Mayco Black Walnut Glaze Review: SW-104 Coats, Cones and Combinations

Verdict

Mayco Black Walnut is a good pick if you want a calm, dark brown matte that shows carving and throwing lines, at cone 6 or cone 10. It is easy to like and hard to ruin: Mayco's own guidance is mostly about thickness, and the glaze sits still compared with Mayco's reactive floats. The catch is coverage. Mayco asks for four or more coats for the full color, so it uses more glaze per pot than many brushing glazes, and Mayco publishes only a few combinations with it.

This review is research-based, built from Mayco's product page, Stoneware user guide and dinnerware page, plus dealer listings, in October 2026. We did not fire this glaze ourselves.

Black Walnut at a glance

What Black Walnut looks like

At cone 6 oxidation, Mayco describes "a dark brown soft matte glaze that breaks a rich warm brown". Where the glaze thins over rims, edges and carved lines, it turns lighter and warmer, which is what makes texture stand out. At cone 10 reduction, Mayco says "rich brown undertones come through".

Mayco's use tip is simple: "The thinner the application, the lighter brown the color. The thicker the application, the darker the brown color." Its page uses both "soft matte" and "satin" for the finish, so expect a smooth surface with a low sheen rather than a dry, chalky matte.

On light and dark clay

Mayco's chips are "fired flat on a white clay body", and Mayco does not publish results on dark or red clay. On a white or buff body you get the colors in Mayco's photos. On a dark stoneware, expect the thin breaks to read darker, since less light clay shows through, and test before a full batch. Our dark clay bodies page covers how bodies change glaze color.

How many coats of Black Walnut?

Mayco says "for a saturated opaque finish, apply 4+ coats", and its product page shows chips at one to four coats. Fewer coats are a valid choice: one or two coats give a lighter, more transparent brown that shows the clay. Mayco's general Stoneware guide recommends two to four coats depending on how heavy the application is, three coats for wheel-thrown and hand-built pieces, and two for slip cast. For Black Walnut's full color, aim for the top of that range.

1. Shake and stir the pint well.
2. Load a soft brush fully and lay on a smooth coat.
3. Let each coat dry until the shine is gone before the next.
4. Build to four coats on outer walls for a solid dark brown; stop at two where you want lighter breaks.
5. Wipe the foot clean and keep glaze off the bottom.

Our how to glaze pottery guide covers brushing, dipping and checking thickness.

Dipping Black Walnut

For dipping, buy SD-104, the 10 lb dry version. Mayco says dry Stoneware glaze must be mixed thoroughly with distilled water to the package directions, and recommends a single dip for results like its sample tiles. Wear a NIOSH-approved respirator when mixing the dry powder, wet-mop spills and never dry sweep glaze dust.

Pint or 10 lb dry: which to buy

Buy the SW-104 pint if you brush. Because Black Walnut needs four or more coats for full color, one pint covers fewer pots than a glaze that looks right at two coats, so buy two pints if you plan a set of mugs or bowls. Buy SD-104, the 10 lb dry bag, if you dip: mixed with distilled water to Mayco's directions, it fills a bucket and Mayco says a single dip matches its sample tiles. Dry glaze also stores well until you mix it.

Does Black Walnut run?

Mayco does not give Black Walnut a running warning, and it is not one of the line's fluid floats or crystal glazes. Mayco does say Stoneware mattes "create interesting color variations as they move and break", and its guide warns that added heat work makes any glaze more fluid, so it asks you to "leave some space for movement when testing vertically". Keep a glaze-free band at the foot, test on vertical tiles, and fire to the cone you tested. Layered with a Flux glaze, expect more movement than Black Walnut alone.

Black Walnut layering combinations

Mayco publishes three Black Walnut layering results on the SW-104 page:

• Black Walnut over SW-401 Light Flux and over SW-402 Dark Flux, cone 6 oxidation.
• Black Walnut under SW-401 Light Flux and under SW-402 Dark Flux, cone 6 oxidation.
• Black Walnut under SW-401 Light Flux and SW-402 Dark Flux, cone 10 reduction.

Flux glazes are made to pull and break the glaze they touch, so these pairings show Black Walnut at its most varied. Our Mayco Flux glazes page covers that line. Mayco's searchable combination database returned no other Black Walnut entries when we checked, and combinations such as Green Tea over Black Walnut on dealer sites are dealer specials, not Mayco tests.

Is Black Walnut food safe?

Mayco shows a dinnerware icon on the SW-104 page, and its 2026 Stoneware guide lists SW104 as dinnerware safe with an ACMI CL label. Two details matter. First, the CL seal means the product carries caution labeling, and Mayco says CL products "should never be given to children age 12 and under". Second, Mayco's dinnerware page says it now uses "suitable for dinnerware", meaning food-contact use when fired to the maker's directions, and that layering is "not automatically" covered.

Mayco SW-104 Black Walnut

Black Walnut is picked as Mayco's most straightforward dark brown matte: one color, a clear coat guide, and results published at cone 6 and cone 10. It suits carved, stamped and fluted work where a breaking matte shows detail.

• Finish: soft matte to satin, opaque, breaking
• Cone: 6 oxidation target; cone 10 reduction results shown
• Coats: 4+ for saturated color; fewer for lighter brown
• Sizes: SW-104 pint; SD-104 10 lb dry
• Label: dinnerware icon; ACMI CL

Who should skip it: potters who want gloss, bright color, or a one-coat glaze; and teachers of children 12 and under.

What Black Walnut does well

• Breaks warm brown over texture, edges and throwing lines.
• Stable, quiet surface compared with Mayco's floats.
• Works in oxidation at cone 6 and reduction at cone 10.
• Pints and a 10 lb dry bag for dipping.

Weak points

• Four or more coats for full color uses glaze quickly.
• Mayco publishes only Flux combinations with it.
• No results on dark clay published by the maker.
• Wood and soda results "will vary", says Mayco; see soda firing.

Who should buy it, and who should skip it

Buy Black Walnut if you fire to cone 6 or cone 10, like earthy, matte surfaces, and make textured or carved pots. Skip it if you want a glossy brown with movement, which Mayco's Tiger's Eye covers better, or if you want to brush one or two coats and be done.

Alternatives

Mayco SW-122 Maycoshino

Maycoshino is picked for potters who like Black Walnut's earthiness but want more variation. Mayco shows reddish brown at one coat, cream to tan breaking brown at two, and cream waves at three. Our shino glaze guide explains the shino style.

• Cone: 6, with cone 10 results shown
• Sizes: SW-122 pint; SD-122 10 lb dry

Who should skip it: potters who want a solid, dark brown.

• Mayco SW-112 Tiger's Eye: glossy, deep reddish brown to frothy amber at cone 6 that moves but, per Mayco, will not run off the ware. See Mayco Tiger's Eye.
• Mayco SW220 Black Timber: a satin, mottled brown with shiny brown crystals. See Mayco Black Timber.
• For the whole line, read our Mayco Stoneware glazes review.

Sources: Mayco product pages for SW-104 Black Walnut, SW-112 Tiger's Eye and SW220 Black Timber; Mayco "Glazes + Engobes User Guide" (revised April 2026); Mayco Dinnerware Suitability and ACMI Information page; Mayco Stoneware fired color page and Glaze Combinations database; Mayco SW122 Maycoshino combination sheet; dealer listings at Dick Blick, The Potter's Shop, Creative Crafts and Alabama Art; Ahrefs SERP data for "mayco black walnut". Specs checked October 2026.