Blue Spark
PC-11
🟧 Dan Only
Blue Spark is a satin brush-on glaze from Amaco's Potter's Choice line, fired cone 5 to cone 6. Rich, jewel-like, mineral.
SatinOpaqueCone 5/6
Available at The Clay HoleDan only
Order your own bottle any time.
Find it on the glazes shelves
Shelf 4, Row 1Tile #27 on the Potter's Choice pot
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Friendly studio tip for this glaze
Use it on a smooth pot. This one does not break over texture, so any carving you do underneath is work the glaze will quietly cover up.
The quick version of Blue Spark
CoatsThree, even
Stability/fluidityMay run
Breaks over textureNo
TypeBrush-on glaze
FinishSatin
OpacityOpaque
Shows textureNot especially
Glaze fire toCone 5/6
Bisque toCone 04
DifficultyBeginner-friendly
What this glaze does
A glossy royal blue that grows small triangular crystals in dark gray metal as it cools. The reference Amaco reaches for is lapis lazuli, and the comparison holds: deep blue stone with metallic flecks scattered through it.
Unlike most of this line, it does not break over texture. The surface stays even and opaque, and the interest comes entirely from the crystals rather than from the form underneath.
How much it varies
Consistent color. The crystal development is the variable, tied to cooling and thickness.
Clays that suit Blue Spark
Opaque, even, and unaffected by what is underneath. It does not break over texture either, so the clay contributes almost nothing to the finished surface.
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.
Rated forStoneware and porcelain at cone 5 and cone 6, which covers every body on our shelf.
Light bodies#16 Porcelain, B-Mix and Half & Half show these glazes closest to the test tile. Start here if you want the color on the label.
Buff bodies52 Buff and Speckled Buff run warmer and let iron specks come up where the glaze thins. On the see-through glazes that speckle is often what makes the pot.
Berlin GrayOur dark body, and the one that changes these glazes most. Anything see-through goes deeper and quieter on it.
Chasing pinholesAmaco reports this line clearing up on a smooth, low-grog body more often than not. Worth trying before you blame the glaze.
Applying this glaze to your work
Amaco asks for three even brush coats specifically. Even matters more here than heavy, since the surface is meant to read as a single consistent field.
How much it moves
Amaco's own note is short and worth repeating: the glaze may run. Leave clearance at the foot.
Across the Potter's Choice line
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
Because it does not break and does not want interruption, it works best as a finished surface on its own rather than as half of a pair.
Before you commit a pot
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 Blue Spark 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 Blue Spark
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. The crystals form during cooling, so a normal cooling cycle is doing real work on this glaze.
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 Blue Spark
Why are there no crystals in mine?
They develop as the kiln cools. A fast cool or a thin coat both reduce them.
Why is my texture invisible under it?
This glaze does not break over texture, by design. If you want relief to show, this is the wrong glaze for that pot.
Why did it run?
Amaco warns it may. Three coats of a glossy blue on a vertical wall will move.
What to put it on
Forms and surfaces
Smooth, simple forms where a rich even blue is the whole idea. Since texture disappears under it, save it for shapes that do not need help.
Colors beside it
A saturated royal blue with gray metal in it. It sits well against white, cream and unglazed clay, and it fights most other strong colors.
Food and function
Amaco rates this glaze food safe and dinnerware safe, lead free and AP Non-Toxic.
Across the Potter's Choice line
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 #27. 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
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.
Other glazes close to Blue Spark
June Bug does the same crystal trick in dark green. Indigo Float gives deep blue with a float instead of crystals. Tourmaline holds an even blue-green with no crystals at all.
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: 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.
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.