When I was first learning about pottery one of the things that confused me the most was “what was the difference between glazes and underglazes”. Most teachers focused on teaching you wheel throwing or hand building but very few actually teach you about glazing. At least that was my experience. Maybe yours in different…. I hope so… but if not here is a brief introduction to glazes vs underglazes.
Please note this post may contain affiliate links and I may earn a commission if you click them and make a purchase. This is, of course, at no cost to you, and I only share products that I use and love myself.
Glazes, overglazes and underglaze are all materials that can be used to decorate your pots, but they serve a different purpose.
What is a glaze
A glaze is a blend of materials that, when applied to a bisque pot and fired to a particular temperature, will melt and create a glass surface. The melting temperature is determined by the blend and ratios of the materials used to create the glaze. Once in the kiln, the materials in the glaze undergo transformations, fuse onto the pot and eventually the glaze becomes glass.
Glazes can create a smooth, matte, glossy and even a textured surface and can be either opaque or transparent. They also provide a protective layer.
Glazes can be applied over or under each other and how they react to each other determines the final look.
Some glazes are reactive meaning that they may run, change colors and, for the most part, can be rather unpredictable.
Some glazes are very stable and predicable.
I am learning all about the chemistry of glazes and all the ins and outs of the materials used in making them but that is for another time!
If you buy commercial glazes the jar should tell you what temperature range it should be fired at.
No one will be able to tell you how a glaze will look on your clay body or how it will react to other glazes. Thats all about experimenting and experience that comes with it.
What is Underglaze:
Underglazes are what you use to color and decorate your pots when you need more control over the colors.
They can be applied to leather-hard, greenware or bisque pots.
Most of the time a transparent or clear glaze is applied over the underglaze to seal in the color and protect it.
Underglazes usually consist of colored pigments mixed with a binder, such as clay or gum. They are applied to the surface of the unfired pot by painting and you can create some pretty intricate designs.
Although underglazes can be applied to bisqueware, often times the decoration will bleed when the clear is applied so I suggest either painting on greenware and bisque firing the underglaze in and then clear glazing or paint on bisque, and rebisque. This will keep the decoration clean!
I love decorating my pots with underglazes/ There are many manufacturers and you can even make them yourself, but I have found that using commercial ones give the best results and are pretty consistent. My preferred underglaze is Amaco Velvets.
I share some of my techniques and favorite colors here.
Greens can be troublesome. I have found blending Intense Yellow (V391) with blues gives me prettier greens!
Amaco Velvet Jet Black Underglaze is my base color for Sgraffito Work. I apply 3 coats on a Hard Leather hard piece to give a lovely opaque palette to work with. When Bisque Fired it turns a deep matte dark grey. Applying clear glaze brings out the shine and makes it very black.
View on Amazon
Making my own Pottery Glazes These past few months I have really submerged myself in learning all about making my own pottery glazes. I have tried to learn how to make pottery glazes in the past by reading and an online class but my eyes just...
A year ago, I made a very hard decision. I decided to sell my big, beautiful pottery studio and build a small studio on our home property. It had been something I had been thinking about for several years and was just too scared to make the...
Last weekend was my FIRST SHOW for me this year selling my pottery. I have been selling pottery at shows for several years now and it always makes me feel like an artist and proud of my work. My First show of 2023 wa “Airing of the Quilts”. It...