Reglazing and Refiring: Rescuing a Bad Result
A disappointing pot is not a finished pot. Most glaze faults can be fired again, and a lot of them come back better than the original would have been. Here is what is worth rescuing, what is not, how to get glaze to stick to a glassy surface, and the two rules that keep a refire from making things worse.
You can refire almost anything. The hard part is getting new glaze to stick to a fired glassy surface, and the answer is heat the pot, thin the glaze, and build it in light coats. Crazing and a cracked pot are the two things a refire will not fix.
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The problem is that glass is not thirsty
Glazing bisque is easy because bisque is porous. It pulls the water out of the glaze on contact and the powder stays behind, stuck to the pot.
A fired pot has no porosity left. The glaze layer is glass. Brush wet glaze onto it and the water has nowhere to go, so it sits there, slides around, and falls off in sheets when it dries.
So every technique on this page is a way of solving that one problem: make the surface take the glaze, or make the glaze dry before it has a chance to run.
The route that works
Seven steps, applying a brushing glaze over an already fired surface.
- Decide it is worth it. A refire costs another firing slot and can still fail. Some pots are better let go.
- Clean the surface. Wash it, let it dry fully, then wipe with rubbing alcohol. Any grease and the glaze crawls off.
- Warm the pot. A hair dryer, a warm oven, or sunshine. Warm ceramic flashes the water out of the glaze and makes it grip instead of slide.
- Thin the glaze slightly and stir it well. Thick glaze on a glassy surface is the main reason this fails.
- Build it in light coats, drying between each. Three thin passes beat one thick one every time.
- Keep it off the foot by a generous margin. A refired glaze is more likely to run than the first coat was.
- Fire it to the same cone. Ours go back in at cone 5½ with everything else.
Three ways a refire goes wrong
The glaze slid straight off
Cold pot, thick glaze, or both. Wet glaze on non-porous glass has nothing to grip. Warm the pot, thin the glaze and build it in light coats.
It ran onto the shelf
Two layers of glaze means twice the flux and a much more fluid melt. A refired pot needs a wider clear margin at the foot than it did the first time, and a catch underneath is cheap insurance.
It came out blistered
The second firing reheated a glaze that had already released its gases, and the trapped bubbles had nowhere to go. Thinner coats and a slower climb help; some pots just will not take a third trip.
What is worth rescuing
Not every disappointing pot deserves a second firing. Being honest about this saves kiln space and saves you from a worse version of the same pot.
- Underfired, dry, rough glaze. The best candidate there is. It never melted properly, and a second trip often finishes the job with no new glaze at all.
- Too thin, patchy or starved. Another coat over the top usually fixes it outright, and this is the most common successful refire.
- A color you dislike. Entirely fixable. Glaze over it, and expect the result to be darker and deeper than the new glaze would be on its own.
- Bare spots and crawling. Worth a go. Clean carefully, because the cause was usually grease or dust that is still there.
- Pinholes. Often improved by a refire with a hold at the top, which gives the melt time to heal them. No new glaze needed.
- Somewhere between fine and disappointing. This is the honest one. A refire has a real failure rate, and a pot you are lukewarm about can come back worse. Sometimes the right call is to use it and make another.
The reframe worth having
A refire is not a repair that restores a pot to what you intended. It is a new firing with new variables that happens to start from a glazed pot. Treat it as another attempt rather than a correction and the results stop feeling like failures.
What a refire will not fix
Knowing the difference between a fault and a flaw saves a lot of wasted effort.
Crazing
The fine web of cracks is a mismatch between how much the glaze and the clay shrink as they cool. Another firing does not change either material, so the crazing comes straight back. The fix is a different glaze or a different clay, on the next pot.
A cracked pot
A crack in the clay body will not close. Heat opens it further, and a pot that survived one firing with a crack may come apart in the second. Not worth the shelf space or the risk to other work.
A warped form
Warping happened at temperature, when the pot was soft. Going back up does not straighten it and can make it worse, because the whole thing softens again with gravity still pulling.
S-cracks and structural faults
Anything that came from the making rather than the glazing. A second firing only ever addresses the surface.
Bloating
Blisters in the clay body itself, from overfiring or from impurities gassing. Refiring makes it worse, every time.
A shape you do not like
Obvious when written down and surprisingly common as a hope. No amount of glaze rescues a form. Make another one; you are better at it now than you were then.
Getting glaze to stick to glass
This is the whole technical content of reglazing. Everything else is ordinary glazing.
- Warm the pot. This is the big one. A pot at 120 to 150 F flashes the water out of the glaze on contact, which is the porosity you no longer have. A hair dryer, a low oven, or a sunny windowsill. Warm, not hot enough to burn your hands.
- Clean it properly first. Wash, dry completely, then wipe with rubbing alcohol. Skin oil is the reason most reglazed pots crawl.
- Thin the glaze a little. Slightly thinner than you would use on bisque, because a thick layer on glass has nothing holding it up.
- Build it in light coats. Three thin passes with drying between them will stay put where one heavy pass slides off in a sheet.
- Brushing glazes are far easier than dipping. They carry gums that help them grip, which is exactly the problem you are solving. Dipping a fired pot mostly does not work.
- Sanding or scratching the surface helps a little. A quick pass with coarse paper gives the glaze some tooth. Do it wet, and it is optional rather than essential.
- Gum or a glaze binder is the last resort if a particular glaze refuses to stay. A few drops of CMC gum in the batch makes it much stickier.
Step by step
- Work out what went wrong first. Underfired, too thin, crawled, pinholed. The fault decides whether you add glaze or just fire it again.
- Wash and dry the pot, then wipe it down with rubbing alcohol and stop touching the surface you are about to glaze.
- Warm it through. Not just the surface. A pot warmed for a few minutes in a low oven holds the heat long enough to glaze the whole thing.
- Stir and thin the glaze, then work quickly while the pot is still warm.
- Apply light coats, letting each flash off before the next. If a coat starts sliding, stop, let it dry, and come back.
- Leave a wider margin at the foot than you normally would. At least a quarter inch more.
- Let it dry slowly and completely before firing. Anything still damp under a sealed layer causes trouble.
- Send it in with a note about what it is, so it can be loaded on a shelf where a run will not damage anyone else's work.
The firing itself
A refire is mostly an ordinary glaze firing with a pot in it that has already been through one.
- Same cone as the original. Ours go back to cone 5½ with everything else. Firing hotter to force a melt is how a rescue turns into a run.
- A slower climb helps, especially for pinholes and blisters, because it gives gases time to leave before the glaze seals over.
- The hold matters more than usual. Time at temperature lets a reluctant melt finish and heal its own faults.
- Expect the color to deepen. Two layers of glaze read darker and often more interesting than either alone. This is a feature more often than a problem.
- The glaze underneath melts again too. You are not adding a layer on top of a stable surface; you are melting both together. That is why the result is genuinely new rather than a patch.
- Diminishing returns after the second or third trip. Each firing is more heatwork on the clay body, and eventually the body starts to suffer before the glaze improves.
The risks of a refire
A refire is not free and it is not certain. Both of those matter in a shared studio, where a run affects more than your own pot.
- Running is the big one. Two glaze layers melt more fluidly than one. A glaze that behaved perfectly the first time can move on the second, and a run reaches the shelf, the kiln furniture and sometimes a neighbor's work.
- Blistering. Reheating a glaze that already released its gases can trap bubbles that never heal.
- The pot can crack. Every firing is thermal stress. A pot with a flaw you cannot see may not survive a second one.
- It might come back worse. Genuinely. A mediocre pot can turn into an unusable one, and that outcome is common enough to be worth weighing.
- It costs a firing. Kiln space, time and energy, for a pot that already exists.
The one rule that prevents most damage
Leave more clearance at the foot than you think you need, and assume the glaze will move. That single habit is the difference between a refire that fails quietly and one that welds a pot to a shelf.
How it works here
Refires go through the same glaze firings as everything else, at cone 5½. There is no separate refire kiln and no special schedule.
- Tell somebody it is a refire when you put it on the shelf. It changes where it gets loaded, and that protects other people's work as much as yours.
- Expect a wide foot margin to be checked. Anything with glaze close to the foot may come back to you rather than going in.
- Firing is charged the same way as any other piece. A refire is a firing, so it is measured and billed like one.
- A piece that runs onto a shelf means a damaged shelf, and shelves are not cheap. This is the reason for the caution rather than an arbitrary rule.
- If you are not sure whether it is worth refiring, ask. Somebody here has almost certainly tried the same rescue on the same glaze.
What goes wrong, and what caused it
The glaze slid off while you were applying it
Cold pot. Warm it through and work while it is still warm. This is the single most common reason people conclude that reglazing does not work.
It dried and then flaked off in sheets
Too thick. On a non-porous surface a heavy layer shrinks as it dries and has nothing gripping it. Thinner glaze, lighter coats.
Bare patches after firing
Crawling, from grease or dust on the surface. Clean with alcohol and then do not touch the area with bare hands.
It ran and stuck to the shelf
Two layers of flux, a more fluid melt, and not enough clearance. This is the failure that costs somebody money, which is why the margin rule exists.
Blisters and craters that were not there before
Gases trapped under a glaze that had already sealed. A slower climb and a hold help. Some pots simply will not take a second trip.
The crazing came back
It was always going to. Crazing is a fit problem between glaze and clay, and refiring changes neither. Take that one as information for the next pot.
The ones that come up at the tables
Can you refire already glazed pottery?
Yes, and it works far more often than people expect. The difficulty is not the firing, it is getting new glaze to stay on a non-porous fired surface. Warm the pot, thin the glaze, and build it in light coats.
How many times can a pot be fired?
There is no hard limit, and returns diminish. Each firing is more heatwork on the clay body and more thermal stress. Two or three glaze firings is common; beyond that the body often starts to suffer before the surface improves.
Will a refire fix crazing?
No. Crazing is a mismatch between how much the glaze and the clay contract as they cool, and refiring changes neither material. It will craze again. The fix belongs to the next pot: a different glaze, a different clay, or more silica in the recipe.
Do I have to add new glaze?
Not always. An underfired glaze often just needs more heatwork, and pinholes frequently heal with a second firing and a hold at the top. If the original glaze is simply too thin or the wrong color, then yes, new glaze goes on.
Why does my glaze slide off a fired pot?
Because there is no porosity left to pull the water out. On bisque the pot drinks the water and the glaze grips instantly. On a fired surface it sits on top. Warming the pot to around 120 to 150 F flashes the water off and solves most of it.
Can I dip a fired pot instead of brushing?
Mostly not. Dipping relies on the pot absorbing water instantly, which a fired pot cannot do, so the glaze runs straight back off. Brushing glazes carry gums that help them grip, which is why they are the right tool here.
Will the color be the same as the new glaze?
No, and that is worth planning for. You are melting two glazes together, so the result is usually darker and more complex than the new glaze alone. Many people end up preferring it, but do not expect the swatch.
Is a refired pot still food safe?
It can be, judged the same way as any other pot. The surface has to be fully melted, smooth and not crazed. A refire that finally melts an underfired glaze has made it more food safe, not less. A refire that left blisters or bare patches has not.
Where to go next
What pottery glaze actually is
Why a fired surface is glass, why that makes reglazing hard, and what each fault is telling you.
Read it →Glaze problems, causes and fixes
Diagnose the fault before you decide on the rescue. Crawling, pinholes, blisters and running in detail.
Read it →Glaze brushing techniques
Brushing is the method that works on a fired pot, so it is worth being good at it.
Read it →How to use pottery overglazes
The other reason a finished pot goes back in a kiln, at a much lower temperature.
Read it →Clay Hole University
Every lesson and guide in one place, from first day at the wheel through firing and glaze chemistry.
Start there →The kiln is not the last word
Opening a kiln to a pot that did not work is one of the genuinely deflating experiences in this craft, partly because it arrives weeks after the making, when you have already decided how you feel about the piece.
Knowing that a second firing is available changes that. Not because everything can be saved, but because the verdict stops being final. Warm the pot, thin the glaze, leave room at the foot, and accept that some of them will come back worse. The ones that come back better are usually more interesting than what you originally had in mind.
Refiring works. Warm the pot, thin the glaze, light coats, wide margin at the foot, same cone. Crazing, cracks and warping are not fixable, and two glaze layers run more easily than one.
If you want the full triage list, the sticking techniques and the eight ways it goes wrong, switch to the Comprehensive Version at the top of the page.
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