Purple Crystal
PC-16
Purple Crystal is a satin brush-on glaze from Amaco's Potter's Choice line, fired cone 5 to cone 6. Deep purple, crystalline, rich.
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Friendly studio tip for this glaze
Find out where your firing lands before you judge it. Cooler gives a matte violet, hotter gives a glossy indigo with purple crystals, and they look like two different products.
The quick version of Purple Crystal
What this glaze does
A glaze with two distinct personalities at either end of its range. At cone 5 it is a matte violet. At cone 6 it turns glossy deep indigo and grows purple crystal floats on the surface.
That is a bigger difference than most glazes show across one cone, and it means where your kiln lands genuinely decides which glaze you get.
How much it varies
Predictable once you know your kiln, and confusing until then, because cone 5 and cone 6 give genuinely different surfaces.
Clays that suit Purple Crystal
Opaque over stoneware and porcelain. The dramatic difference in this glaze comes from the cone rather than from the clay.
Thirty three of these forty six glazes are opaque, so on most of them the clay underneath is a surface to sit on rather than part of the finished color. The other thirteen see through to some degree, and those are the ones where your clay choice really shows.
Applying this glaze to your work
Three coats. The crystal floats at the hot end need a full application to develop.
How much it moves
Standard clearance at the foot.
Amaco's instruction for the line is three brush coats, not thinned, each one dry before the next. Their own guidance says most disappointing results come from glaze applied on the light side. Amaco publishes an application guide showing what too thin and too thick actually look like.
Layering
With two very different finishes depending on temperature, this one is worth understanding alone before adding a partner.
Amaco's own combination tiles usually show two coats of each glaze, which lands four coats total anywhere the two overlap. Their standing advice is to test a tile before committing a piece, and to re-test when a new batch number arrives, since raw materials shift between production runs. Dipping versions of these glazes behave differently from the brushing jars and are much harder to layer.
From The Clay Hole University
More info about Purple 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.
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
Firing Purple Crystal
Amaco rates the line for cone 5 and cone 6, published as 2167F and 2232F on a medium speed firing, over bisque fired to cone 04. This glaze is the clearest example in the line of why the cone matters: matte violet at cone 5, glossy indigo with purple crystals at cone 6.
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 Purple Crystal
Why is mine matte violet with no crystals?
It fired at the cool end. Crystals and gloss are the cone 6 behavior.
Why does it look nothing like the photo I saw?
Check which cone the photo was fired to. This glaze legitimately looks like two different products at each end of its range.
What to put it on
Forms and surfaces
Smooth and lightly textured forms where the crystal floats can be seen. Good on pieces where a purple is wanted without going pastel.
Colors beside it
Deep violet and indigo are strong. Cream, gray and bare clay give them room; warm golds beside them read as luxurious.
Food and function
Amaco rates this glaze food safe and dinnerware safe, lead free and AP Non-Toxic.
Every glaze in the line is lead free and, by Amaco's rating, dinnerware safe except PC-4 Palladium and PC-64 Aventurine. Amaco's own label carries the standard caution that anyone producing tableware should test finished ware, because firing temperature and contamination vary between kilns.
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.
- 1Find the pot The brand and family name are written on the rim. This glaze lives on the Amaco Potter's Choice pot.
- 2Find the tile This one is tile #28. The numbers match the ones in the Glaze Bible.
- 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
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.
Other glazes close to Purple Crystal
Smokey Merlot is the warm purple with a lilac float. Indigo Float covers the deep blue ground. Blue Spark gives crystals in royal blue.
Looks great paired with
Put these on the shelf beside it, or on the next pot in the same set.
About the Amaco Potter's Choice Family
Potter's Choice is the line Amaco built so an electric kiln could do what a gas kiln does. Released in 2004, it reaches for the depth of cone 10 reduction glazes at cone 5 and cone 6 in ordinary oxidation. That is the whole premise, and it is why the surfaces break, pool, float and shift instead of sitting flat.
It is one of the most layered brushing lines in American pottery, and Amaco keeps a public library of combination tiles for it. Most of the effects potters chase come from two of these glazes meeting on one pot.
Made by Amaco, a company that has been building glazes and kilns in Indianapolis since 1919. The Potter's Choice line arrived in 2004 and has been a reference point for mid-fire reduction looks since.
More ways to pick a glaze
Membership levels that may use this glaze: Purple & Black
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.
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.