What a Crack Pot!

Really, this pot is cracked!  In this post I will show how I repaired simple cracks on this Chinese Antique pot.  The repair isn’t permanent but will last for many years.  I will also talk about how to distinguish the difference between a crack made during the life of the pot and surface cracks that occurred during the firing process. Perhaps you have some cracked pots in your own collection that you can try fixing or perhaps it turns out they weren’t really cracks at all.

How do you know a pot is cracked?

There are several ways to find out if a pot is cracked.  The first thing I always do is hold the pot with one hand and tap it on several points with the knuckle of my other hand.  The sound that you get should be a somewhat high pitch resonating sound.  The harder the clay, the higher the pitch of the resonating sound.  If the sound is a dud sound with no resonance, then there is a crack somewhere.  The second thing I do is a thorough visual inspection of the pot.  With a good visual inspection, you can find small chips or even repairs to the pot that the sound check will not detect.  Once a cracked pot is repaired, the pot will produce a resonating sound when tapped.

Here are some obvious chips on a pot that will be found on a good visual inspection.  The important part is finding out if these are just chips or do they lead to more severe cracks.

The best way to train your eyes and ears is to go through your own collection and practice.  Get use to what the resonating sound sounds like because it’s slightly different from pot to pot.  Then thoroughly inspect the pots and try to find all the small imperfections on them.  You may be surprised at what you find.  With enough practice, the chances that you buy a pot that is cracked or have unknown imperfections will drop dramatically.  It’s always a bummer when you take a pot home and find out it’s cracked.

Why are cracks important to identify?

1. Value – The value of a pot will always go down if it’s cracked, damaged or have been repaired.  Depending on what kind of pot it is, the value may drop slightly or sometimes become worthless.  Mr. Tanaka says the great thing about a pot is that even if it is cracked or have been repaired, it can still be used in Bonsai.  Sometimes good pots that have cracks on them can still retain a very high value.

This is not a crack but you can see that a corner of the pot broke off a long time ago and it was filled in with a soft metal.  This Antique Chinese pot retails at about 3500 dollars, but because of the fix, the value has dropped to 3000 dollars.  Not bad considering a chunk of the pot is missing.  Would other collected ceramics retain this much of it’s value when repaired?

Here is a small Tofukuji pot that hasa very large crack on it.  I was told that this pot would have retailed for about 700 dollars un-cracked.  Not sure what the value is now but people have suggested 100 – 200 dollars because it’s still a Tofukuji pot.  If it was another less known maker, I’d have a hard time giving this pot away.  If you don’t know Heian Tofukuji, he has since passed away but was and still the most famous Japanese Bonsai pot maker.  His pottery are highly collectable and prized.  If you would like to know more about Heian Tofukuji, please visit Sam and KJ’s blog on suieski and pots.  They have a really good post about Heian Tofukuji pottery there.

2. Prevent further damage – if the pot is somewhat valuable, knowing that there is a  crack is important because you don’t want the crack to grow bigger.  Once there is a crack on a pot, any subtle impact or even putting a tree into the pot may cause further damage. Once cracks are found you have a chance to get the cracked fixed.

Difference between a regular crack and a surface crack from the kiln

Here is an example of a surface crack created during the firing process.  When you tap on this area, it passes the sound check which tells me that underneath the crack, the clay is still intact.

Here is another example of a surface crack on a Chinese Antique pot.  Again, it passes the sound check.

Let’s get to the fixing!

There are multiple cracks on this pot and here is the largest one.  The crack is about 7 in long (18cm)

It looks like someone put some kind of adhesive on the crack before but it’s starting to peel off.  I used the bamboo stick  to scrap off the old glue.  I try not to use anything that is too abrasive on the pot because I don’t want to loose the patina.

After I removed the glue, I washed the pot and lightly scrubbed the area with a non abrasive plastic brush.

The Japanese equivalent of crazy glue is what I’m going to use to fix this crack.  Be sure to buy the liquid version and not the gel version.  The liquid will wick into the crack and give you a better bond.

Here is a crack with the glue applied.

I let the glue penetrate for about 10 seconds and wiped the excess off.

Here is the crack after the glue dried and I oiled the pot.  The crack line is still there but less noticeable. Now when I tap the pot, it has a nice resonating sound.

Here is a corner of the pot that has multiple cracks

After the repair the cracks can still be seen, but less noticeable.

Caution!

This simple way of fixing cracks are not permanent.  After long term exposure to moisture, the glue will start to deteriorate and the pot can potentially continue to crack again.  Having said that, this is a quick way to temporarily hold a crack together.   A real fix done by a professional can be very costly depending on the type of pot and it involves adding pins or staples to hold everything together.  If the pot isn’t worth very much, it may not be cost effective to get it professionally fixed.  The nice thing about the professional fix though is that the repaired area will actually become stronger then the rest of the pot so a break will never occur there again.  Sometimes the professional work is so good that you can’t tell the pot had ever been repaired.  It takes advance techniques and knowledge of pottery to spot out the almost perfect repairs.

More to come

In the future, I will post more about pots themselves and some of the repairs I come across.  There are so many tricks out there to fix cracks, small imperfections and even filling chips with gold.  As always, I will post as I learn more.

Here is how the Tofukuji pot pictured earlier in the post was repaired.  The person that did this used some sort of cement and applied it only on the inside.  I’ve yet to try this but I will give it a shot and report back.  I am also in the process of learning how to piece together pots that have broken into several pieces so that post will be coming in the near future.

If you have your own stories about repairing pots, please share them with us in the comment section below.

Thanks for reading

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10 thoughts on “What a Crack Pot!

  1. Elliott Farkas says:

    Peter
    How would you clean up an old pot that has allot of that calcium and lyme build up without washing off the patina?
    At the recent GSBF convention, I won a ficus tree in the raffle that is in an old blue/gray shallow oval tokonome pot. Its almost white with that mineral build up.
    It could be a very cool and beautiful old pot if I can get that crud off.
    On another topic, Are you already booking dates for yourself for when your done with your aprenticeship? I would like to get you into the next GSBF convention in So. California when you are done.
    Elliott

    • Peter Tea says:

      Hi Elliott,

      Thanks for the comments and suggestions. I would like to try some of that glue for future pot repairs.

      As for the pot questions, that has always been a problem in California. The water in Japan is so much cleaner so there isn’t much talk about calcium buildup. I did ask Mr. Tanaka and he said that if you put the pot in a bucket of clean water, it would take at least 6 months before the build up on the pot starts to dissolve. I have heard some good results when people put their pots in water with a light solution of CLR or lime away. I’m not sure how it would affect the patina because I’ve yet to try it myself. My guess would be that the chemical will effect the white calcium first then affect the patina. Perhaps getting rid of the calcium and loosing a little bit of patina isn’t too bad of a trade off assuming that the buildup doesn’t happen again. :o) I did buy a pot that has a thick calcium build up on it recently and planning on doing some experimentation on how to effectively remove the build up without loosing the patina. I’ll post more about it and the results when get a chance.

      I haven’t started booking dates for my return yet because I’m not sure when that is. I’ve done workshops for the convention before and have always had fun doing it. I’ll always schedule things around the convention anyways because I like attending them so I’m sure we can make something happen in the future. When I know when I’m going back, I’ll post something and let people know. Take care Elliott

  2. Penny Pawl says:

    Really enjoying your updates Peter. Enjoy every second. And keep the updates coming.
    Penny

  3. Elliott Farkas says:

    Hi Peter
    As I said before, at the end of your training in Japan, all your post’s would make a great book!
    I discovered another possible way to repair pots that I plan to experiment with. I read on Boinsai basho .com under the advanced techniques articles about a new wood hardener that some of the Europeans are using called paraloid b72 (AKA acraloyd B72) It is used by museums to repair and preseve wood and paper. It comes in little plastic beads that you disolve in acetone into a liquid. Thinner for wood preservation and thicker for gluing a broken jin or something. Since minwax is now illegal in California, I found a preservation Company in New York called talas (Talasonline.com). I ordered some and it definatly works better than minwax and comes out way cheaper. I noticed that they also sell other formulations of this acylic for metal and ceramics. Museums use it to preserve and repair old pottery.
    It lasts much longet than super glue and you control the viscosity by adding more beads or acetone. Im gonna order some of the ceramic formulation and try it out. What I like about the paraloid, is that at least on rotten wood, it permeated better than the minwax and left vrtualy no sheen. What little sheen there was (way less than the minwax) I just dipped a toothbrush in some acetone and lightly rubbed the wood. That took care of any telltale sign’s.
    I will puposely drop a cheap tonga pot or something and glue it back together. Will report my fingings.
    PLEASE keep posting! Elliott

  4. Thanks for the information. I have used cyanoacrylate instant glue to repair hairline cracks. I have seen gold used to repair old pots that Jim Barrett owns.

    • Peter Tea says:

      Thanks for the tip Michael. I’m going to start experimenting with many different glues here and see what kind of results I can get. I will add cyanoacrylate to the list. Thanks and take care

  5. cherylas2009 says:

    Nice post, Peter. I have used crazy glue or gorilla glue to glue broken pots together but never thought of treating cracks in any manner. Good idea.

  6. Tung says:

    I’ve used epoxy glue to fix my pot cracked or make a bonsai display by gluing a flat stone to a stone pole. It works like a champ.

  7. Tim burke says:

    I had a Jim Gremel red pepper clay pot i thought was the cats meow until a friends child threw it to the ground and broke it in three or four pieces, after morning the loss for a couple days I couldn’t glue it back as the memory needed to fade, still not sure if I made the right choice? Great post Peter keep doing what you do….TJB

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