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MGBase2 - High Calcium Semimatte 2 (Mastering Glazes)

Modified: 2025-12-30 03:57:01

Base from Mastering Glazes book page 89

Notes

In Mastering Cone 6 Glazes, High Calcium Semimatte 2 (HCSM 2) is the closely related sibling to HCSM 1. It was formulated to offer a slightly "stiffer" melt.

Key Properties
• Visual Appearance: It is a soft, opaque, eggshell-white base. Compared to HCSM 1, it tends to be a bit more opaque and "whiter" providing a dense, velvety look that masks the color of the underlying clay.
• The Science: Like its predecessor, it relies on high calcium levels to create a micro-crystalline surface. It’s modified Alumina:Silica ratio shifts the surface texture and durability.
• Surface: It is a true semimatte. It isn't quite as "shiny" as a semi-gloss, but it isn't "stony" or dry either. It has a refined, smooth feel that is synonymous with the Hesselberth/Roy "functional matte" philosophy.
• Durability: This glaze is a gold standard for chemical stability. It passes a "lemon test" (acid resistance) and "dishwasher test" (alkali resistance) with flying colors.

Likes (Pros)
• Superior Opacity: If you are working with darker stoneware or speckled clay and you want a clean, solid color without the clay showing through, HCSM 2 is often the better choice over HCSM 1.
• Consistency: It is widely considered one of the most stable glazes in the book. It is less prone to "shivering" (glaze popping off) or "crazing" (cracking) than more experimental matte recipes.
• Excellent Color Response: It reacts beautifully with oxide additions. When you add Chrome or Copper, the opacity of the base creates very "solid" colors (like a pastel mint or a solid pink) rather than the translucent, watery colors seen in glossy glazes.
• User-Friendly Application: It generally has excellent "bucket manners." It stays suspended well and creates a nice, even coat on the biscuit ware that doesn't crack as it dries.

Dislikes (Cons)
• Cooling Dependence: Just like HCSM 1, if you don't use a controlled slow-cool in your electric kiln, this glaze can easily fire glossy. Without the time for crystals to grow during cooling, you lose the signature matte finish.
• Flatness: Because it is more opaque, it can sometimes look a bit "flat" or "industrial" if used without any colorants or texture. It doesn't "break" over edges as dramatically as the more fluid glazes like Waterfall Brown.
• Potential for Metal Marking: As with all high-calcium mattes, the microscopic surface crystals can be harder than stainless steel. If used on flat plates, you may eventually see grey cutlery marks (though this is a surface deposit, not a scratch in the glaze).
• Application Depth: If applied too thinly, it can feel a little "scummy" or rough.

Related Information

Links

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