Underglazes

Underglaze is the name given to a type of industrially prepared, stabilized and highly versatile glass engobe. There are several brands of underglaze and they are sold in liquid form, in bottles of different sizes and numerous colors.

It is a more expensive material than engobes, but its applications and uses make engobes sometimes limited. We can apply the underglazes on soft clay, in a leathery state, dry, already shaken or even on the glaze, raw or cooked. Personally, I like painting over dry clay, as the underglaze dries almost immediately and we can then apply a second layer (if necessary). Depending on the consistency of the underglaze and application method, using a brush, for good coverage, we must apply 2 layers.

We can thicken the underglaze (see AC310 medium) to be used in screen printing, for example, or we can thin it to use it more watery like watercolors.

It works well on any type of clay and the bright colors remain at low or high temperatures, although they change a little.

As they are not exactly cheap, you need to manage their use. For small parts, details or specific techniques are worth using; for applying solid colors to larger surfaces or sculpting, I prefer to use engobes or other less expensive options.

Underglazes come in liquid form and contain a type of deflocculant (possibly other ingredients as well) which makes them stay in place once they dry. If we brush over a painting/print made with underglaze, it will not smudge (unless you apply it more vigorously with a brush or sponge). If we hold the piece, our fingers won't smudge the paint. If we paint or print a waved piece and then glaze it, it won't smudge either. On the other hand, this "gum" that incorporates the underglazes makes the surface of the painted piece less absorbent. This is good to know when painting a bisqued piece and then glazing it; The glaze will have a thicker layer in areas that do not have underglaze, as in these areas the glaze is more absorbent. We can take advantage of this effect or avoid it: if the piece goes into the kiln after being painted, the gum will disappear and if we glaze it after firing this no longer happens.

Whether for silkscreen printing, painting/washing with transparent watercolors or opaque colors, applications with the airbrush or with the pear (I prefer bottles with a needle tip, easier to use in my opinion), sponging and splashing, mixing and experiments, this material does not disappoint.

I'm a fan of underglazes for these and a few other reasons. One of the main pretexts for creating this website was to bring to Portugal this material that is so special and so little used here, that I always had to order it from abroad.

I started using the Spectrum ones but they stopped selling that brand in Spain, I tried the Mayco ones and I was very satisfied, that's why I brought them here. I usually use two types of Mayco underglaze:

Fundamentals : underglazes that do not glaze, even at 1200°C. the appearance and texture is earthy and dull. We can always glaze with clear on top if we want.

Stroke & Coat : these underglazes remain glazed after being baked, even if they are applied to raw clay (they work in single firing too).

The 473ml bottles are more affordable than the 59ml bottles, taking into account the quantity/price ratio. Despite having several 59ml bottles, I prefer to buy the primary colors (plus black and white) in 473ml bottles, mix them and get my personalized colors, always recording the approximate portions of each color I used in each mix.

If you choose to try underglazes, I hope you have as much fun as I did! If you have any questions, please contact me and I will try to help.

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