Matte vs. Crystalline Glazes: Busting the Myth of the “Matte” Glaze!

Hey everyone, Matt here from Ceramic Materials Workshop! Today, we’re diving deep into the muddy waters of matte and crystalline glazes. And trust me, things aren’t always as they seem in the glaze world!

Now, I know what you’re thinking: “Matt, aren’t matte glazes just, well, matte?” Not so fast, my friend! There’s a whole lot of “matte” glazes out there that are actually wolf in sheep’s clothing – they’re actually crystalline glazes masquerading as matte. And this, my friends, is where the trouble begins.

See, a true matte glaze is a fully melted glass with tiny crystals growing inside it. It’s like a beautiful, microscopic snow globe! These crystals scatter light, giving that soft, velvety surface we all love. But here’s the kicker: a lot of “matte” glazes are simply underfired, meaning they haven’t fully melted. They might look matte, but they lack the durability and true matte characteristics.

And then we have crystalline glazes. Now, when most folks hear “crystalline,” they picture those stunning starburst patterns, like the amazing work of my friend Ian Childers. But guess what? Crystalline glazes come in all shapes and sizes! Those big, dramatic crystals are just one type, formed with zinc silicate. You can also get beautiful crystalline effects with calcium and magnesium, resulting in smaller, subtler crystals.

Here’s the thing that really grinds my gears: “Those smaller crystals are just micro-crystals, right Matt?” WRONG! As Parmelee clearly states in his book, microcrystals need a microscope to be seen. If you can see it with your naked eye, it’s a macrocrystalline glaze, end of story! A true microcrystalline glaze? That’s your matte glaze, folks!

Now, here’s where things get really interesting. Rose and I discovered that all crystalline glazes, regardless of crystal size, live in a specific zone on the Stull map – the Crystallization Zone. And this zone? It’s down in the glossy region, not the matte region! This means they form different types of crystals with different behaviors.

One of the biggest differences? Firing temperature. A true matte glaze? Fire it hot, fire it cool, it’s gonna be matte. But crystalline glazes? They’re divas! Too cool, and you get a mass of tiny crystals. Too hot, and you get no crystals at all. It’s a delicate dance, my friends.

“If you fire too cold, you get too many crystals. If you fire too hot, you get too few.” Write that down! It’s a Matt truism.

And don’t even get me started on firing cycles! Crystalline glazes need that slow cool to let those crystals grow and develop. Matte glazes? They couldn’t care less about your slow cool.

Look, I could talk about this stuff all day, but I’ll spare you. Just remember, there’s a whole lot more to matte and crystalline glazes than meets the eye. Don’t get fooled by those “matte” imposters! Understand the science, experiment, and most importantly, have fun!

And hey, if you really want to nerd out on glazes (and I know you do!), come join us for a class at Ceramic Materials Workshop! We’ll dive deep into glaze chemistry, crystalline glazes, and so much more. We’ll even spill the beans on some secret glaze recipes… maybe. 😉

Keep on crackin’ those kilns!

Matt