Ⅰ. Repair Suitability and Special Considerations
The appropriate kintsugi repair method varies depending on the material, form, condition of the damage, and intended use of each piece. During the assessment, we will discuss these factors carefully and determine the most suitable repair approach.
The examples below include cases that require more detailed consultation before the repair method can be confirmed, as well as items that may not be suitable for kintsugi repair.
1. Display Pieces
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For pieces intended only for display, the main consideration is whether the repaired joint can safely support the weight of the broken section. When the bonding surface is very small or thin, or when the repaired section projects outward from the main body, additional reinforcement may be required.
Points to consider:
・The size and thickness of the bonding surface
・The weight of the broken section
・The direction in which gravity acts on the repair
・Whether the piece will be moved or handled regularly
・Whether additional reinforcement is required
・How visible the reinforcement may be
Depending on the material and the condition of the damage, some pieces may not be suitable for repair. Please begin by booking either an online assessment or an in-studio assessment.
2. Practical Pieces
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Some practical pieces require modifications to the standard kintsugi process in order to achieve the most suitable balance of durability, appearance, and intended use.
【Parts Subjected to Continuous Stress】
Example: Cup Handles
Repaired handles are subjected to repeated bending and shear forces during normal use. Depending on how you intend to use the piece, there are three repair options:
1. Remove the Handle
The entire handle is removed. The cup is then used by holding the body directly.
2. Standard Kintsugi Repair
The handle is simply reattached. To reduce stress on the repair, the cup should be held by the body rather than by the handle.
3. Reinforced Repair
The handle is reattached and internally reinforced. This is suitable for practical everyday use, allowing the cup to be used in the same way as before the damage.
Other examples that may require reinforcement include cake stand columns, thin wine glass stems, and other parts that continuously support weight or experience repeated stress during normal use.
【Pieces Exposed to Hot Steam】
Example: Teapot Lids
Hot steam gradually weakens urushi adhesive. Depending on how you intend to use the teapot, there are two repair options:
1. Standard Kintsugi
The repair line on the interior surface, where steam is concentrated, is made slightly wider to provide additional protection. This repair is suitable for use with water up to 80°C.
2. Fully Coated Interior
The entire inside surface of the lid is coated with urushi, creating additional protection against steam. You may choose the colour of the urushi finish. This repair is suitable for use with water up to 90°C.
【Pieces Intended to Hold Water Continuously】
Example: Flower Vases
Kintsugi is suitable when the repaired area remains above the water line. However, urushi should not be used on areas that remain continuously submerged.
Since flower vases do not require a food-safe repair, the submerged areas are repaired using an appropriate synthetic adhesive. The exterior is then finished with urushi and decorated with gold, preserving the appearance of a traditional kintsugi repair.
【Glass Pieces】
Dense, Non-Porous Surface
Glass has a dense, non-porous surface, and urushi does not bond to it as readily as it does to porous ceramics. For this reason, thin or delicate glass pieces may require additional reinforcement depending on the location and nature of the damage.
Transparency of Glass
Once cured, urushi becomes a dark brown colour. Although the repaired surface is covered with gold, the adhesive itself can still be visible through transparent glass.
To prevent the colour of the urushi from showing through, the broken surfaces are first covered with gold before the pieces are bonded together with urushi. This allows the finished repair to maintain the appearance of traditional kintsugi while preventing the dark adhesive from being visible through the glass.
Ⅱ. Items We Cannot Accept for Kintsugi Repair
Kintsugi is not suitable for every material or intended use. Depending on the properties of the material, the temperatures involved during use, and the condition of the damage, a safe and durable urushi repair may not be possible.
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As a general rule, we cannot accept items that fall into the following categories.
【Items Used over Direct Heat or at High Temperatures】
Urushi cannot withstand direct flame or the high temperatures produced by cooking appliances. For this reason, repaired items cannot be returned to their original heating use.
Examples include:
・Donabe and other clay pots used over direct heat
・Heat-resistant ceramics used over direct heat
・Dishes used in ovens or toaster ovens
・Utensils or vessels exposed directly to charcoal or flame
In some cases, these items may be repaired for display purposes, but they cannot be used again for heating or cooking.
【Flexible Materials】
Once cured, urushi forms a rigid adhesive layer and surface coating. It is therefore unsuitable for materials that repeatedly bend, stretch, compress, or otherwise change shape during use.
Examples include:
・Silicone products
・Rubber products
・Soft vinyl products
・Flexible plastic items that are bent or compressed during use
Each time the material flexes, stress is concentrated along the boundary between the material and the cured urushi, making it impossible to maintain a durable bond or coating.
【Plastics to Which Urushi Does Not Bond Reliably】
Certain plastics have surfaces to which urushi does not adhere reliably and therefore cannot be joined using traditional kintsugi methods.
Examples include:
・Polyethylene (PE)
・Polypropylene (PP)
・Fluoropolymers such as PTFE or Teflon-type materials
・Items with silicone coatings or highly water-repellent surface treatments
This does not mean that all plastic items are unsuitable for repair. When the material is unknown, suitability must be assessed individually.
【Severely Deteriorated Materials】
A repair cannot be made durable when the material itself continues to crumble or separate, even if the urushi adheres to the immediate bonding surface.
Examples include:
・Bonding surfaces that crumble into powder
・Materials whose surface or body continues to delaminate
・Items that have become brittle throughout
・Materials that have lost their structural strength through moisture damage or age
In these cases, the item may fail again in the surrounding material rather than along the repaired joint.
Ⅲ. Potential Risks During the Repair Process
Each piece presents a different combination of materials, surface finishes, condition, and repair history. Kintsugica carefully assesses these factors and selects the most appropriate repair method. However, some risks cannot be eliminated entirely, including staining, surface alteration, damage to fragile areas, and changes in shape or alignment.
1. Unintended Staining and Urushi Penetration
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Once cured, urushi becomes a dark brown colour. Before beginning the repair, we assess the material, glaze, surface condition, and other relevant characteristics of the piece. Preventive measures such as masking and sealing are used when necessary, but unintended staining or penetration cannot always be prevented completely.
Urushi staining is more likely to remain in the following areas:
- Matte, textured, or porous glazes
Urushi may enter microscopic pores and surface irregularities, making it difficult to remove completely. - Unglazed surfaces and foot rings
Urushi may enter microscopic pores, rough surfaces, and irregularities, leaving dark brown staining that cannot always be removed completely. - Broken edges, chips, pinholes, and areas of glaze loss
Urushi may penetrate the exposed ceramic body and cause staining around the affected area. If the glaze is thin, pale, or translucent, the staining may also remain visible through the glaze. - Crazing and fine cracks in the glaze
If urushi reaches the opening of a crack, capillary action may draw it further inside, causing dark staining along the crack.
When urushi enters microscopic pores or penetrates the ceramic body, it may spread beyond the area visible from the surface and may not be fully removable.
2. Damage to Decoration and Printed Surfaces
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Decorative finishes may be considerably more fragile than the underlying ceramic surface. Gold or silver decoration, overglaze painting, decals, transfer prints, sublimation printing, surface coatings, and hand-painted details may be affected during cleaning, masking, removal of excess urushi, polishing, or general handling.
Some decorative materials may dissolve, soften, fade, or transfer when exposed to water or cleaning solvents. Others may be scratched, worn away, lifted, or peeled by friction or masking materials.
We assess the condition of the decoration and take appropriate preventive measures before beginning the repair. However, the composition and stability of a decorative finish may not always be identifiable, and existing deterioration may not be visible. For this reason, unintended changes or loss cannot be prevented completely, particularly when the decoration is already worn, loose, cracked, or flaking.
3. Changes to Surface Appearance, Gloss, and Texture
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Cleaning, masking, removing excess urushi, and polishing may alter the appearance, gloss, or texture of the surrounding surface. Matte areas may become smoother or shinier, while glossy surfaces may become duller or develop fine marks. Masking materials may also leave adhesive residue or visible boundaries on sensitive, porous, or textured surfaces.
Surface characteristics developed through age and use may also be affected. Natural patina, accumulated staining, and tea stains intentionally preserved or developed through continued use may be reduced or removed where cleaning or other treatment is required.
We assess each surface carefully, select methods appropriate to its condition, and limit treatment to the necessary areas. However, changes in gloss, texture, colour, or established surface character cannot always be prevented completely.
4. Minor Loss from Fragile or Weakened Areas
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Broken edges, exposed ceramic bodies, weakened glaze, and previously damaged areas may be extremely fragile. During cleaning, test fitting, bonding, masking, or handling, small particles or flakes may detach from these areas.
Existing weakness is not always visible before treatment. Fine cracks, loose glaze, powdering ceramic bodies, or partially detached fragments may become apparent only after the repair process has begun.
We handle each piece carefully and take appropriate preventive measures, but minor loss from already fragile or weakened areas cannot always be prevented completely.
5. Expansion of Existing Cracks or Hidden Damage
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Existing cracks, internal fractures, and weakened areas may extend during cleaning, test fitting, bonding, securing, or handling. In some cases, hidden damage may only become visible after treatment has begun, or an apparently stable section may separate along an existing fracture.
We assess the condition of each piece and handle it with appropriate care. However, the full extent of internal or pre-existing damage cannot always be identified in advance, and its progression cannot always be prevented completely.
6. Risks Associated with Removing Previous Repairs
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Previous repairs may include adhesives, fillers, paint, tape residue, metal staples, or other materials that must be removed before kintsugi repair can begin. These materials may have penetrated the ceramic body, bonded to fragile surfaces, or become embedded in cracks and pores.
During removal, small areas of ceramic, glaze, decoration, or existing surface deposits may also be lost or altered. Patina, accumulated staining, and tea stains developed through long use may be reduced or removed together with the previous repair material. In some cases, complete removal is not possible without causing further damage.
We assess each previous repair carefully and remove only what is necessary. However, unintended loss, staining, or surface change cannot always be prevented completely.
7. Residue of Metal Powders and Other Fine Particles
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Metal powders, polishing residues, charcoal powder from polishing charcoal, and other fine particles may enter microscopic pores, pinholes, crazing, textured glazes, unglazed surfaces, or existing scratches during the repair process.
Once embedded, these particles may be difficult or impossible to remove completely and may remain visible as dark or metallic specks. We use masking and careful cleaning to reduce this risk, but complete removal cannot always be guaranteed.
Ⅳ. Limitations of the Finished Repair
1. Changes in Shape, Alignment, and Surface Level
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A thin adhesive layer remains between joined fragments, and small amounts of the original material may have been lost or compressed at the broken edges. As a result, the repaired piece may not return exactly to its original shape or dimensions.
Slight steps, unevenness, or changes in alignment may remain along the repaired joints. In pieces broken into several fragments, small differences at each joint may accumulate, causing minor distortion, uneven rim height, or changes in the overall form.
We align each fragment as accurately as possible, but complete continuity of shape and surface level cannot always be restored.
2. Differences in Reconstructed or Filled Areas
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When part of the original material is missing, the area must be reconstructed using urushi-based filling materials. Its original shape may need to be estimated from the surrounding form, particularly when no reference fragment or photograph is available.
Reconstructed areas may differ slightly from the original in shape, thickness, curvature, surface level, or texture. Fine moulded details, irregular contours, glaze characteristics, translucency, and decorative patterns may not be reproduced exactly.
We shape and finish each filled area as accurately as possible, but some visible or tactile difference between the reconstructed section and the original material may remain.
3. Variations in Colour, Gloss, and Finish
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Urushi and metal powders are natural materials, and their final appearance may vary according to the material, application thickness, curing conditions, polishing, and the surface beneath them.
The colour and gloss of the repaired lines may not be completely uniform. Gold, silver, and other metal finishes may also differ slightly in tone, brightness, texture, or reflectivity between different areas of the same repair or from reference images and samples.
We aim for a consistent and appropriate finish, but exact uniformity in colour, gloss, and surface appearance cannot always be achieved.