[caption id="attachment_16851" align="alignright" width="300"]<a href="https://staging.ceramic.school/wp-content/uploads/2017/10/The-ancient-town-Green-glazed-ceramics.jpg"><img class="size-medium wp-image-16851" src="https://staging.ceramic.school/wp-content/uploads/2017/10/The-ancient-town-Green-glazed-ceramics-300x200.jpg" alt="green-glazed ceramics" width="300" height="200" /></a> <em>The Ancient Town Green-glazed Ceramics</em>[/caption]
<p style="text-align: justify;">Glaze is a substance that is fused to ceramics through firing in a kiln to a certain temperature.</p>
<p style="text-align: justify;">In its most simplest term: Glaze is the outer layer on a pot or a mug,that makes it waterproof,glossy,and gives it color. You can think of glaze like a coating of liquid that surrounds the clay and turns to a hard glass like substance when fired in a kiln. Although glazes can look and feel very different. Glazes are typically made in powder form,and then made into a liquid to coat the pot. Glaze dries on the ceramics,and fuses to it when it is placed in a kiln and fired to a certain temperature.</p>
<p style="text-align: justify;">Glaze:</p>

<ul style="text-align: justify;">
 	<li>is made up of three main materials,</li>
 	<li>it can be fired to different temperatures,</li>
 	<li>and appear in many different colors and textures.</li>
</ul>
<p style="text-align: justify;">In this article,we will be discussing what is a glaze,how glaze is made,what materials make up glaze,the colors and textures that can be created through glazing,and the different temperatures that it can be fired to.</p>

<h2>What is Glaze Made out of?</h2>
<p style="text-align: justify;">Glaze is made up of three primary materials,and can also include additives in order to achieve certain colors or levels of opaqueness.</p>
The three primary materials that every glaze should contain are:
<ol>
 	<li>a glassformer,</li>
 	<li>a refractory</li>
 	<li>and a flux.</li>
</ol>
<h3>What is a glassformer?</h3>
<p style="text-align: justify;">A glass former is a material that will become glass once it has been fired. Silica is the most common glassformer used and can be found in quartz,flint,and pure silica. Every glaze needs a glassformer or it will not be successful.</p>

<h3>What is a refractory?</h3>
<p style="text-align: justify;">A refractory is any material with a high melting point. The reason for this is that it will stiffen the glaze and prevent it from sliding off of the clay when it is fired. Alumina is the main refractory found in glazes and can be found in clays. Some clays include kaolin,ball clay,fire clay,or even just alumina hydrate.</p>

<h3>What is a flux?</h3>
<p style="text-align: justify;">Fluxes are used to lower the melting point of the glassformer so that it will melt in the kiln. Without the fluxes,the glassformer will need a much higher temperature than what is attainable in a kiln in order to have the same results. Some examples of fluxes include feldspar,whiting,calcium carbonate,dolomite,barium carbonate,zinc oxide,gerstley borate,feldspars,and lead. It is important to note that some of these materials can be toxic such as <a id="amznPsBmLink_2132980" class="amzn_ps_bm_tl" href="http://www.amazon.com/Zinc-Oxide-Ceramic-temperature-UnCalcined/dp/B01F1SUGGI/ref=as_li_bk_tl/?tag=ceramicschool-20&amp;linkId=850492714e91b4a33f6a432bc5e30e64&amp;linkCode=ktl" target="_blank" rel="nofollow noopener noreferrer" data-amzn-ps-bm-keyword="flux for pottery" data-amzn-link-id="850492714e91b4a33f6a432bc5e30e64">zinc oxide</a><img id="amznPsBmPixel_2132980" style="border: none !important; margin: 0px !important; padding: 0px !important; height: 0px !important; width: 0px !important;" src="https://ir-na.amazon-adsystem.com/e/ir?source=bk&amp;t=ceramicschool-20&amp;bm-id=default&amp;l=ktl&amp;linkId=850492714e91b4a33f6a432bc5e30e64&amp;_cb=1506915375605" alt="" width="0" height="0" border="0" /> and lead. Do not put them on functional work and be extremely careful when handling them.</p>

<h2>What else can you add to a Glaze?</h2>
<p style="text-align: justify;">Other additives that can be added to a glaze include opacifiers,suspenders,and colorants. These are what will give your glazes color,suspension,and opaqueness.</p>

<h3>Opacifiers</h3>
<p style="text-align: justify;">Opacifiers help change the glaze from transparent to opaque. Some of the materials that can be used include tin oxide,zirconium or zircopax,titanium,and zinc.</p>

<h3>Suspenders</h3>
<p style="text-align: justify;">Depending on what you add into your glaze certain materials will naturally gravitate towards the bottom while others float to the top. To help prevent the glaze from settling back down you can add materials that will keep it in suspension,which is important for a good glaze coating. The main suspension agent is bentonite,but there are also alternatives such as CMC or Magma which are gum suspensions.</p>

<h3>Colorants</h3>
[caption id="attachment_16850" align="alignright" width="300"]<a href="https://staging.ceramic.school/wp-content/uploads/2017/10/Colors-You-Can-Put-In-a-Glaze-e1506916224307.jpg"><img class="size-medium wp-image-16850" src="https://staging.ceramic.school/wp-content/uploads/2017/10/Colors-You-Can-Put-In-a-Glaze-300x294.jpg" alt="glaze" width="300" height="294" /></a> <em>Some of the Colors You Can Put In a Glaze</em>[/caption]
<p style="text-align: justify;">Colorants are what allow you to change the color of your glaze. They are mainly oxides or carbonates that will provide various colors depending on the firing temperature,atmosphere,and other characteristics of the firing. Some examples of colorants include cobalt oxide,copper oxide,copper carbonate,cobalt carbonate,chrome oxide,red iron oxide,and so on.</p>

<h2>What Colors can you put in a Glaze?</h2>
<h3>Cobalt</h3>
<strong>Forms:</strong> Carbonate or Oxide

<strong>Color:</strong> Blues,color will darken or lighten depending on percentage of colorant
<h3>Copper</h3>
<strong>Forms:</strong> Carbonate or Oxide

<strong>Color:</strong> Greens,turquoises,and copper reds
<h3>Chrome</h3>
<strong>Forms:</strong> Oxide

<strong>Color:</strong> Greens mainly
<h3>Red Iron</h3>
<strong>Forms:</strong> Oxide

<strong>Color:</strong> Red earthy brown
<h3>Iron</h3>
<strong>Forms:</strong> Oxide

<strong>Color:</strong> Reddish brown
<h3>Magnetite</h3>
<strong>Forms:</strong> Mineral form of black iron oxide

<strong>Color:</strong> speckling effect
<h3>Manganese</h3>
<strong>Forms:</strong> Carbonate

<strong>Colors:</strong> Red,brown,purple,purple brown,blue purple or black tones
<h3>Nickle</h3>
<strong>Forms:</strong> Carbonate or Oxide

<strong>Colors:</strong> Browns,blues,grays,and yellows
<h3>Rutile</h3>
<strong>Forms:</strong> Granular or powdered (light or dark)

<strong>Colors:</strong> Speckling,tan,grey brown to dark brown
<p style="text-align: justify;">These colorants,which can produce beautiful colors all on their own,can create even more variations when you combine them with each other. Depending on what other materials are in the glaze,such as a specific flux<img id="amznPsBmPixel_4610716" style="border: none !important; margin: 0px !important; padding: 0px !important; height: 0px !important; width: 0px !important;" src="https://ir-na.amazon-adsystem.com/e/ir?source=bk&amp;t=ceramicschool-20&amp;bm-id=default&amp;l=ktl&amp;linkId=f86e43c7cad00758de46c4e581b41a12&amp;_cb=1506915258510" alt="" width="0" height="0" border="0" />,the glaze can be affected to an even greater degree. This allows for variation in glazes that is great for experimentation and creating a unique glaze to call your own. <a href="https://staging.ceramic.school/how-to-read-a-glaze-recipe/">How to read Glaze Recipes</a>. You can even add commercial mason stains to your glaze to change the colors as well. A good example is creating a pastel pink or a light purple using a white glaze and then adding in however much purple or pink mason stain you desire to create the perfect shade.</p>

<h2>Textures in Glaze</h2>
<h3>Glossy</h3>
<p style="text-align: justify;">Glossy is when the glaze is reflective glass and can be hard to photograph since light will be reflected off of it. This is what glazes are typically like and especially are for liners inside of functional ware.</p>

<h3>Matte</h3>
<p style="text-align: justify;">Matte is when the glaze has no shine and will absorb the light that is placed on it. Matte work is very easy to photograph. The feeling of touching matte glazes can compare to touching stones or satin depending on the composition of the glaze.</p>

<h3>Non-Food Safe Textures</h3>
<p style="text-align: justify;">While these are technically glaze faults and occur when something is wrong with the glaze,it can have a purpose to add interesting variations to non-functional work.</p>

<h3>Crazing</h3>
<p style="text-align: justify;">A series of fine cracks that appear over the entire glazed form is called crazing. This usually occurs when there is a mismatch between the clay body and glaze.</p>

<h3>Crawl</h3>
<p style="text-align: justify;">A series of islands of glaze with bare clay between them is called crawling. This occurs when there is an excess of plastic clay content or if glazes are applied too thickly or in multiple layers.</p>

<h2>Levels of Opaqueness with Glazes</h2>
<h3>Opaque</h3>
<p style="text-align: justify;">Opaque refers to glazes that are solid colors and cannot be seen through at all. The clay body is not visible through the glaze at all.</p>

<h3>Semi-Opaque</h3>
<p style="text-align: justify;">Semi-opaque refers to glazes that are mostly solid colors and have a slight visibility through it. The clay body can be glimpsed through the glaze.</p>

<h3>Semi-Transparent</h3>
<p style="text-align: justify;">Semi-transparent refers to glazes that are translucent colors and can be seen through somewhat. They are not completely transparent,but the clay body can be seen through the glaze to give the glaze a lighter or darker tint depending on the body color.</p>

<h3>Transparent</h3>
<p style="text-align: justify;">Transparent refers to glazes that are translucent colors and can be very see through. The clay body can very clearly be seen through the glaze and will make the glaze lighter or darker depending on the body.</p>

<h2>Extra Terms to Know</h2>
<h3>Breaking</h3>
<p style="text-align: justify;">Breaking refers to glazes that will change color and transparency as it thins or thickens on areas that are raised up or recessed during the firing. While some glazes will only change shades slightly with breaking,there are others that will change drastically when breaking and create a whole new color.</p>

<h3>Flowing</h3>
<p style="text-align: justify;">Flowing refers to glazes that will run and bleed when fired. These glazes can and will run into other glazes and can even run off the form altogether.</p>

<h3>Stiff</h3>
<p style="text-align: justify;">Stiff refers to glazes that will stay put and not budge when fired. These glazes tend to be matte glazes,but depending on the composition of the glaze can also be glossy glazes.</p>

<h2>Temperatures for Glazes</h2>
<p style="text-align: justify;">Glazes can be used in all different types of firings. Some firings require specific formulas to ensure success in the firing,while others may not. The different firing temperatures range from lower mid-range,mid-range,and high fire.</p>

<ul style="text-align: justify;">
 	<li>Lower mid-range focuses on low fire clays,which is earthenware,and the glaze for this range varies from cone 01 (2079 F/110C).</li>
 	<li>Mid-range focuses on some stoneware clays that will vitrify at this stage,and the glaze for this range varies from cone 4 (2167F/1165C) to cone 7 (2264F/1210C).</li>
 	<li>High fire focuses on stoneware and porcelains that will vitrify at this stage,and the glaze for this range varies from cone 8 (2305F/1260C) to cone 10 (2381F/1305C).</li>
</ul>
<p style="text-align: justify;">On top of these firing ranges,there are also options between different firing methods. These methods include oxidation,reduction,salt firings,soda firings,and <a href="https://staging.ceramic.school/raku-firing-with-andrew-cummins/">raku firings</a>. Each one can be fired to different cones as well and some will require special methods to ensure they survive the firing,but each process can produce beautiful and one of a kind results.</p>

<h2>"What is Glaze?" Conclusion</h2>
<p style="text-align: justify;">In conclusion,there is a lot to learn about glaze. It can be confusing for beginners,but we hope that this article helps to make the transition easier for those who are trying to start making their own glazes. Be sure to read our article on how to read glaze recipes to continue your journey into glaze making and testing!</p>

What Is Glaze?

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