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‘Paper’ Training Pots for Bonsai

The new Bonsai Book for 2019 by Harry Harrington

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This is a story of how I discovered out how to make cheap training-pots for bonsai.

With my trees asleep for the winter and with time on my hands, I thought of doing some pottery to make containers for my bonsai. Then I found this method of pot making on HBF (the Croatian bonsai forum), and having contacted a good friend of mine, Mario, I learnt the basics of the procedure that is now described in this article.

A selection of very cheap training pots that I have made using the method described in this article

The method for making the ‘mix’ to make the actual pots is very simple;

1) Gather some old newspapers, avoiding ”glossy” papers from magazines.
2) TearВ the paper in strips and soak them in water for a few days.
3) After they are all well soaked, take some paper and mix it into a fine mixture (as though making papier mache).
4) Using the same amount volume of cement as the fine mixture of wet paper, add some fine polypropylene* fibres (just a finger pinch per 2 liters of cement; this makes the final structure stronger), and mix the fibres and cement together.
5) Then mix the cement and wet paper mix together until you get the nice and even mixture (*tip- first mix one half of the cement, and then the other).

6) Add some water if needed/too dry, but the mix mustn’t be too wet, because it will make problems later on. The moisture i find appropriate is when you grab some finished mix in your hand and squeeze it hard, so that water only starts to show between your fingers.

* polypropylene fibres are usually used for strengthening concrete, protecting it against cracking; it has many other uses and is relatively easily available from builders merchants or online

From left to right: the newspaper cut into strips, soaking in water, and mixing with the cement mix

Preparing the Moulds

After the mix has been made, it is necessary to prepare some moulds for the mix to be poured into.

You can use almost anything for the moulds as long as it is water tight. It can be an old kitchen salad pot, all kind of buckets, ice cream packing or an old lamp, whatever you have handy that is a good size and shape for a bonsai container. You can make more refined moulds by shaping polystyrene or even by using plaster moulds taken from your favourite bonsai pot.

You can make the pot’s legs (if the original mold doesn’t have them) by simply making the pot’s bottom with the piece of polystyrene in which you cut out the spaces for legs with a scalpel and glue it to the bottom of the mold.

When you have the mould ready, coat the inside with a thin layer of oil (for instance cooking oil). This will stop the pot mixture sticking to the sides of the mould itself.

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©Harry Harrington 2019. All articles and images by Harry Harrington unless otherwise indicated. Use of Text or Images contained within this website is strictly prohibited without the express permission of Harry Harrington.

Large Website located in the UK, Bonsai4me offers Bonsai Art, Species guides for Bonsai trees, Bonsai galleries and Bonsai Techniques.

New product for making your own bonsai pots

Before I begin, I must say two things: first, because it is the law when writing about things like this on a blog, I do not/did not receive any compensation from the manufacturer of this product. Second, I would really and truly (and gladly) accept compensation, should the very nice people of the Sakrete© companies offer it; baby needs a new pair of shoes, you know. Ok, with that business out of the way, here is the product: ShapeCrete©, made by the Sakrete© company in partnership with a gentleman named Cheng (no, not the bonsai Cheng). Take a look at the website ShapeCrete.com

It says on the container that it plays like clay but works like concrete (it still comes in powder form though). Reason being is that to have the properties (strength, rigidity, hardness) of concrete, there is a chemical reaction that takes place between the cement and plain old water that causes it to cure as a solid.

So, we begin with a powder.

Notice the little hairy fibers, those add strength. Add water in a powder to water ratio of roughly 4:1 (less water for sculpting, but more for casting).

You’ll see some gloves today. Concrete is terribly rough on ones hands.
It seems to desiccate the skin and is terribly abrasive. And makes the hands rough and uncomfortable to the ladies. One definitely doesn’t want that now, does one?

For the he first pot, I’ll be using a colander as a mold.

Get it in there tight.

The all important drain hole.
And holes for tie-down wires; a chopstick works well for that.

I used a colander so that I’ll get an interesting texture on the outside.

Not sure how it will work but…hey, this is the first pot.

The next step is to cover the pot with plastic. This will trap the moisture in and allow the concrete to cure more completely.

It takes only 24 hours to cure enough for handling and removal from the mold. But that’s tomorrow, I have some more ingredients to play with.

I got red and black today. At the box store they also had tan, which I regret not getting. Another day.

I’m not sure how much to mix so I’ll start with a little first.

Then the concrete.
Hmmmmnnnn. Not much difference. Maybe more red.

Aha! It gets darker with water! Doh!

This time I’m using a plastic training pot as the mold.

Yes, I’m making a mess.

I had some leftover concrete so I made a freeform pot.

It’s kinda crooked. It’s sitting on a board to make feet. Or things that kinda look like feet.

I wrap them all up in plastic and then cover with a tub.

Now I have a mess to clean up.

TWENTY FOUR HOURS LATER…..

And the Plastic Pot Series©

Let’s look at the freeform pot first. Ummm, yeah. Someone will like it. Maybe.

Next is the Plastic Pot Series© I had to break off these…squirts.

And….nice! I like the smooth texture and the air pockets.

And that edge! I like it!

Now the colander.

Lesson one: concrete squirts out of holes. Like when you vomit and cover your mouth, it squeezes out between your fingers. And when it cures, it’s very difficult to remove from your mold. Very much like vomit.

Poor colander, many a pasta dish thou hast played part in. Never again shall thou drain the wet from the noodle.

Let’s see how it looks.

Not too bad. I could have made the walls thinner though. Next time.
The next step (which is not part of the official instructions by the way) is to submerge the pots in water for at least thirty days. This will ensure full cure and strength, but it will also (very importantly for plants!) leach away the excess lime that is in concrete. Lime will affect the soil ph by making it more alkaline.

I can hear the peanut gallery saying “A more alkaline soil is best for flowering plants!”

It is, but we tend to adjust it a little more scientifically by testing the ph and adding the proper amount of dolomite to the soil.

Anywho, more pots?!

These are the molds this time. A round bulb pot, and two different ramen noodle containers. I use them normally as training pots (talk about up-cycling).

This time I’m building the pots on the outside as well as the inside.

Oh, and another technique too. See the one in the back that looks like fudge wrapped in wax paper?

Put down a piece of plastic or some other waterproof fabric of your choice.

Plop down some concrete and roll it out. Maybe about 1/4″ thick.

Pick up the plastic and put it into a bowl. Here’s what you get.

It’s like chocolate! Like sexual chocolate. SEXUAL CHOCOLATE! If you don’t know what that is, go Here. You won’t regret it.

I had one failure with this batch.

I played with it too much before it was hard enough. There’s a joke there. This was the one I put over the top of the round pot.

This one came out cool though.

The final step, after they are fully cured, is some cutting to make space for tie down wires.

Before I begin, I must say two things: first, because it is the law when writing about things like this on a blog, I do not/did not receive any compensation from the manufacturer of this product. Second, I would really and truly (and gladly) accept compensation,  should the very nice people of the Sakrete© companies…