applying products to large areas or covering with brush-on clear. And a smaller rounded brush for hard to reach places. If necessary to use more than one brush to glaze a piece, the better results you will acheive will justify doing so.
Banding wheel. (or lazy susan) Useful, especially when glazing large items, round bowls or plates. Allows you to spin or turn ware without touching wet glaze!
Ceramic stilts. If you glaze the underside you will want to use a stilt to set your glazed ware on during drying periods, and to use in the kiln to keep glazed bottoms off the kiln shelf.
Before you begin glazing
Good glazing begins with proper bisque firing to secure the degree of porosity which permits the glaze to flow off the brush evenly and smoothly. If the brush drags and the glaze piles up, the bisque is likely to be to porous or underfired. Excessive porosity causes the bisque to absorb too much glaze and bubbling may result. Wetting the bisque down with a clean wet sponge will reduct the porosity and help in getting an even application of glaze. Over-fired bisque is hard and lacks the porosity to permit the bisque to "grip" the glaze and brush evenly. Hard bisque does not absorb water from the glaze, and the glaze will remain wet for a considerable length of time. The correct bisque bisque firing for any given clay depends on the degree of refractoriness of the particular clay. Best results have come from our most popular clay, Low Fire White (LFW) clay from Clay Planet which has a firing range of cone 06 to cone 1. MCP clay from Laguna is also recommended. We recommed a bisque firing of cone 03 or 04 for these clays, and a glaze firing of 05 for low fire glazes.(exceptions to cone 05 are the 900 series reds and oranges. these fire to cone 06) Other clays will work. Including higher fire clays. Test fire these clays to find the best bisque fire cone to achieve proper glaze fit, porosity for brushing glaze, and best color results.
Glazing should begin by wiping the bisque with a wetted and squeezed out sponge to remove any dirt, dust, oils from fingers and such. Dust, grease, lotion, or other debris can cause glaze to lift or crawl during the firing. Use a full brush of glaze at all times. Shake the bottle of glaze thoroughly before use. Open and dip the brush into the glaze and shake it gently, just enough to prevent dripping glaze between the bottle and the ware. Do not scrape the brush on the lip of the bottle, or there will not be enough glaze on the brush to flow freely when applied. Hold the brush against the ware lightly and FLOW the glaze on to the surface in a long continuous stroke. Do not pat the glaze on randomly, especially with the first coat. Smooth the glaze over the ware by brushing back and forth LIGHTLY. Begin the next stroke where the previous stroke ended, and brush back over the area where the two strokes joined. This will smooth out the joint between areas for a more consistent look. Apply the first coat of glaze horizontally, the next coat vertically, as this tends to help hide the look of brush strokes, and helps avoid uneven application. Apply the second, and succeeding coats as soon as the watery sheen has disappeared from the previous coat. Apply as many coats as directed on the bottle of glaze. Some glazes require only two coats for best results (clear glazes), some require more (leaded reds), but most use three coats. Every person is different and every clay is different, therefore some people tend to glaze heavier coats, others lighter. Darker clays you may wish to show the color of through the glaze, and use two coats, some wish to hide the clay color and use three or more coats. For this reason, we strongly suggest doing two or three tests of a particular glaze on a particular clay before glazing an important piece.
Western Lead- Free Underglazes are extremely versatile. They can be used as a translucent one-coat underglaze (for water color effect), or with 3 to 4 coats as a full opaque underglaze.
Application on Greenware - Underglaze should be applied to a well sponged, dust-free dry surface. Use a soft good quality sable or natural hair brush. For translucent effect, load brush with underglaze and apply in one continuous stroke. For over-all solid coverage it is important lay down or scrub in first coat of underglaze to act as a foundation for the subsequent 2 or 3 coats. Each coat should be applies diagonally across the previous coat to hide brush strokes and achieve a more solid color. Bisque fire to Cone 04.
Application on Bisqueware - Application is generally the same as on greenware, but care must be taken that bisques is not too porous/dry as it it will have a tendancy to grab or absorb too much of the water in the underglaze. This can cause it to build up which could then peel or chip off. Due to the porosity of bisque, its recommended to dampen the bisque before decorating with underglaze. Overall best results usually come from using underglazes on application to greenware.
Glaze over any of the underglaze colors with 2 coats any of the clear glazes manufactured by Western (1000, 2000, 3000, 4500, 4545, 220). This will seal and protect the surface. Should you choose to high fire (cone 10) these underglazes, you may see a color shift, especially in a reduction atmosphere. Brighter colors, many of which look great in high fire work best in oxidation or electric firing. We strongly suggest testing before using on valuable pieces at high fire.
Using Engobes (colored slips)
What is an Engobe? Engobe is a white or colored vitreous slip used to improve the appearance of otherwise boring colored clay. Western Engobes are quite versatile and have many uses. They can be applied to anything from leather-hard ware to bisque. The higher fired an engobe is, the more it will form into its own glaze, its surface hardening into a satin at first, then glossing over as the fluxes melt more. Engobes when applied to greenware can be carved through for use in techniques like sgraffito or mishima. Engobes can also be slip-trailed, brushed or sprayed for various effects. When a large area is to be slipped, we suggest application be done at the leather hard state for best adherance. Our Western clear glazes (1000, 2000, 3000, 4500, 4545, 220) can all be used over engobe (2 coats) to show their true brillance in color. (Note: E-119, E-121, E-125 are not recommended for cone 10 due to bubbling.)
Reglazing already fired ware
Sometimes, after the first firing it is apparent that insufficient glaze has been applied. It is possible to apply more glaze and refire the piece. To make the glaze adhere easier to an already glazed piece, we suggest heating the ware in a warm oven (less than 150 degrees F.), and then reglaze. The warm pot will help evaporate some of the water to make it easier to apply more glaze. There are also some products on the market which may help. One is called APT II, ceramic and stoneware enhancer. Follow the directions on the APTII bottle.
With the advent of lead-free low fire glazes, we strongly recommend that you do not use a once-fire process with clay and glaze (apply glaze to greenware and fire only one time). Lead-free glazes have a very narrow firing range. Due to this and the fact that lead-free glazes must be applied to fully matured bisque, it is important, to acheive best results that you do not single fire a ceramic piece with glaze on at the same time. With single-firing you run a much greater risk of pin-holing, crawling, and bubbling. Not to mention the risk of exploding ware from firing damp wares wetted by glaze. If single firing is ever attempted, a protracted extremely SLOW ramp up to temperature is required to avoid the pitfalls of firing by this process, which may likely alter desired glaze results.
If the surface of your ware is rough or dull, not enough glaze was applied, or the ware has been underfired. (or you may have applied underglaze/engobe without or in place of a glaze) Running glaze can be caused by too thick a glaze, or from firing to a higher heat than the chemistry of the glaze will allow, causing it to boil. Bubbling glaze can be caused by numerous reasons, including over-firing, too thick or too many overlapped glazes, improperly fired bisque resulting in an overly porous bisque surface, or firing to quickly. It is also very important that glaze be completely dry before loading and firing in a kiln. Water in a glaze, absorbed by the bisque can boil out causing issues. Each type of clay and glaze has their own expansion and contraction rate. If they are too different problems can result. During cooling, at about 1100 degrees F. the clay and the glaze undergo contraction side by side. Crazing is caused by the glaze contracting more than the clay body on cooling. This means the glaze is stretched tightly over the clay, the glaze cracks to relieve the stress of being stretched resulting in a crazing or crackle pattern. Although there is some evidence that crazed glazes may result in a weaker finished pot, the main concern is aesthetic, and most people just ignore it. Shivering is Of much more concern. In this case the glaze contracts less on cooling than the clay body, putting the glaze under compression. Some compression can be a good thing, resulting in a stronger pot, but too much can cause the glaze to pop or flake off the pot (shivering). In extreme cases this differenc in contraction can cause the pot to split or break (dunting). This might not happen for days or weeks after work comes out of the kiln, so test your clay and glaze compatibility early.
Health and Safety InformationSince 1988 Western Ceramic Supply has been a participating member of the Art and Creative Materials Institute, Inc. (ACMI). All Western ceramic glazes, underglazes and engobes have been evaluated by a toxicologist and are properly labeled for safe use according to the guidelines established by ACMI. Always look for the "AP Non-Toxic" or "CL Caution" seals on all Western Ceramic product labels to insure your safety and awareness as to their proper use in the home, studio, or classroom.
Clear Transparent Gloss Glazes
#1000 - Western Ceramics LEADED Clear Gloss Glaze #1000 is the finest glaze available on the market for use over underglaze colors and engobes. The crystal clear brillance of this glaze brings out the TRUE COLORS of underglaze and engobe. It's wide 11 cone firing range (cone 07 to 4) makes it the favorite of those who work outside the normal firing temperatures. NOTE: 1000 CONTAINS FRITTED LEAD and is not safe for use on food or drink containers.
#2000 - Western Ceramics All-Purpose #2000 LEAD-FREE NON-TOXIC Clear Gloss Glaze works well over underglazes and engobes alike with a firing range of cone 06 to 03, best at 05. A very popular glaze for use by schools and institutions, as it works very well over low-fire earthenware clay bodies. When applying, use only two coats as glaze may cloud if applied too heavily. 2000 is safe for all food and drink containers.
#3000 - Western Ceramics SUPER CLEAR #3000 LEAD-FREE NON-TOXIC Clear Gloss Glaze is a favorite of professionals and hobby potters alike. Specifically formulated to be very clear, with a high gloss surface, it works extremely well over the majority of underglazes and engobes on the market today. Designed to fit low-fire slip casted ware, it is a favorite of slip casting poured ceramic in commercial manufacturing and paint your own pottery shops. Fires from cone 06 to 03. Apply two coats for best results.
#4500 - Western Ceramics Mid Fire Clear Gloss #4500 is LEAD-FREE NON-TOXIC and perfect for the hobby potter. Brush on 2 coats for a solid dishwasher safe fully functional hard coat clear. 4500 can fire from cone 4 to cone 6. Cone 5 is most common. Works very well over Western underglazes and engobes.
Colored Transparent Gloss Glazes
Transparent color glazes are most often used over light/white colored clays. When used on darker or red clays, these transparent colors will show the clay color through the glaze. Engobes can be used this way to enhance or make different color combinations with transparent color glazes. Ideally used over incised designs, translucent glaze colors pool in low areas creating deeper tone of glaze color. Great for baby hand prints, kids projects, decorative or functional ware. Transparent colors also can run a bit more than the opaque glazes, so keep that im mind.
Opaque Gloss/Majolica Glazes
Opaque glazes can be used on dark or light clay bodies, as the colors tend to cover the background on which they are used with only subtle translucent changes from the clay. Because Majolica glazes do have some tendency to flow and equalize an otherwise inadequate application, they are the easiest glaze to recommend for use in schools, especially K thru 6 where beginners and children will most likely use them.
Lead-Free Art Glazes
Western Art Glazes Series (430-444) can give interesting and exceptionally beautiful effects, usually combining gloss and matt textures of varying color all in a single glaze. Texture, shading and overall effect of these glazes vary by the thickness of application, increasing or decreasing of firing temperature, clay body, and length of cooling. Slower cooling can promote the development of more crystal formations, but be careful, this may also cause the glaze to run of applied heavily.
- Art glazes are sensitive to:
Firing Speed - Different results can be achieved by: firing the kiln faster or slower, holding at temperature. We recommend a medium firing speed (4-6 hours) with no hold time.
- Clay Body - Dramatically different results can appear by applying art glazes to different color clay bodies: Whiter bodies will result in brighter colors, darker or red clays can alter the colors dramatically.
- Glaze Thickness - Art glazes are sensitive to the number of coats applied:
1 coat may develop no signifigant patterning
2 coats will develop slight patterning
3 coats develop the BEST patterning
4 or more coats will have a tendency to run, so do at your own risk!
Satin-Matt & Matt Glazes
The soft sheen of the Satin-Matt glazes is the perfect compromise between the flat matt of the matt series and the high gloss of the opaque ot transparent gloss glazes. Colorr range is subdued pastels to deep rich shades.
Matt glazes have a soft dull finish. This type of surface is especially pleasing on large pieces, sculptures, and all kinds of decorative ware. These glazes lend themselves well to sgraffito and wax resist decoration as matt glazes do not flow in firing. Matt glazes are made to brush flat and smoothly, which is very important because matts do not flow in firing like other glazes, and uneven application will be apparent in the finished work.
Low-Fire Crackle Glazes
Crackle glazes are technically "bad" glazes because they do not expand and contract in harmony with the clay to which they are applied. Most glaze is intended to seal the clay to make it water-tight. When a crackle glaze is used, that seal is "cracked" and the ware can leak. This difficulty can sometimes be overcome by using a crackle on the outside only, and a non-crackle on the inside. This usually only works with comparatively thick clay ware.
On thin ware, this cracking can pass through the thin wall and crackle the non-crackle glaze, and in extreme cases, cause very thin walled ware to crack. Obviously, crackle glazes are not dinnerware safe, or good for vases which are to hold water. Use these glazes for DECORATIVE WARE ONLY. A fairly thick application is needed to insure good crackling. The crackling effect starts when the glaze hardens and is nearing the cooling end of the firing cycle, and continues after the ware has been removed from the kiln and can continue for a week or more.
To get the full crackle effect, do not apply stain until the glaze has stopped crackling.
Staining crackle glaze - In most crackle glazes, particularly opaques, the cracks are not readily apparent until they are stained. The stain may be of any colorant such as iron oxide, umber, sienna, colored/india ink etc., mixed with water and brushed or rubbed over the glaze. After the stain is applied, it is wiped off the surface but will remain in the cracks and visually delineate the crackle pattern.
Midfire Cone 5/6 Glazes
Designed for clays maturing at higher temperatures, this glaze series has a range from cone 4 to cone 6 and includes gloss, matt, transparent and opaque glaze types. Firing at a medium speed to cone 5 is recommended for most of these glazes. Only two glazes in this series are leaded. #4535 and #4536. For dry form dipping glazes in the mid-fire series, contact Western for details.
Other Specialty Low Fire Glazes
These categories include Aventurine, and Lava glazes. Aventurine glazes (750 & 751) fire with a silvery copper colored sparkling against a dark, breaking to light background. Three or more coats and a slow cooling develop a great number of sparkles in these two glazes. Lava glazes (797 & 799) produce a crater like effect and can be used in the following ways:
Use alone for a beaded effects
Use over an underglaze for beaded effects
Use over a glaze for a frosty effect
Use underneath a matt or opaque glaze for an alligator lava effect. Swirl or dab this glaze on, no smoothe application is required. Experiment and try your own effects!
Leaded Low Fire Glazes
Western Ceramics in one of the only U.S. glaze manufacturers to manufacture leaded glazes. We have a truly spectacular color line. A bright crystal-clear transparent gloss (#1000), brightly colored TRUE REDS (900 Series), and many amazing specialty art colors in low and mid fire. Lead glazes are not safe for use in schools, and are not food safe! Keep out of reach of children, and use proper safety and cleanup procedures when using these glazes.
Leaded Low Fire Glaze Crystals
Western Glaze crystals contain fritted lead and are not safe for food or drink containers. Sprinkle glaze crystals on wet low fire glaze when you apply your final glaze coat, or mix crystals into your glaze when brushing on for speckled coloring effects. Fire to cone 05 / 06.
Crystals sold in 4 ounce containers, $8.00 for Red, Orange, & Yellow. $6.00 for Dark Green, Medium Green, Dark Blue, Brown, Black, White, & Amber.