Ceramic Glaze/ Amaco Glazes   Ceramic Glaze/ Amaco Glazes The Basics

Three Basic Elements in Glaze: Silica-A hard, unreactive, colorless compound that occurs as the mineral quartz and as a principal constituent of sandstone and other rocks. Flux-The action or process of flowing or flowing out. Alumina-A white solid,aluminum oxide,that occurs in bauxite and is found in crystalline form as the main constituent of corundum, sapphire, and other minerals.

Coloring Agents: Cobalt-A chemical element of atomic number 27, a hard silvery-white magnetic metal. Copper-A red-brown metal, the chemical element of atomic number 29. Maganese-the chemical element of atomic number 25, a hard gray metal of the transition series. Iron-a strong, hard magnetic silvery-gray metal, the chemical element of atomic number 26.

Glossy Vs. Mat/Waxy Glazes -Glossy galzes look best on small projects. They tend to hide the form. -Larger forms need less sparkle to attract attention therefore matte glazes look better.

What's the difference between glaze and underglaze? Glaze is a blend of powdered chemicals and minerals mixed with water and applied to clay. When fired to the glaze's maturation temperature it melts and becomes a thin layer of colored glass that fuses to the clay and acts as a decorative and utilitarian surface on the clay.  Underglaze as conveyed in its name is a similar blending of minerals as in glaze with the addition of clay and other less melting components along with a greater content of color producing chemicals that allow the user to do more detailed decoration on the clay surface before applying a usually desired protective layer of glaze on top of the underglaze. Separate firings of underglaze and glaze is NOT always necessary but may be advantageous in extremely detailed underglazing applications.  See Underglazes See Glazes

What is engobe?  Engobe is an American term for decorative slips used for simple and basic color decoration. They are essentially the least complex formulas of the underglaze family. Because of there simplicity they are generally required to be applied to either semidry or leatherhard clay. The higher clay content in engobes often limits the color selection to basic shades that oxides provide.  See Engobes

Glazing & Applications Glaze is shiny and wet when first applied, then becomes matte as the bisque absorbs the water. If you recoat too soon over a damp coat, you’ll move the foundation layer rather than imparting a second coat. Which will make things look streaky and unevenly covered.

Why Does the Surface Feel Rough? Glaze applied too thinly or not fired high enough, usually occurs with a matte or waxy glaze.

Glaze Defects Defects in compounding the glaze Improper firing Poor application

Peanut Butter Theory Heavy particles fall to the bottom and will not be in your flaze application unless you heavily shake and stir up the glaze.

Bubbles Q: Why did I get bubbles in my glaze? Bubbling in glaze can arise for several reasons. The first can be caused by physical air that was trapped during application and not allowed to escape in the glaze firing because the firing was too fast or not fired hot enough. A glaze application that is not thick enough can also cause bubbling. During firing, air bubbles form in glaze, but they usually “heal” themselves during the rest of the firing. A healed bubble is not considered an irregularity. However, sometimes the burst air bubble doesnt heal, Due to the thickness of the glaze, it is not unusual for bubbles to form on the interior bottom of our pots.

Blisters Q: Why did I get blisters in my glaze? Blistering in glaze is most often attributed to over firing and or too thin of a glaze application. It can be the result of a firing that has been completed and the retained ambient heat provides additional boiling or out-gassing of the glaze while the local air is already cooling the glaze on the surface. 

Pinholes Q: Why did I get pinholes in my glaze? Pinholing results in glaze from bubbling or blistering that was not allowed to settle down in the glaze firing cycle. Corrective steps that can be taken include multiple thinner glaze applications rather than one thick single application, avoid over-firing, and applying a heat soaking procedure at the melting high end of the firing can help allow any remaining gas to escape before hardening upon cool down. Possible causes: too fast of a firing cycle Too fast of a cool down Too thick of an application of glaze

Crawling Caused by: Dust on pot not being removed Oil from hands Too thick or uneven of a glaze application Wet glaze applied over a completely dry coating,or an unclean, undampened, or oily surface.

Crazing Caused By: Glaze shrinks more than the clay during the firing Usually happens with glossy glaze

Dunting Caused By: Cracking of ware due to stress Not always a glaze defect Poor construction to improper firing and cooling Stress can occur if the difference between the inside glaze and the outside glaze is too great

Peeling Caused by slips applied to clay that are too dry or have already been bisqued and the slip shrinks more than the pot so it peels off taking the glaze with it

Running Caused by: Glossy glazes applied too thickly will run off the pot

Shivering The most problematic of glaze defects, particu;ar;y in any functional ware, since silvers of glaze from edges can drop into food or drink. These silvers are usually small, sharp, jagged- edged pieces that detach themselves from the body. It is the most dangerous of glaze faults. Caused by glaze not shrinking enough to fit the pot will flake off while cooling, especially along edges and corners

Amaco Glazes Liquid Gloss- Gloss Glazes fire to a smooth, glossy finish at a witness Cone 05. Always slow fire lead free glazes for best results. Gloss Glazes flow slightly during firing to a high gloss finish, while correcting most application imperfections. Liquid Matte- The AMACO Low Fire Matt glaze series is a group of satin-matt glazes that boast a bright, lively color palette and a buttery soft surface after firing. Unlike more fluid glazes, these glazes are stiff and will not flow in the kiln, making them perfect for certain types of decorative techniques and surface treatment for both pottery and sculptural ware.

Continuation: F-series- (F) LEAD FREE glazes were created in 1950 as America's first all Lead Free glaze series . They are semi-opaque and fire with a high gloss. Colors are more intense and brilliant than those of many other glazes. Crystaltex-Amaco Crystaltex liquid glazes are a brilliant mix of bright, glossy colors that are speckled with colored glaze crystal bursts. These glazes are perfect for unique ceramic vessels and dishes, and could be perfect for an interesting surface for sculptural ceramic work. All the unique beauty of crystalline glazes without the complicated firing process.

Continuation Opalescent-Although Opalescent Glazes may be used on any clay, they develop their greatest opalescence and most interesting textures when applied over red burning AMACO Sedona Red Clay No. 67. The Opalescent Glazes have a high gloss finish when fired. Best results are achieved with three or four applications of glaze. On textured ware, the glaze flows thin on relief and thick in incised areas, giving an added dimension on the surface. Texture Aligator-No two pieces glazed with AMACO Textured Alligator Glazes are ever alike due to the many variations in texture which occur in firing.

Glaze Pictures