Cosmos
5 glazes / Amaco
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.
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Cosmos by the numbers
Friendly studio tip for this glaze family
These run. Not a little, a lot.
Amaco says to stop the glaze about half an inch above the foot and to use something under the pot to catch what comes down. Take that seriously, because a crystalline glaze that reaches the shelf takes the pot with it.
Four coats, cone 5 for the best result, and leave the inside alone.
Every Cosmos glaze we have in house
Hover any tile to see a pot fired in it, or tap once on a phone.
How the Cosmos line works
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.
Coats
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.
Layering
Cosmos is its own finish. The crystal growth is the effect and covering it defeats the point.
If you want to try a pairing, use a tile first.
Food and safety
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.
Clays that suit Cosmos
From The Clay Hole University
More info about Cosmos 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.
GuideGlaze Brushing Techniques, Coat by Coat
GuideGlazing Big and Intricate Pottery Faster
GuideGetting the Most Out of the Mega Glaze Tool
GuideMaking, Logging and Dialing in Test Tiles
GuideGlaze Problems, Causes and Fixes
GuideGlazing on the Wheel for Even Coats and Clean Bands
GuideBubble Glaze with Dish Soap
GuideMixing Your Own Glazes: What It Actually Involves
GuideMaking a Glaze Catcher
GuideGetting Great Results with Crystalline Glazes
GuideOxide and Carbonate Washes
GuideWhen to Use Celadon Glazes
GuideHow to Use Dipping Glazes
RakuRaku Firing: Techniques, Tips and How It Works
UnderglazeHow to Use Underglaze: Techniques, Rules and Firing
UnderglazeMishima: How to Inlay Slip and Underglaze into Carved Lines
UnderglazeWipe-Away Texture: Underglaze and Oxide Washes on Bisque
Common questions about Cosmos
How many Amaco Cosmos glazes does The Clay Hole carry?
Five of Amaco's eight, and every one has its own page here with test tile and fired pot photos.
What cone do Cosmos glazes fire to?
Cone 5 to cone 6 over bisque fired to cone 04. Amaco says the line performs best at cone 5.
Are Cosmos glazes food safe?
Amaco rates them food safe as a material but does not recommend them for food surfaces because of durability. Use them on the outside.
How many coats do Cosmos glazes need?
Four, and Amaco recommends leaving the inside or back of the form unglazed.
Do Cosmos glazes need a special cooling schedule?
No. Amaco says a normal medium speed firing is enough, though a controlled cool grows more crystal.
Do they run?
Yes, noticeably. Amaco recommends stopping the glaze about half an inch above the foot and protecting the kiln shelf.
The Cosmos test tile pot
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.
Look for Amaco Cosmos written on the rim. Each glaze on this page carries its tile number, and the numbers run around the pot.
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 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.