Over the past year I journeyed through the path of making cement bonsai containers. This path had many forks, turns and dead ends.
Early internet posts recommended Hyper Tufa, Papercrete and Ciment fondu. I have seen instructions on fiberglassed slabs, mixing peat moss and Portland cement, mixing up Ciment Fondu and so on. It was ok but I thought very mediocre.
I then saw Erik’s pots
Great now we are getting somewhere, he raised the bar. A very high high bar. Hmm can I jump that high? Mind you Erik is a trained artist and a very good one at that.
So with my stick man artist skills I decided to try and do what he does.
What’s first? The medium, so what do we use? Cement of course, but what KIND???
Well I went from simple to complicated formulas and back to simple.
Concrete countertops tweaked my interest. Glass Fiber Reinforced Concrete or GFRC as the industry called. Basic ingredients are:
Alkali Resistant Glass Fibers
No reinforcing required very strong and lightweight.
Premixed bags are available for around $35 a bag (22kg)
Mapei makes a similar product called Planitop X stronger and lighter for around $50 per bag (22kg) great for free forms without any extra reinforcing.
A little definition here, cement is used to make concrete and grouts.
Concrete is a mixture of cement plus adjuncts (navvy jack, sand etc.)
Grouts are a mixture of cement plus adjuncts and admixtures.
I spent a year playing with the above but still could not get the cement to finish as I wanted to.
I ended through my local hardware store getting in contact with the manufacturer of Quikkrete products. So after a lengthy conversation it was suggested that I use something simpler that is strong, light and economic for my purposes.
The quick and easy is this;
Quikkrete Portland Expanding Grout – $13 per 22kg bag
Sets in 10 minutes, can be sculpted for up to 12 hours or longer depending on temperature.
1/2″ by 1/2″ hardware cloth, the 1/4″ stuff is good for smaller items but too flexible for anything larger.
Cut and shape the wire mesh to whatever you wish, no wrong way here.
Cut out Tulle to fit I use a spay adhesive glue in place
Mix the grout well 3 minutes minimum I sometimes add a little Portland type 10 cement (not concrete mix).
Sika makes a similar product but the sand is a little coarser and contains more calcium aluminate.
Okay I am there or am I ?? No I needed to develop 3 new skill sets.
Hmm I am Stick Man Level 1 but I need to get to Level 2. Containers came out ok but my wire cloth designs needed work. So with a little patience, experimenting and practice with the wire mesh I managed to get to Stick Man Level 2 as far as wire mesh skill. An engineering course would here.
Next skill set is applying the grout mixtures, what I did learn was making different slurries from wet mixes to drier mixes for different purposes. Small batches of mixes are key you only have 10 minutes, tools to apply the mixes are important also, palette knives work great also cheap thin metal spatulas, bread knives all can found at a thrift store (Salvation Army for one).
After a couple of hours the grout can be worked but be careful it is still in the green state you can wire brush, sculpt don’t move the piece though at this state. After 12 hours you can still work it wire brush etc. After 3 days it is very hard and you will need strong tools.
This skill just needs practice. Those of you that are familiar with clay modeling will do well here.
The third skill is the painting, I made mistakes by using solid color outdoor stains. Solid colors filled in all the little cracks surface features I created and gave the container a fake look. Switching to semi-transparent stains gave the look I wanted and I have since purchased and airbrush and having a lot of fun with that.