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

How to Repair a Crack in Broken Pottery?




Repair Lessons
(click pictures)

Fixing broken plate lesson - basic lesson
Cementing only lesson
Fixing chipped Italian platter lesson step-by-step lesson
Chipped pottery repair lesson

Fixing broken vase - more complex repair
Restore vase lesson
How to Replace Stoneware Crock's rim using the potter's wheel
How to replace Stoneware crock's rim
Remove old repair, Mend the broken segments, fill gaps, sand filler, paint and glaze the repaired areas
Pottery and ceramic repair - all steps
kintsugi - mending broken pottery with gold
Kintsugi - mending with gold
Restoring multi breaks and missing piece antique bowl
Restore bowl lesson w/ missing pieces
Repairing broken stone sculptures and statues
Repairing broken stone sculpture
Restoring ceramic sculpture with missing pieces using fired clay
Making missing part w/ fired clay
How to paint broken china, ceramic or pottery?
Painting pottery after repair
Repairing broken plaster of paris tall lamp
Plaster lamp repair w/ missing parts
Restoring small porcealin figurines - shoe
Miniature Porcelain

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

We often receive valuable ceramic items and vessels with long hairline cracks and we need to decide if we should break the crack completely for a better cementing job. When the hairline crack goes through design details and breaking it will increase the required repair areas, we often use the "pegging" method illustrated below or the method shown in the video.


Detecting a Hairline Crack in a Ceramic Vessel


Pegging:

The pegging technique ceramic repair requires the walls of the vessel to be thick enough to accept a peg. When pegging is done properly, it is an excellent way to restore durability to the repaired ceramic object with a hairline crack prior to continuing the restoration process. 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 channels on the side with less details. In this example, we used a 5mm diamond rotary disk to create a channels across the crack to embed the peg. We also created a channel 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 for better bond with the adhesive. The razor blade is inserted in the crack to widen the gap for better epoxy penetration to 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 degree F will make the epoxy more liquid and enables 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 microwave oven to warm epoxy). 120-140 degrees however will reduce to 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 degree 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 sand paper.
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 degree F) and repaired items should not be used on cooking or food serving ware more...



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