Raku firing is a fast, active firing where glazed pots are taken out of the kiln at full heat and finished outside it, usually in a smoky reduction can. It is the step that gives raku its crackle lines, copper flashes and black clay. This guide walks through the whole process, the temperatures glaze makers publish, what goes in the reduction chamber, the main raku pottery firing techniques, and the gear that keeps you safe.
Home Pottery HQ is a research site. We have not run these firings ourselves; the figures come from glaze maker instructions, kiln maker spec sheets and published references listed under Sources.
What is raku firing?
In a normal glaze firing, pots heat for hours and cool for hours inside a closed kiln. Raku firing does the opposite: the kiln heats a few pots fast, the potter opens it while the glaze is molten, and the cooling happens outside the kiln, in open air, in water or in a lidded can of combustibles. That sudden change is what makes raku different from every other firing a home potter does. The name and the method trace back to 16th-century Japanese tea bowls; the smoky reduction step most Americans picture was added in the US in the 1960s, as our raku pottery guide explains.
Raku firing at a glance
| Stage | What happens | Typical time |
|---|---|---|
| Bisque firing | Pots are bisque fired in a regular kiln first | One normal bisque firing |
| Glazing | Raku glaze applied; Mayco calls for 2 to 3 coats | Let dry fully |
| Raku firing | Kiln heats until the glaze melts and smooths | About 20 minutes to 1 hour per load |
| Transfer | Pot lifted out with tongs into the reduction can | Seconds |
| Reduction | Lid closed; combustibles burn and smoke the pot | About 5 to 30 minutes; Mayco says about 20 |
| Cooling and cleaning | Pot cools, then is scrubbed | Until cool to the touch |
Before you fire: bisque, glaze and clay
Raku starts with bisqueware, not raw clay. Pots are bisque fired in a normal kiln so they are strong enough to handle and less likely to burst from trapped moisture. Our bisque firing guide covers that step.
Next comes the glaze. Use glazes sold for raku. Mayco's raku line calls for 2 to 3 coats on bisqueware (2 coats for two of its colors) and a full dry before firing. Leave the foot and the bottom unglazed so the pot can sit on the kiln shelf and be gripped with tongs.
The clay body matters because every pot goes through a violent temperature swing. A dense, tight body is more likely to crack. Our raku clay guide covers which bodies handle the thermal shock.
Raku firing temperatures
Raku is a low-fire process. Published figures cluster in a narrow band:
- Reference range: Western raku glaze firings typically run about 1,470°F to 1,830°F (800°C to 1,000°C).
- Mayco raku glazes: fire to cone 06, which Mayco lists as 1,850°F (1,010°C), and hold for 5 minutes.
- AMACO R-19 Copper Matte: listed for cone 06 to 04.
The two ranges differ by about 20°F (about 11°C) at the top end, which matters little in practice, because raku is judged by eye as much as by the pyrometer. Many potters watch the glaze through the spy hole: it bubbles as it melts, then settles to a smooth, glossy surface. That is the usual signal to shut off and pull. A pyrometer still helps you repeat results. For how cones relate to temperatures, see our pottery cone chart.
The raku firing process, step by step
This is an overview of a typical gas raku firing. Your kiln maker's manual comes first for lighting, burner settings and shutdown.
- Set up the site. Kiln on a noncombustible surface outdoors, reduction cans ready with a layer of combustibles, water bucket, hose and fire extinguisher within reach, and the path from kiln to can clear.
- Put on your gear before the burner is lit (see the PPE list below).
- Load the kiln with dry, glazed bisqueware, leaving room to get tongs around each pot.
- Light and fire following the maker's instructions. Warm up gently on the first load, since moisture in pots can cause cracking.
- Watch the glaze. When it has melted and smoothed (or the pyrometer reads your target), shut off the burner per the manual.
- Open the kiln by lifting the chamber or opening the walls, standing to the side and away from the heat.
- Lift the pot out with raku tongs and carry it straight to the reduction can.
- Close the lid once the combustibles flare, so the fire uses up the oxygen inside.
- Let it smoke and cool, then remove the pot with tongs or gloves.
- Clean it. Mayco suggests scrubbing the cooled pot with water and a scouring pad, which improves luster and color.
With a warm kiln, later loads often go faster than the first.
The reduction chamber
The reduction chamber is usually a metal can with a tight-fitting lid, such as a galvanized trash can, set on bare ground or gravel. It holds a bed of combustibles. The hot pot sets them alight, and the closed lid starves the fire of oxygen. That smoky, oxygen-poor atmosphere is what blackens bare clay, darkens crackle lines and pulls copper glazes toward metallic red and gold.
What to put in it
- Sawdust or wood shavings: steady smoke, good for dark crackle.
- Shredded newspaper or paper: fast flare-up, lighter smoke.
- Straw, hay, dry leaves or pine needles: uneven, patchy effects.
Stay with plain, untreated materials. Avoid painted or treated wood, plastics, glossy printed paper and anything with chemical coatings, which add toxic smoke.
Lid timing
Mayco says to put the lid on immediately and leave the pot about 20 minutes, until cool. Other guides cite about 5 minutes for small pots up to around 30 minutes for large ones. Short reduction tends to give lighter, more colorful copper; longer reduction gives deeper blacks.
Raku pottery firing techniques
Crackle raku
A white or clear crackle glaze crazes as the hot pot meets cool air. A few seconds of air before the can lets the crackle open up; smoke then fills the lines.
Copper matte
Copper glazes need heavy reduction. Some potters spray water or open the lid briefly near the end to flash colors. Results vary every firing, as AMACO's Copper Matte listing notes.
Horsehair
Bare, burnished pots skip the reduction can. Hair or feathers are laid on the hot clay just after it leaves the kiln and burn into fine lines. Work with long tweezers and gloves; the pot is still extremely hot.
Naked raku
A resist slip under a thin glaze layer cracks during firing and reduction. After cooling, the slip and glaze are peeled away, leaving smoke lines on the clay.
Water quench and air cooling
Some potters dip a pot in water after reduction to "freeze" the colors. This adds thermal shock, so expect more cracked pots. Air cooling with no can gives a bright, unsmoked surface.
For more on what each look means for the finished piece, including food safety, see our raku pottery guide.
PPE for raku firing
- Heat-resistant gloves: long-cuff gloves rated for high heat, such as Kevlar or heavy leather kiln gloves. See our kiln gloves guide.
- Face shield: a full face shield protects against radiant heat and flare-ups. Ceramic Arts Network also warns against staring into a red-hot kiln for long periods, since it can harm vision; IR-rated glasses help when you check the glaze.
- Respirator for smoke: a NIOSH-approved respirator with filters suited to smoke particles. A particle filter does not stop carbon monoxide, so stand upwind and keep your head out of the smoke column.
- Clothing: long sleeves and long pants in cotton, wool or denim; a leather welder's jacket or apron if you can. Synthetic fabrics can melt onto skin.
- Footwear: closed leather boots.
- Tongs: long raku tongs matched to your pot sizes. See our glaze tongs guide for the difference between dipping tongs and raku tongs.
Fire safety
Raku is an open-flame process with propane and burning combustibles. Fire only outdoors, as Mayco's instructions state for the reduction step, well away from buildings, fences, trees and dry vegetation. Check burn bans and your local fire code first. Keep a fire extinguisher, a charged hose and a water bucket within reach, and keep children and pets out of the area. Never open or insert tongs into an electric raku kiln without shutting it off.
A few more habits help:
- Assign one person to handle hot pots and keep everyone else out of the walking path.
- Keep spare combustibles in a closed metal bin, away from the kiln.
- After the last load, wet down the reduction cans and ash and check the site again before you leave it.
- Store raku glazes safely. Mayco labels all but one of its raku glazes CL (Health Caution) and not for children 12 and under.
Common raku firing mistakes
- Firing damp pots, which can crack or burst.
- Glazing the foot, so the pot sticks to the shelf or slips in the tongs.
- Too few combustibles, giving weak reduction and pale crackle.
- Lifting the lid early to check, which lets oxygen back in.
- Wearing synthetic clothing or short gloves.
What you need
A raku firing needs a kiln built to open hot, a reduction can, tongs and protective gear. Our raku kiln guide compares commercial gas and electric raku kilns from maker spec sheets, and our kiln gloves guide covers hand protection.
Sources: Mayco raku glaze product information (application, cone 06 firing and hold, removal, reduction time, cleaning, CL labels and safety instructions); Seattle Pottery Supply listing for AMACO R-19 Copper Matte; Wikipedia, Raku ware (Western firing range and history); The Pottery Wheel, What is Raku Pottery (firing and reduction time ranges, combustibles); Ceramic Arts Network, Tips for Successful Raku Firing (face shield, jacket and gloves, eye warning); Laguna Clay Heatwave Raku Kiln page. Specs checked October 2026.