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Glaze Leaching Test - GLLE

This test procedure was employed in the Foresight Ceramic Database and now is available for those having an account at Insight-Live.com. Accumulating test data using the variables defined in these procedures enables us to create tools that enable you to compare the physical properties of materials and recipes.


All glass leaches to some extent when it comes into contact with water (or acids and bases), especially if the contact occurs over a period of time or the liquid is hot. This is evident by a change in the gloss and/or texture of the glass surface over time. Glazes can pass a test of acid attack (e.g. lemon juice) yet fail the attack of bases (e.g. detergents). These simple tests can be done by anyone. After each dry the specimens and compare the non-leached and leached surfaces for difference in color and gloss.

Vinegar Test: Fill a glazed container half full of vinegar and leave it for several days. If the vinegar turns yellow, this is an indication of lead release.

Dishwasher Test: Take two identical items and put one in your cupboard and leave one in the dishwasher for two months.

Soda Ash Test: Mix 50 grams of soda ash to one liter of water, bring to a boil in a stainless steel pan, simmer glazed specimens for 6 hrs checking every half hour to add more water.

Lemon Slice Test: Lemon juice is more acidic than water (actually it is even more acidic than vinegar). Place a lemon slice against a glazed surface and leave it in contact for several days. Make sure that it is in close contact with the surface and stays wet (put plastic wrap over it to keep it from drying out and a weight on top if needed). Look for differences in surface color, texture or character.


VNGR - Vinegar (V)

Note any differences surface color, texture or character.

DWSH - Dishwasher (V)

Note any differences surface color, texture or character.

SODA - Soda Ash (V)

Note any differences surface color, texture or character.

LEMO - Lemon Slice (V)

Note any differences surface color, texture or character.

Lemon Leaching Test on a Copper-containing Glaze

Lemon Leaching Test on a Copper-containing Glaze

This was left for 24 hours. Wrapped in stretch wrap. Then the surface of the glaze was inspected under a lamp to detect any differences between the lemoned and non-lemoned surfaces. Lemons are highly acidic. This glaze passed because the base recipe, G3806N, was methodically developed so that it has plenty of Al2O3 and SiO2 (in the fired chemistry) to build a stable glass.

Out Bound Links

In Bound Links

  • (Tests) GLFL - Glaze Melt Flow - Runway Test
  • (Articles) Concentrate on One Good Glaze

    It is better to understand and have control of one good base glaze than be at the mercy of dozens of imported recipes that do not work. There is a lot more to being a good glaze than fired appearance.

  • (Oxides) CuO - Cupric Oxide
  • (Glossary) Food Safe

    In recent years potters and small manufacturers have become aware (or have been forced to become aware) that ceramics and pottery are not as inert as they once thought. A variety of potential health impacts exist to users of ware they make. These include flaking off of glaze chips (that could be ing...

  • (Glossary) Glaze Durability

    Ceramic glazes vary widely in their resistance to wear (cutlery marking, scratching) and leaching by acids and bases. The principle factors that determine durability are the glaze chemistry and firing temperature. In industry technicians are accustomed to evaluating glazes by looking at their oxide ...

By Tony Hansen

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