Pottery made to order | repair and restoration studio in Southern Delaware

How to Repair a Crack in Broken Pottery?

How to Mend Hairline Cracks on Ceramic with Strong Mechanical Integrity?

When restoring ceramic vessels with hairline cracks, in particular when it has intricate painting and/or texture details, it is important not to completely break off the crack. We show two hairline crack mending possibilities: a) the "pegging" method or b) enabling the epoxy to flow and penetrate the crack (see video). Minimizing the repair surface area by not extending the break line length will reduce the repair cost, better preserve the value and integrity of the vessel, and with sound mechanical integrity.

Detecting a Hairline Crack in a Ceramic Vessel


The pegging technique ceramic repair can be used when you do not have the capability or the possibility of applying epoxy into the crack as shown in the above video. To effectively achieve pegging, the walls of the vessel need to be thick enough to accept a peg. Below, we repair a cracked jar with some step-by-step illustrations and explanation. To see examples of a cracked bowl, cracked mug, cracked plate, cracked vase, cracked urn, or a cracked jag, see our restoration examples page.

Choose to grind the groove on the side with less detail. In this example, we used a 5mm diamond rotary disk to create a groove across the crack to embed the peg. We also created a groove along the crack to allow the clear epoxy to pool so that it can penetrate through the crack's wall.
Broken jug - multiple breaks and a crack
Broken antique jug
The crack continue further than able to see
Long hairline crack
Dremel a channel accross and along the crack
Grind channel across and along crack

In this case, we used 12-gauge copper wire. We textured the surface to better bond with the adhesive. The razor blade is inserted in the crack to widen the gap for better epoxy penetration into the walls of the crack.
Copper wire is used a s apeg in this case
Gauge 12 copper wire in a vice
Grind wire's surface
Grind surface for better adhesion
Cut to size
Cut copper to size (peg)
Clean well
Clean surfaces with alcohol (91%)
Wedge a razor blade
Wedge a razor blade to widen crack
Try peg for proper fit
Shape peg and try for proper fit

Heating the mug and the epoxy to 120-140 degrees F will make the epoxy more liquid and enable it to penetrate through the crack. Warm the epoxy before mixing it and make sure the two parts do not touch each other to avoid cure time from starting (we use a microwave oven to warm epoxy). 120-140 degrees however, will reduce epoxy cure time from 5 minutes to about 2 minutes, so make sure all you need is near you.
Heat vessel
Heat mug for optimum epoxy cure
Heat epoxy
Warm epoxy to be thinner (microwave)
Mixing clear 2 part epoxy
Mix the warmed 2-part clear epoxy

Place the mug so that the crack and the grinded channels are on the bottom before placing the mixed 2-part epoxy. After applying the epoxy, inspect the other side of the crack to verify that the epoxy went through the walls of the crack. Remove the razor blade while the epoxy is still very liquid. Place the clamp before the epoxy hardens and put back in the oven (120-140 degrees F) for optimum cure strength.
Apply epoxy
Fill channel with epoxy
Remove razor blade
Remove razor blade
Clamp for tight fit
Clamp for better fit
Warm curing oven
Heat to 140 degree F for optimum cure
Mix epoxy filler
Mix filler epoxy
Apply epoxy filler
Fill gaps after removing excess epoxy

After cleaning the excess epoxy with a razor blade, fill all gaps with 2-part filler epoxy and sand with a Dremel and than by hand graduating to a very fine sandpaper.
Apply well
Push filler epoxy well in gaps
Sand surfaces
After curing over night, sand
Smooth surface
Peg areas sanded
Apply fine filler
Fill with finer epoxy filler
Fine sanding
Sand finer & finish sanding by hand
Mix colors to match skin and sleeve colors
Mix colors, paint and cold glaze How to paint repaired ceramic
Broken ceramic jug with hair crack restored
Lollypops jug restored - click for closeup
Cracked ceramic platter that needs repair
Another example of hair line crack in a Chinese ceramic platter

IMPORTANT: Ceramic restoration materials are not food-safe, liquid or heat proof (over 190 degrees F) and repaired items should not be used on cooking or food serving ware more...

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