Applying Pottery Inks to Finished Pottery
Prisme, the enamel colors and the glass colors all go on a pot that is already finished, and none of them sees a kiln. Two cure in a kitchen oven at 300 F and one only ever air dries. They are the answer when you want color on a pot that is already out of the kiln, and they come with limits worth knowing before you start.
Three different products, three different rules. Enamel bakes at 300 F and survives the top rack of a dishwasher. Glass color bakes the same way and stays transparent. Prisme air dries into a honeycomb and never gets baked hard. None of them is food safe.
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Outside tables only
None of this happens inside the studio. The enamel colors, the glass colors and Prisme are all solvent based, they all smell, and none of them is fired. They go on the tables outside, and they dry out there too.
The baking is a different question again. It needs a kitchen oven, which we do not have, so that part happens at home.
The water based version of the enamel colors exists and is much milder, and it is still an outside job here, because the rule is about what gets used in a shared room rather than about any one bottle.
Three products, three different answers
People say "pottery inks" as if it were one thing. It is three, and mixing up their rules is where the wasted afternoons come from.
- Enamel color. Opaque, lacquer-like, the workhorse. Air dries, then bakes at 300 F for 35 minutes and becomes genuinely durable.
- Glass color. Transparent, made for light coming through it, and it bakes the same way. Use it where you want the glaze underneath to still show.
- Prisme. The honeycomb effect. It air dries into cells all by itself, takes days to fully cure, and never becomes hard. Decorative only, and baking it dulls it.
Not one of the three is food safe.
The route that works first time
Eight steps, on the outside tables, using the enamel colors on a glazed pot.
- Take it outside. Paints, thinner, rags, all of it.
- Wipe the pot with rubbing alcohol and let it dry. Color crawls off a greasy glaze.
- Mask the rim and anything food touches. It is not food safe and the tape takes a minute.
- Stir, do not shake. The color settles in the bottle and shaking puts bubbles in it.
- Paint deliberately and stop. These do not like being reworked. Lay the color and leave it rather than going back over a drying edge.
- Build opacity in layers, letting each one dry, instead of loading one thick coat.
- Let it air dry 24 hours. Not optional. Baking a wet coat traps solvent and clouds it.
- Bake it in a cold oven. Put the pot in, turn it on to 300 F, give it 35 minutes from temperature, then turn the oven off and let the pot cool inside it. Cold pot into a hot oven is how pots crack.
Three things ruin nearly every piece
The pot went into a hot oven
Thermal shock. A cold glazed pot dropped into a preheated oven can crack or, at worst, come apart. It goes in cold, heats with the oven, and cools inside it with the door shut.
You reworked a drying edge
These paints skin over fast and hate being touched once they start. Going back over a half-dry area drags it into ridges that bake in permanently. One pass, then leave it alone.
You baked it before it was dry
Twenty four hours of air drying first. Heating a wet coat boils the solvent out through the surface and leaves it cloudy, bubbled or tacky forever.
Read the differences, watch the hands
Almost everything written about these products online treats them as craft paint, which is fine if you are decorating a dollar store plate and unhelpful if you are putting them on a pot you spent three weeks making.
So this page is organized around the three products and the one thing that actually differs between them, which is what happens after you put the color on. Seven videos sit next to the sections they belong to.
One honest framing. This is the route for people who want color on a pot that is already finished, or who want effects no kiln can produce. If the piece is still unfired, underglaze will give you better color, permanently, for less money and less fuss.
The three products, and what each is for
They sit next to each other on the shelf in nearly identical bottles, and they behave nothing alike.
Enamel color, the workhorse
Opaque, glossy, lacquer-like. Goes on almost any heat-stable surface: glazed pottery, porcelain, terracotta, glass, metal. Air dry 24 hours, then bake at 300 F for 35 minutes and it becomes permanent, solvent resistant and fine on the top rack of a dishwasher. This is the one to start with.
Glass color, the transparent one
Same family, same baking, built to let light through. On a glazed pot it tints rather than covers, so the glaze underneath keeps doing its job. Layer it for depth. Use it where you want color without hiding the surface.
Prisme, the effect one
Opaque and solvent based, and it does something none of the others do: as it dries it separates into a honeycomb of cells. You do not make the pattern, the drying makes it. Air dry only, never properly hard, and it takes weeks to fully cure.
Markers
The enamel colors in pen form. Far better than a brush for lettering, outlines and fine lines, and they bake on the same schedule. The single easiest way into this whole category.
Outliner and relief
A thick paste in a nozzle tube that stands proud of the surface. Used to draw raised lines, or to build a dam that keeps two colors from running into each other. Bakes with everything else.
Thinner and gloss medium
The thinner revives a bottle that has thickened and cleans brushes. The medium extends a color and makes it more transparent without weakening the bake. Neither is essential on day one.
The water based option
There is a water based version of the enamel colors. It is much milder to work with, cleans up with water and bakes the same way. It is a good choice if the solvent smell is the thing putting you off. The color range is smaller and the finish is slightly less glassy.
What to put them on
Anything that will take 300 F without complaining, which is most of what comes out of our kilns and not all of it.
- Glazed stoneware and porcelain. The obvious home for this. Glossy glaze gives the crispest edges, matte gives a softer, more absorbed look.
- Bare bisque and terracotta. Both work. They are porous, so the first coat sinks in and the color reads duller. Plan on two or three coats.
- Not a piece with an overglaze on it. Gold and other lusters are a thin metal film, and baking paint over one risks lifting it. Decide which finish the pot is getting.
- Not a cracked or badly crazed pot. An oven cycle, even a gentle one, opens up existing flaws. If a pot has a crack, this is not the moment to test it.
- Nothing with metal fittings, cork or glued parts. Take them off first. 300 F is nothing for clay and plenty for glue.
- Clean first, always. Alcohol on a lint free cloth, then let it dry. Every fingerprint and every trace of kiln dust is a place the color will crawl away from.
Putting them on
These reward a confident hand and punish fiddling. The single biggest change most people need to make is to stop touching an area once they have painted it.
- Stir rather than shake. The color settles and the effect particles in Prisme settle hardest. Shaking puts bubbles in that bake in as pits.
- One pass, then walk away. They skin quickly. Brushing back over a half-dry edge drags it into ridges, and no amount of later work smooths that out.
- Build opacity in layers, not in thickness. Two or three thin coats with drying time between them beat one heavy coat, which stays soft in the middle and bakes cloudy.
- Work small areas at a time on a curved pot, and turn the piece so you are always painting on a surface that is nearly level. Gravity pulls a wet edge downhill faster than you expect.
- Use the outliner to build dams where two colors meet and you want them to stay apart. It is the difference between a clean design and a bled one.
- Mistakes lift with thinner while wet, and with a scalpel once dry and before baking. After baking, what you have is what you have.
- Markers for anything fine. Lettering, outlines, dots, thin lines. A brush will fight you on all four.
The mistake nearly everyone makes first
Treating it like acrylic. Acrylic tolerates blending, reworking and pushing color around. These do not. They behave more like nail polish, and the people whose pieces look best are the ones who decided what the stroke was before they made it.
Prisme, which behaves differently
Prisme is the reason people go looking for this category in the first place, and it plays by none of the rules on the rest of this page.
- The pattern makes itself. Poured thickly and left alone, it separates as it dries into a honeycomb of cells. You control where it goes and roughly how big the cells are. You do not control the pattern.
- Thick is the whole point. Thin Prisme is just glossy paint. It needs a real pool of it to break into cells, which is why people apply it with a pipette or straight from the bottle rather than with a brush.
- A toothpick beats a brush. Bristles fight the surface tension the effect depends on. Push it around with a toothpick or a cocktail stick instead.
- Keep the pot level while it sets. On a curve it runs and pools at the bottom. Turn the piece every few minutes for the first stretch if you are working on a vertical wall, or accept a drip as part of the design.
- You cannot see the result while it is wet. The cells appear as it dries, over hours. Judging it early and adding more is the usual way people ruin it.
- It never gets truly hard. It looks cured long before it is, and even fully cured it dents and marks. Do not bake it to speed it up: heat yellows it and flattens the depth.
- Layering works. A second Prisme color over a dry first one gives contrasting cells, and Prisme over the glass colors does something different again.
Where it belongs on a pot
Prisme is for pieces that get looked at rather than handled: a panel on a vase, a band on a lamp base, the inside of a decorative bowl. Anywhere it can be touched regularly, it will eventually show a mark.
Baking, and the rule that cracks pots
This part happens at home, in a kitchen oven. It is simple, and one detail in it is the difference between a finished piece and a broken one.
- Air dry 24 hours first. Not until it feels dry. Twenty four hours. Solvent still in the coat has to leave before heat arrives.
- Put the pot in a cold oven. This is the rule. Clay and glaze do not like sudden temperature change, and a cold pot into a preheated oven is how a piece cracks or breaks.
- Set it to 300 F and start counting the 35 minutes from when the oven reaches temperature, not from when you turned it on.
- Turn the oven off and leave the door shut. Let the pot cool inside, all the way. Pulling a hot pot out into room air is the same shock in reverse.
- Expect a smell. Open a window and run the extractor. It passes.
- Prisme does not get baked. Heat yellows it and flattens the effect. It air cures, slowly, and that is the only route.
After it is baked
The enamel and glass colors come out permanent, solvent resistant and fine on the top rack of a dishwasher. That is genuinely durable for a paint. What it is not is fired, so it is still a coating on a pot rather than part of one, and it will not survive a knife, a scouring pad or a very hot pan.
What goes wrong, and what caused it
The pot cracked in the oven
It went into a hot oven, or came out into cold air. Thermal shock, and it is the only failure on this page that destroys the pot rather than the paint. Cold oven in, oven off and door shut on the way out.
The finish came out cloudy or bubbled
Baked before it was properly dry, or applied too thickly. Solvent trapped under the surface boils out during the bake. Twenty four hours of air drying and thinner coats.
Ridges and drag marks
The area got worked after it started to skin. There is no fixing this after baking, and not much before. One confident pass per area is the technique.
The color crawled away from a spot
Oil or dust on the glaze. Wipe with alcohol, let it dry fully, and handle the clean pot as little as you can before painting.
Prisme never made cells
Applied too thin, or brushed out. The effect needs a real pool and it needs to be left alone. It also will not show while wet, so give it hours before you decide it failed.
Prisme went yellow and flat
It got baked. Heat is exactly what Prisme does not want. Air cure only, and be patient, because it takes weeks rather than days to finish curing.
The colors bled together
Two wet areas touched. Either leave a gap, or let the first color dry fully, or lay an outliner dam between them before you start.
It scratched off in use
Even baked, it is a coating rather than a glaze. Knives, scouring pads and stacking will take it off. It goes on surfaces that are seen, not surfaces that get worked.
What you can claim afterward
These sit in an awkward middle: much tougher than most craft paint, nowhere near a fired glaze. Being precise about that is what keeps a customer happy.
- Not food safe. The manufacturers say so plainly. They have not been tested for what happens if they end up in food, so they stay off rims, off inside surfaces, off anything a mouth meets.
- Dishwasher safe, top rack, once baked. For the enamel and glass colors only, and only if you actually baked them. Prisme is not.
- Not microwave safe. Some of these colors carry metallic pigment, and none of them are designed for it.
- Not oven safe. Baking to cure is one 35 minute cycle. It does not make the pot a baking dish.
- No knives, no scouring. The surface scratches. Say so when the piece changes hands.
- Prisme is decorative only. Not washed, not handled, not near food. A panel to look at.
The honest one line version
A baked enamel piece is a decorated pot that can be washed. It is not a food surface and it is not a glaze, and any description that blurs those two is the one that comes back.
The bench checklist
The left one before you paint, the right one before the pot goes in the oven.
Before you paint
- Working outside, not in the studio
- Pot has no cracks or bad crazing
- No luster or overglaze already on it
- Cork, metal and glued parts removed
- Wiped with alcohol and fully dry
- Rim and food surfaces masked off
- Bottles stirred, not shaken
- Know which product is in my hand
Before it goes in the oven
- Air dried a full 24 hours
- No Prisme anywhere on this piece
- Oven cold, pot going in now
- 300 F, 35 minutes from temperature
- Window open, extractor running
- Oven off, door shut, cooling inside
- Nothing else in the oven with it
The ones that come up at the tables
Can these go in a kiln instead of an oven?
No. They cure at 300 F and burn away entirely long before a kiln reaches even bisque temperature. If you want color that gets fired, that is underglaze or, on a finished pot, an overglaze.
Can I use them inside the studio?
No. They are solvent based and they are not fired, so they belong on the outside tables along with the alcohol inks. The drying happens out there too.
Is a mug painted this way safe to drink from?
Only if the paint stayed off the rim and off the inside. The manufacturers do not call these food safe, which means they have not been tested for it rather than that they are known to be harmful. Either way, mask the rim before you start.
Why did my pot crack in the oven?
Almost certainly thermal shock. A cold glazed pot into a preheated oven, or a hot one pulled out into room air. Put it in cold, let it heat with the oven, then turn the oven off and let it cool inside with the door shut.
Can I bake Prisme to speed it up?
You can, and you should not. Heat turns it yellow and flattens the depth that made you buy it. Prisme air cures, it takes weeks rather than days to finish, and there is no shortcut.
How do these compare to underglaze?
Underglaze wins on permanence, on cost and on food safety, and it has to go on before the glaze firing. These win when the pot is already finished, when you want an effect no kiln produces, or when you want a color that cannot survive cone 5½.
Can I put them over a gold luster?
Better not to. Luster is an extremely thin metal film and baking a paint layer over it risks lifting it. Pick one finish for the piece rather than stacking them.
Is there a version that does not smell?
There is a water based version of the enamel colors. It is much milder, cleans up with water and bakes the same way, with a smaller color range and a slightly less glassy finish. It still gets used on the outside tables here.
Where to go next
Underglaze techniques, rules and firing
The fired alternative. Cheaper, permanent, food safe under a glaze, and it has to happen before the glaze firing.
Read it →How to use pottery overglazes
The other way to decorate a finished pot, except this one goes through a kiln and stays put.
Read it →Applying alcohol inks to pottery
The other unfired option on the outside tables. Faster, looser, and much less durable than these.
Read it →Food safe, dishwasher safe, what you can claim
Four words that mean four specific things, and the page to read before you describe a painted pot to anyone.
Read it →Using resists: wax, latex, tape and paper
Masking properly, which is what keeps the paint off the rim and the foot ring.
Read it →Clay Hole University
Every lesson in one place, from first day at the wheel through firing and glaze chemistry.
Start there →The right tool for a narrow job
These are not a replacement for glaze and they are not trying to be. What they are is the only way to put color on a pot that is already finished without a third firing, and the only way to get a honeycomb of cells onto a ceramic surface at all.
So know which of the three is in your hand, mask the rim, let it dry a full day, and put the pot into a cold oven. Get those four right and the rest of it is just painting.
Enamel and glass colors bake at 300 F in a cold-start oven after 24 hours of drying. Prisme air cures and never gets baked. None of it is food safe, and all of it happens on the outside tables.
If you want the three products in full, the Prisme detail and the eight ways it goes wrong, switch to the Comprehensive Version at the top of the page.
Which version would you like to print?
Videos come out as a labelled box with the title and channel to search for, since paper does not play them.