Can You Fire Pottery Twice?
By Linda · · 7 min read
Yes. Firing pottery twice is the standard way ceramics are made. The first firing (bisque) hardens the raw clay at around cone 06–04, roughly 1,828–1,945°F (998–1,063°C). The second firing (glaze) melts the glaze onto the piece at anywhere from cone 06 up to cone 10, about 1,828–2,345°F (998–1,285°C) depending on your clay and glaze.
You can also fire a piece more than twice. Potters routinely refire to fix glaze flaws, add lusters or decals, or build up layered surfaces. Three, four, or more trips through the kiln are perfectly normal as long as you follow a few rules, which I’ll cover below.
Why is pottery fired twice?
Splitting the process into two firings solves two problems at once.
The bisque firing drives out all the chemically bound water and converts fragile greenware into hard, porous ceramic. That porosity matters: bisqueware soaks up glaze evenly, the way a sponge takes on water. If you’ve ever wondered what people mean by bisque, I explain the whole stage in my post on what bisque pottery is.
The glaze firing then melts the glaze coating into a glassy layer and matures the clay body to its final strength. Trying to do both jobs in one firing is possible (it’s called single firing or once-firing), but it’s riskier. Raw glaze on greenware flakes off easily during handling, and a wet glaze application can soften unfired clay enough to slump or crack.
Two firings also protect your kiln load. Greenware with trapped moisture can burst in the kiln and spray shards across every shelf. I’ve covered why pottery explodes in the kiln separately, and a slow bisque firing is the main defense.
Bisque firing vs. glaze firing at a glance
| Bisque firing (first) | Glaze firing (second) | |
|---|---|---|
| Purpose | Harden clay, burn out water and organics | Melt glaze, mature the clay body |
| Typical cone | Cone 06–04 | Cone 06–04 (low-fire), cone 5–6 (mid-fire), cone 9–10 (high-fire) |
| Temperature | 1,828–1,945°F (998–1,063°C) | 1,828–2,345°F (998–1,285°C) |
| Firing time | 8–10 hours, slow ramp | 6–12 hours depending on cone |
| Cooling time | 12–24 hours | 12–24 hours |
| Result | Hard, porous, unglazed ceramic | Vitrified, glass-coated finished piece |
Notice that the bisque firing is often cooler than the glaze firing, even though it comes first. That surprises beginners. The bisque only needs to get hot enough to make the clay permanent and porous; the glaze firing is what takes stoneware and porcelain up to full maturity. For more detail on target temperatures, see my guide to how hot a kiln needs to be for pottery.
How long does it take to fire pottery twice?
Plan on two to four days from loading the bisque to unloading the glaze firing, once you count cooling time.
- Bisque firing: 8–10 hours of firing, then 12–24 hours of cooling before you can unload.
- Glazing: an hour or so of work, plus drying time for the glaze.
- Glaze firing: 6–12 hours of firing, then another 12–24 hours of cooling.
The cooling is not optional. Opening a kiln above roughly 200°F (93°C) risks cracking your work from thermal shock. Quartz in the clay shrinks abruptly as it cools through 1,063°F (573°C), and pieces need to pass through that zone slowly. I break the full timeline down in how long pottery takes to fire.
Can you refire pottery that’s already been glazed?
Yes, and potters do it all the time. Common reasons to refire a finished piece:
- Fixing glaze defects. Pinholes, crawling, bare spots, or dry underfired glaze can often be corrected by touching up the glaze and firing again.
- Adding new layers. A second coat of glaze over the first can deepen color or fix a thin application.
- Decoration firings. Gold luster, mother-of-pearl, and ceramic decals go on over the fired glaze and get a separate low firing around cone 018–016, roughly 1,300–1,450°F (700–790°C).
The catch with reglazing a fired piece is that vitrified ceramic is no longer porous, so fresh glaze doesn’t want to stick. Warming the piece first (a kitchen oven at 300–350°F / 150–175°C works), spraying the glaze, or mixing in a little glue or spray starch all help it grip. I cover the techniques in detail in my post on whether you can reglaze pottery.
The golden rule of refiring: never go hotter
Once a piece has had its glaze firing, every firing after that should be at the same temperature as the glaze firing or cooler, ideally one to two cones cooler. (The glaze firing itself is usually hotter than the bisque; the rule kicks in after the glaze has matured.)
Refire hotter and you invite problems: the original glaze can re-melt and run off the pot onto your kiln shelf, colors can burn out (reds and pinks are especially fragile), and a clay body pushed past its maturity can bloat, warp, or slump. A typical sequence looks like this:
- Bisque at cone 04
- Glaze at cone 6
- Refire or touch-up at cone 6 or cooler
- Luster or decal firing at cone 018
After the glaze firing, each step holds steady or moves down the temperature scale. That’s the pattern to copy.
Can you bisque fire pottery twice?
Yes, and it’s a useful trick. Potters re-bisque when they:
- Apply underglaze decoration to bisqueware and want to set it before glazing, so brushwork doesn’t smear.
- Get a piece back from a too-cool bisque that’s still soft and chalky.
- Wash or rinse glaze off a piece to start over. The pot needs to dry completely and benefits from a fresh bisque before reglazing.
A second bisque firing doesn’t hurt the work. The only real cost is kiln time and electricity. If a piece went into the first bisque before it was fully dry and survived, a second bisque is also cheap insurance. Still, it’s better to avoid the problem up front, since pottery really can’t be too dry to fire, only too wet.
How many times can you fire a piece before it fails?
There’s no fixed limit, but each firing adds a small amount of stress. Some practical limits:
- Low-fire earthenware handles refiring well because the temperatures are gentler.
- Mid- and high-fire stoneware tolerates two or three glaze firings, but repeated trips to cone 6+ increase the odds of warping, dunting (cooling cracks), or glaze running.
- Already-flawed pieces (anything with a hairline crack) usually get worse with each refire, not better. Cracks open up; they don’t heal.
My rule of thumb: refire when there’s a specific fix or addition you’re after, not as a way to keep fiddling. If a piece needs a fourth firing to look right, the problem is usually in the glazing, not the kiln.
What can go wrong when firing twice (or more)?
- Glaze flaking before the firing. Thick or powdery raw glaze chips off when you load the kiln. Handle glazed ware by the foot.
- Shivering and crazing. Glaze and clay that shrink at different rates can pop off in flakes (shivering) or craze into fine cracks. Repeated firings can reveal a fit problem that one firing hid.
- Color shifts. Some glazes change noticeably on a refire — sometimes for the better, sometimes not. Test on a scrap piece if the pot matters to you.
- Stuck shelves. Refired glaze gets runnier than you expect. Use kiln wash and place refires on scrap shelf material or a cookie.
If you don’t have your own kiln, most studios that offer kiln rental will happily run a refire for you. See my post on where you can fire your pottery for what that typically costs.
FAQ
Can you fire pottery twice in a kiln?
Yes. Two firings, a bisque firing followed by a glaze firing, is the standard process for almost all kiln-fired ceramics. The bisque hardens the clay; the glaze firing melts the glassy coating.
Can you fire already-fired pottery again?
Yes. Glazed pottery can go back in the kiln to fix defects, add glaze layers, or apply lusters and decals. Refire at the same cone as the original glaze firing or cooler, never hotter.
Can you fire pottery twice without glaze?
Yes. A second bisque firing is common for setting underglaze decoration or finishing an underfired first bisque. Unglazed pieces can be fired repeatedly without issue.
Do you have to fire pottery twice?
No. Single firing (once-firing) takes greenware straight to glaze temperature with raw glaze applied. It saves time and fuel but carries a higher risk of glaze flaws and cracked work, so most potters stick with two firings.
How long do you wait between the first and second firing?
There’s no required wait. As soon as the bisqueware has cooled, you can glaze it and fire again, the same day if your kiln schedule allows. Just make sure the glaze coat is fully dry before the glaze firing, which usually takes a few hours.