Western Glazes Zinc Free Clear Read more
SKU: WGG4500
$60.00
Series: Western Mid-Fire Art Glazes
Firing Range: Cone 4-5 "Safe" Mid-Fire and Cone 5-6 Mid-Fire
Finish: Clear
Color: Clear
Surface: stiff
Characteristics of Western Glazes | Suggested uses of glaze - Which type to use | Tools for glazing | Before you begin glazing | Glaze application | Reglazing fired ware | Once-Fire glazing | Glazing issues (including crazing & shivering) | Health & Safety
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.
Glaze application
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.
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.
Once-fire glazing
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.
Glazing issues
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 Information
Since 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.
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. With nearly 40 colors of glaze, you can choose from a wide variety of colors and surfaces. All but our two metallics colors are dishwasher, microwave, and oven-proof colors good for functional use. A favorite line by professional and hobbyist artists alike.
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Health and Safety Information
Since 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
