Archive for March, 2014

Repairing a Broken Bonsai Pot

I’ve been buying a lot of pots from Japan over the winter so I suppose it is inevitable that one would arrive broken (although it could have been prevented with better packing). Fortunately I didn’t pay a lot for it, but it is (was) still a valuable pot. Instead of tossing it, I took it as an opportunity to experiment with repairing ceramics. My goal is to make it usable which, in my climate, means it will need to stand up to constant moisture and freeze-thaw cycles. I love this style of pot and actually have the identical one in a smaller size, but it doesn’t have nearly as nice patina as this broken one.

You might be interested in the excellent articles and videos that Lakeside Pottery has on repairing ceramics. Some really great tips in there.

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Broken Keizan pot, 16.5″ x 12.5″ x 4″

After asking around and doing some research, the general consensus seems to be that epoxy is the best adhesive for repairing broken ceramics. I purchased some water-resistant marine epoxy for the job. An experienced potter and bonsai artist warned that epoxy will degrade after constant exposure to moisture, but more on how I tried to address that issue later.

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Water resistant two part epoxy.

After cleaning the broken pieces and doing a test fit (the order of assembly is important) I glued the pot back together in two stages. Excess epoxy that seeped out of the joints was wiped away with rubbing alcohol.

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The assembly was done in two stages, with the largest piece being glued on first, then the two smaller pieces the next day. The missing chips had been ground to dust during transit, so those areas were filled in with epoxy.

The goal was of course to get perfectly flush joints, but I found that  the quality of the joints decreased as more pieces were added. This is because as more pieces went in, the space taken up by the epoxy became incresaingly significant. This problem was magnified by the fact that there were so many joints. Removing some ceramic material from the joining surfaces might be a solution but could affect the final fit.

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One of the better joints.

I blended brown and grey acrylic paints to try and match the pot colour. I knew it wouldn’t be perfect since the patina on the old pot results in a gradient of colours. But it was an improvement on the glaring white epoxy. Many of you have probably heard of the approach of highlighting ceramic repairs with gold (kintsugi). I love this look but think it is most suitable for chips, single-line breaks, and older more valuable pots. The break on this pot is more of a “why didn’t you just throw it away?” kind of break.

Most damaged side of the pot, after touch up painting.

Most damaged side of the pot, after touch up painting.

To try and prolong the life of this repaired pot, the final step was to apply a heavy bead of waterproof marine grade silicone over the inside joints. The idea is that if I can waterproof the epoxy line that sees the most moisture, I may be able to keep it together longer (since I was warned that expoxy . Yes it looks ugly, but my goal is to make this pot usable and the inside of course will not be seen when the pot is in use.

Inside after applying silicone.

Inside after applying silicone.

Fortunately the pot still has an undamaged front which is presentable. Time will tell how well this repair will stand up to the elements. If you live in a cold weather climate and have tried a repair like this, I would really like to hear your experience.

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