The Colorful World of Majolica Linda Arbuckle

Instructions

The majolica technique is commonly done at low-fire temperatures, although you may work in a similar way on any stiff, opaque glaze at other temperatures with related results. Most of the stain colors used for majolica decorating will fire to mid range (cone 5–6). At cone 10, shino glazes are very viscous and don’t move much, but the available palette of colors is different: many of the purples fire out blue; yellows in reduction are often pale and grayish; most of the pinks burn out; and body stains (e.g. Mason Stain 6020 Pink) may be too refractory even at cone 10. Nevertheless, it maybe worth an experiment or two.

History and Name

Majolica (or maiolica) in common contemporary parlance is a white, opaque, glossy glaze that is very viscous to the point that it doesn’t move during firing. This allows line quality applied to the raw glaze to be maintained faithfully through the firing process.

Historically, Middle Eastern potters developed such glazes for use over an earthenware clay at low temperatures. They used tin oxide to make a white, opaque glaze (usually fluxed with lead) that was a good ground for colored decoration. Work from the Middle East made using this method is identified as tin-glazed earthenware. A raw glaze surface was decorated with copper (green), manganese (plum), and iron or antimony (amber/yellow) over a glaze. Cobalt blues were very popular for decoration, and the blue-on-white echoed Asian high-fire ceramics. Metallic reduced lusterware (done in an additional firing) was also developed in the Middle East, often on a tin glaze.

When the Muslims conquered northern Africa, came north across the Strait of Gibraltar, and created a Moorish influence in Spain from the early 8th century until 1492, they brought their pottery technologies and aesthetics with them. This included tin-glazed pottery methods. Spain exported these wares from Majorca, and Italians began calling this tin-glazed ware majolica.

There are contemporary disagreements about the spelling, pronunciation, and terminology of majolica vs. maiolica. I suspect that the origins of the differences reside in what happens when a Spanish J is transliterated into another language, and complicated by casual use of terms for things that are not technically related. For instance, in the 19th century, companies produced molded relief wares with bright, jewel-like, transparent, colored lead glazes. The Minton company in England was well known for the production of these wares (teapots in the shape of pineapples and cauliflower, cheese bells in the form of beehives, etc.). The bright low-fire color reminded people of Italian majolica-decorated pottery, and the term majolica was used for both, although they are not technically related. I have seen texts that claim that the Minton–style work is done with techniques similar to Della Robbia techniques, but my eyes tell me it’s not so. The tin-glazed work is seen spelled either way. The Minton–style work is usually spelled with a J. Some revisionists insist this is the only way, but very reputable sources, such as the Metropolitan Museum, have spelled the tin-glaze with a J. It seems to be one of those awkward instances where there are variants in spelling and pronunciation, with no one clear “truth.” I pronounce the Maj in Majorca like my, and likewise in majolica, and spell both with a J, but I allow that other spellings and pronunciations are likewise creditable.

Opacifiers

The use of only tin as an opacifier is often modified in contemporary practice. Tin makes a lovely, buttery, very opaque, white glaze. It also increases surface tension in a glaze and may aggravate crawling problems where the glaze is thick (e.g., in corners). Tin in amounts of 5% or above will also cause a color reaction with small amounts of chrome that will cause the tin glaze to turn pink (chrome fuming). This can be delightful if anticipated, but is often not kind to your color plans as a surprise. Many of the green and teal stain colors and some black stains contain chrome, and some rutiles contain small amounts of chrome impurities that can cause chrome-tin pinking in high-tin glazes. For the above reasons, as well as the expense of tin oxide, many artists today use a zirconium opacifier, or a combination of some tin (for denser whiteness) with some zirconium opacifier. This would keep the amount of tin low (say under 4%), yet allow good opacity. Zirconium is weaker than tin in strength, and the usual rule is 1.5% zirconium to replace 1% tin. If chrome-tin pink fuming is a problem, drop the tin a bit, and add that amount multiplied by 1.5 of zirconium opacifier.

Some artists say they enjoy a bit of the terra cotta showing through a translucent white majolica glaze. For me, it darkens the glaze color, damps color response a bit, and makes any thick-thin areas of glaze application more noticeable than a more opaque white. I have  always preferred a very white opaque glaze.

Majolica Colorant Suggestions

Gerstley borate production has been erratic, and the material is variable in quality. It pushes decorating colors toward pastel through very fine reticulation (break up) of the glaze surface, and although I used it when I began majolica, I now use frit as a flux (with bentonite added) or commercial majolica decorating colors.

Colorants mixed with only frit settle quickly, have limited brushability, and are very powdery once dry, making wax resist over the color smudge easily. Some artists, like Matthias Ostermann, use this powdery quality to work the movable surface like pastels. The addition of bentonite or CMC gum to the frit and colorant mix aids brushing and hardens the dry surface. Bentonite doesn’t mix easily with water, so be sure to mix dry bentonite, frit, and colorant first, then add water. Some people find an immersion blender handy. I mix small amounts and generally use a tiny whisk. If something is really lumpy, I will use a small test sieve (60 mesh) and screen the mixture.

I use Ferro frit 3124. Others will work, with color reactions influenced by the specific chemistry of each frit. To aid brushability, you may add a small amount of glycerin (drug store item), or a few drops liquid CMC gum to the liquid mix. Too much glycerin or gum can make a very slippery color mix that moves well but doesn’t apply color in an even thickness.

Colors in studio-mixed oxides or stains and commercial majolica decorating colors will generally mix, but some information about ceramic materials helps. I recommend doing line blends of colors to learn more about mixing and relative strength. Copper melts easily, and will color strongly compared to yellow colors. A nice chartreuse may be four parts yellow by volume to one part mixed copper. With paint, yellow + blue = green. In ceramic colors, blue is made with cobalt, a very strong colorant, while yellow may be a stain made with praseodymium or vanadium, which are weaker colorants than cobalt. Equal amounts of mixed yellow and blue decorating colors may still be very blue, due to the strength of cobalt.

Non-refractory Colorants

1 part colorant, 1 part frit, ½–1 part bentonite:

copper (blue-green), cobalt (blue), manganese (brown to plum with Ferro frit 3110), iron (brown)

Refractory Colorants

1 part colorant, 3–4 parts frit, ½–1 part bentonite:

chrome (grass green), rutile (rusty orange), titanium dioxide (ivory). Most stains are refractory enough to require this ratio.

Note that body stains, like Mason 6020 manganese-alumina pink and Mason 6485 titanium yellow are too refractory for use on top of majolica, even with flux added. Refractory colorants that are not adequately fluxed will result in matte surfaces that are bumpy and/or pig-skinned (crinkled). Testing is the only way to really know.

Soluble Colorants

Cobalt sulfate (blue), copper sulfate (turquoise), manganese chloride (plummy brown), and chrome chloride (green). All are toxic raw. Do not inhale or ingest. They are also absorption hazards: do not handle these without gloves. Soluble colorants are dissolved, rather than suspended, in water, so they wick into the surface of the ware with the water, making a very uniform ground color with a soft edge. If you want any white areas, or to retain clean edges, areas must be waxed before applying soluble colorants. Over-wetting the glaze when applying solubles may move raw glaze and cause color to migrate through the pot wall and/or cause crawling. Too much water on the raw glaze may also cause crawling in the fired glaze.

Commercial Colorants

Some single-coat commercial underglazes work for decorating on top of a majolica base glaze, while others are too refractory. Testing is the only way to determine which ones work. Several companies now make very nice pre-mixed majolica decorating colors. These colors are generally a combination of stains, flux, and vehicles, and they brush well. I suspect that, unlike underglaze colors, the clay content is kept low for more supple brushability.

Application Suggestions

Both the best and worst thing about majolica glaze is that it doesn’t move when you fire it. Having a decent base glaze coating goes a long way toward being happy with the final product. Additionally, large bumps and voids in the raw glaze will leave evidence of brush strokes on top of them and emphasize your glaze application issues.

Apply glaze in the thinnest coating that will give you opacity, and attempt an even glaze coat. Dampen pieces slightly before dipping to remove any dust and moisten the ware for better glaze pick up. Dipping is my mode of choice, although I do know potters who spray effectively. I want to have a container that will allow me to do one dip of the bisqueware. If I have a piece that will not fit in my glaze bucket, say a long, oval platter, I use a different container for dipping. Garden stores often carry metal or plastic 5-gallon oval tubs. Oil change pans can be useful. I have flexible plastic tubs from a garden store that are wider than my 5-gallon glaze buckets, and will allow me to flex the bucket for longer-than-wide shapes and to form a spout to pour my glaze back into the bucket. In a pinch, I have used cardboard boxes reinforced with duct tape or dresser drawers double-lined with heavy trash bags to hold glaze for dipping.

For errors in glazing (and there are bound to be some) 400-grit wet-dry sandpaper will sand down lumps, or they may be gently scraped down with a sharp knife. When sanding or shaving glaze, do it over a container of water to trap the dust and prevent it from circulating in your studio environment. 

Clay Body, Off-Gassing, and Firing Rates

I am still experimenting with firing rates. Several years ago something in clay materials changed and caused gassing in my clay, resulting in many white gas dots in the fired majolica surface, where the base glaze might seal over, but the colorant layer is so thin that it can’t seal and leaves a white spot. Many people maintain that firing slowly is the way to go, and it seems logical that any gas release would be more gentle the slower the firing. On the other hand, I fire many pieces in a small, oval, doll-body test kiln, which cools quickly, and these generally turn out less dotted. The same shapes fired about 200°F per hour in my regular kiln may be more dotted. It’s been an infuriating problem that I continue to research. If you have dotting, try bisque firing as high as you can without making the work too dense to accept glaze. This may drive off gassy materials before glaze application and firing. Bisque at a slower rate, vent your kiln, and glaze thinner if possible. Thinner glaze is less likely to trap the gas bubbles and cause dotting.

the author Linda Arbuckle is a member of the CM Editorial Advisory Board, and is a professor of art at the University of Florida, Gainesville. For more majolica glaze recipes, including a cone 6 version, and additional resources, see her handouts page on her website at http://lindaarbuckle.com/arbuckle_handouts.html.