Does Ceramic Glaze Wear Off?

What is ceramic glaze?

Ceramic glaze is a glassy coating applied to ceramic wares like pottery, porcelain, and tiles (Ceramic glaze Definition & Meaning, 2022). It is made by combining and melting various powdered minerals, chemicals, and pre-smelted glass materials into a liquid slip that can be applied to biscuit fired ceramics before a final firing (Ceramic glaze, 2023).

Glazes serve several purposes in ceramic wares. They provide a protective glossy or matte coating that makes the ceramic impervious to liquids. Glazes also enhance the appearance of ceramics with colors, patterns, and textures. The glaze melts and fuses to the ceramic body during firing, sealing pores and strengthening the piece. Proper glazing improves durability and can make ceramics suitable for utilitarian objects like tableware, bathtubs, and floor tiles (What is A Ceramic Glaze?, 2023).

How is ceramic glazed?

Glazing is the process of applying a vitreous (glass-like) coating onto the surface of pottery. There are several techniques used to apply glaze to bisqueware (unglazed, fired clay) before the final firing:

Dipping involves fully submerging the bisqueware piece into a container filled with glaze. The piece is dipped in vertically and then removed slowly to allow excess glaze to drip off. Dipping results in an even, all-over application of glaze.

Glaze can also be applied by pouring it directly onto the surface of the bisqueware. Tilting and rotating the piece allows the glaze to flow evenly over all sides. Pouring gives the artist more control over glaze thickness and coverage.

Spraying glaze through an airbrush or spray gun is another technique. The bisqueware is held several inches away from the spray nozzle and lacquered in thin, overlapping layers. Spraying produces uniform glaze layers, allowing for detailed effects.

Glazes can also be painted onto bisqueware using brushes, sponges, or other tools. This gives the most control for decorative techniques like detailing, textures, or blending multiple glazes.

Can ceramic glaze wear off?

Yes, ceramic glaze can wear off over time, especially on frequently handled items like mugs, plates, and bowls that are subject to repeated washing and contact [1]. Glaze provides a protective coating for the clay body beneath, so as it wears thin, the unglazed clay becomes exposed and more vulnerable to staining, moisture absorption, and bacterial growth. The glaze can chip, crack, or fade with regular use. However, quality glazes applied at proper thickness, fired at high enough temperatures, and cared for properly can remain intact for many years of normal household use.

Reasons glaze wears off

There are several reasons why ceramic glaze can start to wear off over time:

Friction

Friction from daily use is one of the main causes of glaze wear. Items like plates, bowls, and mugs are constantly subject to abrasion from utensils, foods, and cleaning which slowly erodes the glaze over time. According to experts at Ceramic Arts Network, thinner glazes and those with fine buff clay particles are more prone to friction wear (Source: https://ceramicartsnetwork.org/daily/article/How-to-Correct-Five-Common-Ceramic-Glaze-Defects). Using a soft sponge or cloth when cleaning glazed pieces can help minimize friction damage.

Impact

Dropping glazed ceramic can chip, crack, or scratch the glaze leaving exposed clay underneath. Ceramics with thicker, high-fire glazes tend to resist impact damage better than thinner glazes according to potters on the Ceramic Arts Daily forums (Source: https://community.ceramicartsdaily.org/topic/7792-does-fading-always-mean-a-glaze-isnt-food-safe/).

Thermal shock

Exposing glazed ceramic to sudden temperature changes can cause cracking or crazing in the glaze, exposing the clay body. Going from very hot to cold too quickly, like rinsing a hot bowl with cold water, is a common cause of thermal shock. Low-fire glazes are generally more susceptible according to Quora users (Source: https://www.quora.com/How-much-longer-can-I-use-ceramic-dishes-that-have-their-glaze-starting-to-wear-down). Letting items cool gradually can help prevent thermal shock.

Crazing

Crazing refers to the fine crackling that can develop in glazes over time with use and aging. It occurs when the glaze and clay body expand and contract at different rates. Crazing creates weaknesses in the glaze that can lead to chipping, scratching, and wearing. Proper clay preparation and glaze compatibility minimize crazing.

Ways to Prevent Glaze Wear

There are a few key ways to help prevent glaze wear on ceramic pieces:

Proper firing is essential for creating durable glaze that resists wear and tear. Glazes should be fired to the temperature recommended by the manufacturer, as underfiring can result in a glaze that is not fully matured and prone to chipping or scratching. Slow cooling the kiln once firing is complete also allows glazes to fully fuse to the clay body for added strength.

Applying an adequate thickness of glaze is also important. Thin or uneven glaze coverage can lead to exposed areas that lack protection. Using the right brush size for the piece and applying 2-3 coats to bisqueware helps ensure complete coverage.

Lastly, gently handling glazed ceramics helps maintain the glaze surface. Avoiding sharp objects that can scratch and being cautious not to chip edges or rims will help preserve glaze integrity. Glazed pieces should be stored securely and stacked carefully.

Fixing worn glaze

If the glaze on your ceramic item is worn down in spots, there are a few ways to fix it. The most thorough option is to reglaze the item by applying a new layer of glaze and firing it in a kiln again. This takes skill and access to a kiln, so it’s best left to professional ceramic studios. For DIY touch ups at home, there are products like Porcelain Restoration Glaze and ceramic glaze repair pens. These products can be painted onto worn areas and don’t require firing. The results won’t be quite as smooth and uniform as a professional reglazing, but can mask chips and flaws. Another simple fix is to apply small self-adhesive felt pads to the underside of ceramic items in high-wear areas. This prevents the glaze from directly contacting the surface it sits on, protecting it from abrasion over time.

Ceramic items prone to wear

Certain types of ceramic items are more prone to glaze wear over time and usage. Three commonly used ceramic products that often experience glaze wear are tableware, cookware, and floor tiles.

Tableware such as plates, bowls, and mugs used daily can start to show glaze wear over time, especially on areas that come in frequent contact with utensils. The glaze on the bottom of mugs or cups is also prone to wearing down from repeated contact with hard surfaces (Source).

Cookware like pots, pans, and baking dishes are subject to glaze wear from constant abrasion and exposure to heat. Areas exposed to direct flame or heating elements often exhibit glaze wear first. The insides of cookware can also wear from repeated use of cooking utensils and cleaning (Source).

Ceramic floor tiles frequently show glaze wear over time, especially in high traffic areas. The tiles can gradually lose their protective glaze coating from frequent walking, dropping of objects, moving furniture, and mopping or scrubbing.

Glaze Types and Wear Resistance

The type of ceramic glaze used can significantly impact its durability and resistance to wear. Glazes fall into main categories based on the type of clay body they are fired onto: earthenware, stoneware, and porcelain. The higher temperature at which stoneware and porcelain are fired results in a more durable ceramic material and glaze.

Earthenware glazes are applied to low-fire clay bodies like terracotta. They melt at lower temperatures, typically around 1800°F – 2000°F. While often vibrant in color, earthenware glazes are the least durable option. They can chip, fade, and wear down more easily with regular use. Earthenware glazes are best for decorative or gently-used items.

Stoneware glazes are fired at higher temperatures around 2200°F – 2400°F onto stoneware clay bodies, resulting in increased durability. The glazes vitrify and fuse to the clay at these temperatures. Stoneware glazes hold up well to repeated use and exposure to heat, moisture, and acids. Popular for tableware and cookware, quality stoneware glazes become less porous and prone to scratching or staining.

Porcelain glazes fired at the highest temperatures above 2300°F producethe most durable ceramic wares. The very high heat vitrifies the glaze fully, creating an impervious glass surface that is highly chip and stain resistant. Porcelain tableware, cookware, and sanitaryware maintain their glossy surfaces over decades of heavy use. The hardness and durability of porcelain glazes make them ideal for commercial applications.

Caring for glazed ceramics

To get the longest life out of glazed ceramics, gentle use and handwashing are recommended. The glaze on ceramics is durable but can chip or wear down over time with improper care.

Avoid abrasive scouring pads or harsh dishwasher detergents when cleaning glazed ceramics, as they can damage the glaze over time. Instead, hand wash items with a soft sponge or cloth and a mild liquid dish soap. Be gentle when scrubbing to avoid scratching the glaze.

Proper storage is also important for glaze preservation. Avoid stacking glazed ceramics directly on top of one another, as this can cause chipping or abrasion. Store ceramics on shelves lined with felt or cloth instead. Maintaining consistent temperature and humidity is ideal, such as around 50% relative humidity. Fluctuating conditions can accelerate glaze damage over time. As noted by the Canadian Conservation Institute, “Store unstable glass, particularly if it is prone to weeping or crizzling, in an environment that maintains a stable RH between 40-50%.” (Source)

With proper gentle care and storage, glazed ceramics can last for many years while still looking beautiful.

When to accept natural wear

Glaze wear can add antique character over time. As ceramic pieces are used and washed over many years, it’s natural for the glaze to slowly erode. This reveals more of the underlying clay body, creating a worn, vintage look. Many ceramic artists and collectors actually prize and accentuate this kind of wear as an appealing patina that comes with age. As Maria Martinez, the renowned Native American potter from San Ildefonso Pueblo said, “Beauty lies in the imperfections.”

Rather than fight natural glaze erosion, it’s often best to accept some wear as part of the life story of heavily used ceramic items like mugs, plates, and bowls. This reveals the origins of the piece in natural clay. As long as the glaze wear isn’t excessive or causing functional issues like increased staining or porosity, controlled wear can add character. Pieces that acquire a worn, antique look are said to have “sabi” in Japanese aesthetics – appreciating natural imperfections. Some ceramicists even distress glazes intentionally during the firing process to imitate the effects of age and use.

It’s often worth the effort to repair badly worn glaze, especially on special handmade ceramic pieces that may have sentimental value. But for many everyday dishes that get frequent use, accepting natural glaze wear can add to their beauty and story over a lifetime of meals shared.

Source: https://potterycrafters.com/what-to-wear-when-doing-pottery/