Mars Crystal

CO-13

🟧 Dan Only

Mars Crystal is a glossy brush-on glaze from Amaco's Cosmos line, fired cone 5 to cone 6.

GlossyOpaqueCone 5/6
Available at The Clay HoleDan only Order your own bottle any time.
Test tile
Fired pot
Cosmos family
Find it on the glazes shelves Shelf 4, Row 1Tile #1 on the Cosmos pot
Show me where

The quick version of Mars Crystal

TypeBrush-on glaze
FinishGlossy
OpacityOpaque
Shows textureNot especially
Glaze fire toCone 5/6
Bisque toCone 04

What this glaze does

Mars Crystal is a highly fluid, dark brick red glaze with silvery, iridescent crystals.

Clays that suit Mars Crystal

Rated forCone 5 and cone 6 over cone 04 bisque. Amaco says the line performs best at cone 5.
Any stonewareThe crystal effect comes from the glaze rather than the clay, so body choice matters less here than in our transparent lines.
Dark bodiesBerlin Gray gives the crystals more to contrast against, which suits a line built on shimmer.
RunningThese are highly fluid. Amaco recommends stopping the glaze about half an inch above the foot and using a drip tray or soft brick to protect the shelf.
Ask firstBecause this line runs, check with an instructor before putting it on anything with a tight foot or a flat base.
Blocks of clay in the studio at The Clay Hole The complete guide to clay bodies What each body is made of and how it behaves under a glaze. The clay bodies we stock at The Clay Hole The clays we carry Every body on our shelf, with bag sizes and prices.

Applying this glaze to your work

Four coats to cone 04 bisque. Amaco recommends leaving the inside or the back of the form unglazed, and stopping the glaze about half an inch above the foot because this line runs.

Across the Cosmos line

Four coats to cone 04 bisque. Amaco is specific about the number.

They also recommend leaving the inside or the back of the form unglazed, because these run.

From The Clay Hole University

More info about Mars Crystal below, but first... Everything we teach about glazing, written down and taught properly. These are the glaze lessons, and they are a small corner of a library that runs from centering your first pot to selling your work.

Glaze Brushing Techniques, Coat by Coat GuideGlaze Brushing Techniques, Coat by Coat Glazing Big and Intricate Pottery Faster GuideGlazing Big and Intricate Pottery Faster Getting the Most Out of the Mega Glaze Tool GuideGetting the Most Out of the Mega Glaze Tool Making, Logging and Dialing in Test Tiles GuideMaking, Logging and Dialing in Test Tiles Glaze Problems, Causes and Fixes GuideGlaze Problems, Causes and Fixes Glazing on the Wheel for Even Coats and Clean Bands GuideGlazing on the Wheel for Even Coats and Clean Bands Bubble Glaze with Dish Soap GuideBubble Glaze with Dish Soap Mixing Your Own Glazes: What It Actually Involves GuideMixing Your Own Glazes: What It Actually Involves Making a Glaze Catcher GuideMaking a Glaze Catcher Getting Great Results with Crystalline Glazes GuideGetting Great Results with Crystalline Glazes Oxide and Carbonate Washes GuideOxide and Carbonate Washes When to Use Celadon Glazes GuideWhen to Use Celadon Glazes How to Use Dipping Glazes GuideHow to Use Dipping Glazes Raku Firing: Techniques, Tips and How It Works RakuRaku Firing: Techniques, Tips and How It Works How to Use Underglaze: Techniques, Rules and Firing UnderglazeHow to Use Underglaze: Techniques, Rules and Firing Mishima: How to Inlay Slip and Underglaze into Carved Lines UnderglazeMishima: How to Inlay Slip and Underglaze into Carved Lines Wipe-Away Texture: Underglaze and Oxide Washes on Bisque UnderglazeWipe-Away Texture: Underglaze and Oxide Washes on Bisque
Browse all 170+ lessons and guides

Firing Mars Crystal

Amaco rates the Cosmos line for cone 5 and cone 6 over bisque fired to cone 04, and says it performs best at cone 5. No special cooling schedule is required, though a controlled cool grows more crystal.

If you are a member here

None of this is yours to manage. We handle everything on the kiln side, and every glaze on our shelves can be fired safely in our studio.

Common problems with Mars Crystal

Why did it run onto the shelf?

Cosmos glazes are highly fluid. Amaco recommends stopping about half an inch above the foot and using a drip tray or soft brick.

Do I need a special cooling schedule?

No. A normal medium speed firing works, though a controlled cool grows more crystal.

Can I drink from it?

Amaco does not recommend this line for food surfaces.

Food and function

Amaco rates the line food safe as a material but does not recommend it for food surfaces, because the surface is not durable enough for it. Use it on the outside of pots and on decorative work.

Across the Cosmos line

Amaco rates the Cosmos line food safe as a material and still does not recommend it for food surfaces, because the surface is not durable enough.

Use it on the outside of pots and on decorative work.

Test tile pots lined up on the glaze shelves at The Clay Hole

Our test tile pots

Every glaze family on our shelves has its own test tile pot, and it is the fastest way to decide what to put on a piece. It is a fired pot wearing the whole family, one numbered tile per glaze, on a surface built to show you what that glaze actually does rather than just what color it is.

  1. 1Find the pot The brand and family name are written on the rim. This glaze lives on the Amaco Cosmos pot.
  2. 2Find the tile This one is tile #1. The numbers match the ones in the Glaze Bible.
  3. 3Read it properly Look at what the glaze does across all four textures, not just what color it is.

What to look at on the tile

Broad vertical textureA broad open surface. Shows the color at full strength, and whether the glaze travels down it.
Shallow textureA shallow swirl stamp. Shows whether light carving still reads once the glaze is on, or fills in and vanishes.
Deep textureCut lines. A deeply rough texture stripe. Shows where the glaze pools, how it breaks, and how dark it goes in the recesses.
Wipe-away textureGlaze wiped back to bare clay. Shows what the edge does where the coat runs thin. Find this wiped away on the tile's number.
One trick worth knowing

Some glazes tell you loudly that they run. Others hide it. Look at how the brushed lines fired: crisp edges mean a stable glaze, and edges that went soft and fluid mean it moved, and it will move on your pot too.

About the Amaco Cosmos Family

Cosmos is Amaco's crystalline line, built to give microcrystalline surfaces without a special firing schedule.

The glazes are highly fluid and grow crystals as they cool, which is where the shimmer and the flowing surface come from.

Five glazes here out of Amaco's eight, rated for cone 5 and cone 6 over cone 04 bisque. Amaco recommends four coats and says the line performs best at cone 5. No controlled cooling is required, though a controlled cool will grow more crystal if you have that option.

All Cosmos glazesAll Amaco glazes
Cosmos family

More ways to pick a glaze

The Mega Glaze Tool Every glaze we carry, filtered by level, color, sheen and more. The Glaze Finder Type a name and see exactly where it sits on our wall. Clay Hole University Glazing lessons, from brushing to dipping to layering. Download the Glaze Bible PDF The whole printed Bible, in one file.

Membership levels that may use this glaze: None. This glaze is in the studio for Dan's use only. You are welcome to buy your own bottle.

Not sure whether this glaze suits what you are making, or how it works with our system here? Ask an instructor. That is what we are here for, and a two minute conversation at the shelf beats a fired pot you did not want.

How membership levels work Back to the Glaze Bible
About these images and what your pot will actually look like

We have done our best to represent every glaze here accurately, and you should still expect your pot to look different from what is on this screen.

Our glaze tile images are digitally created. They are built to show the character of a glaze, not to be a color match.

A screen is not a printout, a printout is not a test tile, and a test tile is not a finished pot. Each step in that chain shifts what a glaze looks like, sometimes a lot.

On top of that, the pottery itself changes the result: the clay body, how thick the glaze went on, whether it was brushed, dipped or sprayed, what was layered under or over it, where the piece sat in the kiln, how hot that spot ran, how fast it cooled, what was fired next to it, and how much texture the surface had. Two pots glazed from the same jar on the same day can come out different.

Treat every image here as a starting point, and treat a test tile fired on your own clay as the real answer.

Download the Glaze Bible PDF