Repairing broken ceramics and glass: conservators, kintsugi and what is food safe

A favourite mug slips off the draining board. A bowl from a potter you visited years ago lands on the tiles. The first instinct is to reach for the glue. It is worth pausing, because what you do in the first hour decides which repairs are still possible.

There are three broad routes: a professional conservator, traditional kintsugi with urushi lacquer, and a quick repair with a resin kit. They differ in cost, time and appearance, and above all in whether you can eat or drink from the piece afterwards.

This guide sets out the options using conservation bodies, museum sources and kintsugi practitioners' own guidance. It covers ceramics first, then glass, which has its own limits.

Key takeaways

• Keep every fragment, including small chips, and do not glue anything until you have chosen a route.
• Decide whether the repaired piece is for display or for use. Most repair materials change the answer.
• Claims about resin-based "kintsugi kits" conflict: some are sold as decorative only, others as food safe. Tsugu Tsugu, a Tokyo kintsugi studio, says modern kintsugi with fast-drying resins is not food safe.
• Traditional kintsugi uses urushi lacquer, can cause skin reactions until fully cured and commonly takes two to three months.
• Even after a careful repair, makers advise hand washing and keeping repaired pieces out of the microwave, dishwasher and oven.
• In the UK, find a conservator through Icon's Conservation Register. In Poland, ask the conservation sections of the Polish Artists' Union (ZPAP) or the conservation departments of fine arts academies.

First steps after a break

• Collect everything. Small chips fill gaps that would otherwise need modelling.
• Wrap pieces separately in soft paper so broken edges do not grind against each other.
• Do not wash or glue. The Canadian Conservation Institute (CCI) notes that old adhesives can yellow, discolour or lose strength, and that removing them is part of a conservator's work.
• Note what you know about the piece: maker, date, clay or glass type, and any earlier repairs.

Option 1: a conservator

A conservator repairs an object to stabilise it and preserve its character, and records what was done. Icon, the UK's Institute of Conservation, publishes guidance on selecting a conservator. Its steps include outlining your requirements, contacting conservators with relevant experience, letting the conservator see the object before preparing a treatment proposal and quotation, checking security and insurance, agreeing a written contract with timeframes, and receiving a final project report on completion.

Icon also notes:

• the treatment proposal should come in writing with the estimate, and you should be consulted before it changes;
• it is usual to pay a deposit, with further payments at stages or on completion;
• conservators can advise on significance, but for a valuation you need an auction house or a valuer;
• a final report, with photographs, should be kept with the object.

Conservation repairs are generally made for display. CCI notes that old repairs can include adhesive residues, staples or rivets and fills, that metal staples can corrode and stain, and that relative humidity above 75% can weaken adhesives. A conservator will tell you whether a repaired piece can be handled or used, and how.

Option 2: traditional kintsugi with urushi

Kintsugi is the Japanese practice of mending ceramics with lacquer and finishing the seams with gold or other metal powder. A well-known story places its origin in the 15th century. The New Orleans Museum of Art tells it this way: the shogun Ashikaga Yoshimasa's favourite Chinese bowl broke and came back mended with metal staples, and his dissatisfaction is said to have prompted craftsmen to find a more beautiful method using layers of tree-sap lacquer finished with gold dust. The museum presents it as a story ("is said to begin"). A bowl usually linked to this tradition, a 13th-century Chinese Longquan celadon bowl named Bakōhan, is held by the Tokyo National Museum as an Important Cultural Property. The Metropolitan Museum of Art describes kintsugi as a technique unique to Japan and notes that in China broken ceramics were typically mended with metal staples. Tsugu Tsugu estimates that kintsugi became popular during the Muromachi period, linked to tea culture. Treat the Yoshimasa story as tradition rather than documented fact.

Kintsugi repairs appear in museum collections. Amgueddfa Cymru, Museum Wales, holds an early 18th-century Japanese vase recorded as having been damaged and repaired with gold lacquer kintsugi.

What to know before choosing it:

• It is slow. Tsugu Tsugu says one layer takes a few days to a week to dry and a full restoration very commonly takes two to three months, cured at around 20 to 25 °C and 70 to 80% humidity.
• Raw urushi can cause skin reactions. Tsugu Tsugu strongly recommends gloves and covered arms, and says cured lacquer does not cause allergic reactions.
• Use is limited. Tsugu Tsugu gives a heat resistance of about 95 °C for cured urushi, says to wait at least a month before regular use, to wash by hand, and never to put a kintsugi piece in a microwave, dishwasher, oven or open flame.

You can learn to do it yourself with an urushi kit and patience, or commission a kintsugi practitioner.

Option 3: resin kits sold as "kintsugi"

Many kits sold as kintsugi replace urushi with synthetic resins and a gold-coloured powder. They are much quicker than urushi and the look can be striking. The trade-off is food use. Tsugu Tsugu says modern kintsugi with fast-drying chemical resins is not food safe and should be used for decoration. Mud Australia, which suggests kintsugi as an alternative to discarding broken porcelain, says such pieces cannot be used for serving, eating or drinking.

Retailer listings disagree, sometimes about kits from the same brand, and we found no kit maker's technical data sheet naming the food contact rules its resin meets. If a kit claims food safety, look for the manufacturer's own technical data sheet stating which food contact rules it meets and under which conditions, and treat retailer listings with caution. When in doubt, use the repaired piece for display, dry goods or plants.

Glass: what can and cannot be done

Glass is harder to repair invisibly. CCI notes that breaks in glass are very visible, that stable adhesives with minimal yellowing are preferred, and that light and UV can discolour adhesives over time. It also describes "crizzling" and "weeping", a deterioration of unstable historic glass, and recommends keeping such glass at around 40 to 50% relative humidity and never below 30%.

Practical points for owners:

• Everyday drinking glasses with cracks or chips at the rim are usually best replaced rather than repaired for use.
• Valued or historic glass can be stabilised and joined by a conservator for display.
• Stained glass is a specialism of its own. In the UK the British Society of Master Glass Painters lists members who are Accredited Conservator-Restorers, by region, and advises collecting all fragments after damage because even small pieces help.

Finding a conservator

United Kingdom. Icon's Conservation Register is a free online directory of Icon-Accredited conservators. Icon says you can search by object, specialism or material, or by name to confirm someone's status, and that conservators who do not appear on the Register at all are not Accredited. Accredited members are peer-assessed and take part in continuing professional development reviews.

Poland. There is no single public register like Icon's. Places to start:

• the Conservation of Works of Art Section of the Warsaw district of the Polish Artists' Union (Sekcja Konserwacji Dzieł Sztuki OW ZPAP), which runs the annual "Sztuka Konserwacji" meetings with the Polish Chamber of Artist-Conservators of Works of Art;
• academies with ceramics and glass conservation programmes, such as the Academy of Fine Arts in Wrocław, which teaches conservation and restoration of ceramics and glass as a six-year degree.

Wherever you are, ask for a written proposal and estimate, a contract with dates and a final report with photographs, as Icon recommends.

Questions to ask before any repair

Whoever does the work, these questions help you compare options and avoid surprises:

• Display or use? Say clearly whether you want to eat or drink from the piece again, and ask what that rules out.
• What materials will you use? Urushi, a conservation adhesive or a synthetic resin each behave differently with heat, water and time.
• Will the repair show? Kintsugi makes the break part of the look. A conservator may aim for a discreet join or a visible one, depending on the object.
• What happens to missing pieces? Ask how gaps will be filled and whether the fill will match.
• How long and how much? Ask for a written estimate and timeframe, as Icon recommends.
• What record will I get? Photographs before and after, materials used and care advice.

If the piece came from a living maker, ask them too. Some makers will advise on a repair, or may be able to make a replacement.

Keep the repair record

Whatever route you choose, keep the report, the conservator's or practitioner's name, the materials used and photographs before and after. If the piece is ever sold, insured or repaired again, that record matters. Our guide to provenance records for handmade objects explains what to keep.

Sources

• Selecting a conservator, Icon: steps, written proposal and estimate, deposit, valuations, contracts, final report
• A new way to find conservators you can trust, Icon: Conservation Register, free, search options, accreditation and CPD
• Find a conservator, Icon: directory of Accredited members, filters by specialism and location
• Caring for ceramic and glass objects, Canadian Conservation Institute: old repairs, adhesives yellowing and failing, staples corroding, humidity above 75%, glass breaks visible, crizzling and humidity ranges
• Kintsugi reflects beauty in flaws, strength in healing, New Orleans Museum of Art: Yoshimasa story presented as tradition, lacquer and gold dust
• Bowl with a foliate rim, named "Bakōhan", Tokyo National Museum (ColBase): Longquan celadon, Southern Song, 13th century, Important Cultural Property
• Tea bowl, 16.122.5, The Metropolitan Museum of Art: kintsugi unique to Japan, metal staples typical in China
• Vase with kintsugi repairs, Amgueddfa Cymru, Museum Wales: early 18th-century Japanese vase with gold lacquer repairs
• The history of kintsugi, Tsugu Tsugu: Muromachi estimate, tea culture, modern resin kintsugi not food safe
• 3 steps to start kintsugi at home, Tsugu Tsugu: gloves, drying times, 2 to 3 months, humidity, 95 °C heat resistance, no microwave or dishwasher, one month before use
• Caring for your ceramic pieces, Mud Australia: kintsugi-repaired pieces are decorative only, discarding damaged pieces
• Find a conservator, British Society of Master Glass Painters: regional list of members who are Accredited Conservator-Restorers, collecting fragments
• Sekcja Konserwacji Dzieł Sztuki OW ZPAP: conservation section, "Sztuka Konserwacji" meetings, co-organisers
• Akademia Sztuk Pięknych we Wrocławiu, wroclaw.pl: six-year conservation and restoration of ceramics and glass programme