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Glazing

Glazing. Glaze- glass like minerals, clay and water. A thin coat is applied to bisqueware . After firing, it is permanently bonded to ceramics. Why Glaze?. Seals your pottery-Otherwise leaky and bacteria can grow in it, hard to clean, frozen water can make ceramics crack.

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Glazing

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  1. Glazing Glaze- glass like minerals, clay and water. A thin coat is applied to bisqueware. After firing, it is permanently bonded to ceramics.

  2. Why Glaze? • Seals your pottery-Otherwise leaky and bacteria can grow in it, hard to clean, frozen water can make ceramics crack. • Decorates- many different colors and effects • Makes ceramics stronger

  3. Selecting a Glaze • Glazes change colors when fired – Must look at sample chips to know outcome! • Opaque or Transparent? (know the meaning) • Matte or Gloss? (know the meaning) • Could your piece be used for food or drink? Look for this fork and knife symbol . It means it will be safe after firing to eat or drink out of, so it is a “food safe” glaze. • Codes on jar: LG, LM, O, CTL, TP, LT, A- know what they mean!

  4. Other Symbols on Jar AP- (Approved Product) Non Toxic- Safest to use. This does not mean that you will not get sick if you eat it!! CL (Caution Label) Must be in 7th grade or older to use. Contains chemicals that are dangerous to ingest (swallow), inhale, or have on your skin for a long time. Follow guidelines for safety.

  5. Even in “Food Safe” glazes… Even food-safe or Glazes are dangerous when inhaled, ingested, or on skin. Long time exposure can cause cancer, liver damage, damages developing fetuses. (in liquid, unfired form)

  6. Lead Poisoning • Causes Brain Damage in peopleand developing fetuses. • Look for “Lead Free” on the jar. Most should have it. • PWHS tries not to buy glazes with lead, but keep an eye out, we might have some for special applications. • Another reason to read the label!

  7. Safety Guidelines: • . Glaze on newspaper.(easier to throw out, than to clean) DO NOT glaze on bare table, boards or cloth. • DO NOT create glaze Dust: • Do not flake off dry drips of glaze. Wipe tables well after glazing with a wet rag. • No Eating, Drinking, Gum chewing, or putting fingers in/near your mouth when glazes are being used in the room. • Wash hands well. Use care.

  8. How to glaze at PWHS: • Select color- look at sample chips • Use soft brush(dark bristles better) • Dip directly into glaze jar- never pour into cap or another container. Why? • Makes cap hard to close/open-then glaze dries. • Wastes expensive glaze • More to clean up • Keep track of lid- don’t mix up • Never mix wet glazes, Use clean brush.

  9. Three Coats of Glaze • Each coat must dry between coats (5-10 minutes). Will look caulky when dry • Go in different directions for each layer • Never glaze on the bottom of a pot. Leave 1/8” unglazed at bottom edge . • Otherwise it will stick to the kiln shelf / Drip onto the kiln self.

  10. Getting Started: Prevent Crawling • Wipe or rinse out bisqueware to remove all dust. Yes you can put it in water, but then it has to dry. • Nooil on surface -Make sure no greesy fingerprints are on bisquware • No lotion before touching • Wash hands after lunch/eating chips, etc. Grease will keep glaze from sticking. Consistancy-should be the thickness of latex paint, drinkable yogurt, or heavy cream. Mix with fork. See your teacher before adding water.

  11. Crawling The separation of a glaze coating from the clay body during the firing caused by excessive coats of glaze, or dust /oil on the bisqueware. This results in exposed areas of unglazed or bare clay.

  12. Crazing • Undesirable cracks in the glaze. Caused by excessive coats of glaze or cooling too fast . Keep track of how many coats are applied where. –You or your teacher cannot tell by looking at it later. Write it in your notebook!

  13. Common Mistakes: • Make sure all areas covered with 3 coats. Overlap areas where glaze colors change a little (common mistake – thin or bare spots where colors change) • 1-2 coats= streaky, light colors, not shinny, not fully sealed.

  14. Pour and Roll Technique • Used for inside of a large pot/vessel only. • Clear glaze often used- especially if area is not seen. • Get helpthe first time. 1. Pour in 1-2 cups of glaze (liquidy, not lumpy) 2. Twist and roll around 3. Roll as you slowly pour out (back into glaze jar so you do not waste it) 4. Once is enough, 3 coats not necessary.

  15. Acyrlic Paint and Wax technique • Large Vessels • Always an option • Must earn “C”or better for privilege to glaze.

  16. Layering glaze

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