Cement rock planting?

Awsome color and texture. The smoothness is not an issue. Looks just like a chunk of Chinese limestone I bought for planting.
Rinse the chunk in a bucket & rinse… plant moss and check if it survives.
Try MIXING the oxides into the dry cement. A little more red and/ or yellow. Record the amounts. Adjust next time.
I’ll take 2…

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Hey @Jimothy, this work looks awesome. Like @moon and others mentioned, letting it soak for a bit and changing the water as the salts that dissolve off the cement and are responsible for the alkaline pH don’t get into equilibrium in the water is the usual way to go. Just let it soak and keep changing the water every few days, then seal it. My only question is regarding structural integrity, how sturdy do you think this is? Also out of curiosity how heavy? Beautiful work. One final suggestion for future pieces: instead of putting wire that eventually will get cut down to nothing, cement/attach chain links through which you can pass new wire each time you reuse this rock.

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So an adjustable chain link? To make a hole for access and drainage? image
The ones I use on my sail boat tend to rust. :thinking:
Or are you talking about a different item?

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I guess that would work but doesn’t need to be that fancy. A simple loop made of a material that resists corrosion, partially embedded into the cement would do.

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Good call, I see what you mean, if you had loops you could just thread fresh wire straight through…didn’t even think of that. Next time…

As far as the stability, i think if i’d just used the cement to bind the pieces together it might have been a bit fragile, but i think the wire binding the pieces (then sandwiched with cement) should mean its fairly secure. I don’t think it’d do too well if you dropped it from table height, but neither would most pots i suppose.

I also didnt anticipate the staining prior to the build, and would probably have benefitted from some of the oxide mixed it. Thanks Kurt, its something I will be aware of upfront (with regards to different colours too) next time.

I’m going to try an acid wash on a spare piece and see if i like the texture, and if it helps with staining…

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Oh and its probably about 6 - 8 kg I reckon.

how well did the polystyrene separate from the cement? each time I revisit this post I think…I want to make that…ha!

Jimothy…
I’ve never used “ciment fondu” …its a aluminum based cement. Would eliminate the alkaline problem… it doesn’t release lime during hydration. I think it is harder and chemical resistant too. Would take the oxides ok.:thinking:
I just gotta try this…

The polystyrene is still inside the cement! It was coated with 3 layers of cement, which is about 5 mm thick (~ 1/8 - 1/4 of an inch).

Hmm different materials may be a good call, it might be good to have a cement with fibre in it, for a bit more flexible strength (ridigity seems fine, but I imagine it wouldnt like being flexed).

Try some things out, I’d be really interested to hear. It’s good fun too.

Im in a rush to get to work but I had to take a second to tell you how great I think this looks. It’s so nice to see people being innovative and trying new sh#t at home. Awesome job man. I’ve got some suggestions that I’ll drop later, I just had to quickly say ‘great job!’

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OK, so finally the trees and moss have been planted onto this cement rock and the result is illustrated below:



A little update for those who may have been interested.
i quite like it, and was really good fun to make.
I planted the trees before Mirai put up the stream about rock plantings too, so there were a few tricks that i will include next time, which could have made the planting easier and look a bit better too. But thats fine. next time.

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Another idea for ’ naturalizing’ - a moss slurry
To make the slurry, mix 1-2 parts moss, 2 parts water, and one part buttermilk in a blender. Can make thinner -it you want more patchy- paint on roughly. Keep misted with water until the moss has established itself.

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Yeah, I heard about this technique, but havent gotten round to trying it yet. Have you had any joy with it?

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Yeah - used it on some planters back when I lived in Minneapolis. Don’t need it here in the PNW - hard to keep moss OFF stuff :slightly_smiling_face:

Also - That piece is fantastic. Well done!

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cheers, I will definetely be trying this out. I think the seeding of the muck that Ryan went through in the stream looked worthwhile too. Next time…

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Well done! I love to see other people’s methods for rock planting as I’m digging into it as well. Thanks for sharing your process.

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Cheers. Let us know how you’re getting on. This is something im new too, and would love to know any techniques (preferably cheap ones :smile:) to play with

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Jimothy, I love your work! Beautiful rock shapes.

I have been toying with and researching using cement in creating rocks, slabs, and pots for some time now, and have had the opportunity to learn a couple tips I thought I’d share.

For an alternative to polystyrene, you can use the type of spray foam created for insulation. It comes in an aerosol can, and you can build a basic shape as you spray it, i.e. spraying it over a basket-ball (cling-wrapped.) When it hardens, it can be carved with an X-acto knife, etc.

In regard to the question of pH, my research, while not scientific, was based on field experience gleaned by bonsai practitioners. What I have learned is that the higher Ph leaches naturally, as you have all found, in water. One person, who had made a small item, simply submerged it in her toilet tank for a month!

On the other hand, I was at a afternoon workshop with David DeGroot, and he was helping a student with a root over rock project. He suggested using concrete to stabilize the rock, and after a run to the hardware store for some hydraulic cement, which is extremely fast setting, they did just that. By the end of the day, they had finished planting the tree. When asked about the Ph of the concrete affecting the tree, he wasn’t concerned - he had done used it himself many times. I do not remember if the roots were planted in direct contact with the concrete that day, although I do know that they would grow to reach that area before long. For anyone who doesn’t know, he was the original curator of the Pacific Bonsai Museum, so you can decide how much weight to give to his experience.

The one thing that has held me back from creating anything significant in cement is a concern about how it would hold up through PNW winters! I don’t want to create something ambitious only to have it crack from the cold. In addition, I never found any mention of a possible chemical residue left behind by a sealer.

In any case, I’ve added to my store of applicable knowledge just by viewing your beautiful work, and after viewing Pal Tiya’s web site, and learning that it has been weather tested, I’ve placed an order for some. I think that with that assurance, I will be able to be able to proceed with the project I’ve been wanting to attempt. Hopefully, I’ll be able to share it on the boards soon!

Hi @Jimothy, nice work with the polystyrene carving!

Did you try the acid wash? I have explored this technique you’re using (cement covered polystyrene) in the past, albiet for vivarium/terrarium background building. Same as you, I navigated towards faster or more effective neutralisation of the pH by using mild acid (white vinigar was suggested). However, I found the neutralisation would ultimately compromise the structure of the cement and the bond to the polystyrene and it flaked off eventually.

I’d love to hear how this technique does in the long run, so please keep us posted. :pray:t2:

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