DIY Concrete Face Garden Sculpture – Part #2 Mold Making

Why not be able to share your great designs by making a mold from them?! My huge face sculpture will now be able to be duplicated as I’m sure you have a few spots in your garden that could use a bit of ‘personality’! Each one of these will be unique even though they are cast from the same mold. One of the easiest casting projects to make your own mossy DIY Concrete Face Garden Sculpture Mold.

You will need some type of mask or one that you made yourself (like mine here) It was not as difficult as it may seem; you can interpret a face so many ways to be completely original and even more ‘artsy’! I decided; go big or go home! (over 2x human size)

DIY Concrete Face Mold Supplies:

  • Your original ‘Sculpture’
  • Large (non precious) bowl
  • 100% Silicone Caulking (I used 3 tubes)
  • Corn Starch (3 boxes)
  • Caulking gun & xacto knife
  • rubber/nitrile gloves
  • rolling pin

Step #1; Get the form ready

I have not added any release agent such as grease or spray to my original shape. (yes I like to live dangerously sometimes) However feel free if you suspect that your surface is going to be sticking.

This concrete is somewhat rough but I also did not like the idea of greasy film on either piece. IF, you would like to add some, I would NOT suggest any cooking spray. I like using a stiff mixture of beeswax and petroleum jelly (vaseline), and scrubbing it in with a stiff brush if you want a release agent.

Step #2; Make your Molding material

I have had much success with this method of mixing 100% silicone caulking with cornstarch. It will create a rather stiff but still flexible mold. Squeeze about as much as you think you will need (may mix up more to add if needed) This large mask used about 3 tubes total. DO have good ventilation for this as the fumes from the caulking (vinegar smell) is quite strong.

Work the cornstarch into the caulking gently and keeping it as one mound. Try to keep starch between your fingers and the caulking (like working with bread dough) Keep adding and working until it starts to lose it’s stickiness. It will set fairly quickly once it does so be aware.

Give the mix a good kneading to make a consistent dough (yes, I used to work at a bakery).

To make covering this large area easier I rolled the ‘dough’ with a rolling pin. A thickness of about 1/4″ – 3/8″ was my goal. Feels almost like making a pie…

Step #3; Cover your form

I then transfer the slab to the shape and work it into the details. You will feel if you are thinning it too much and edges start to poke through, manipulate the ‘dough’ to cover.

I had run out of caulking and had to go to the store (duh, not the best idea) and then added more afterward. It joined quite well. However if there is a repair or join that you need to make use some caulking directly as a ‘glue’.

Once it is set; does not ‘squish’ when poked, it has cured. Start to peel back the edges and carefully work around all directions. It was quite ‘attached’ since I used no release agent but I was able to slowly pull it up without breaking.

Step #4; Casting the concrete

Since this mold is fairly thin you will need to provide some support for it. I dumped a couple bags of sand on the ground and wetted it. I can then nestle the mold nicely into it and it will hold the shape. FYI; historically, sandcasting was used quite often, even with molten iron.

I casted quite a few ‘faces’… I used the Rapidset Cementall entirely, a mix with reinforcing fibres and a mix with some peat moss. All castings worked successfully.

I like the rustic textured concrete look so added the peat into the concrete mix. It is already a very strong concrete to this did not weaken it too much.

It now resembles hypertufa and is also lighter. Since this will not be that thick weight was not the issue.

I have also used some colour  to add some ‘age’ to the really white concrete. You can customize as you like.

To distribute the concrete, just plop an even amount around the mold. The goal is to have the edges look broken, as if it was part of an ancient old sculpture that fallen to the ground. Varying the edges will also create different looks.

Smooth it into the crevices and aim for about 1/4″ – 3/8″ thickness. I am not too concerned about bubbles as it adds to the rustic texture.

I have not used a mold release (again) so gently work to peel it out of the mold. When I used to use the spray it left residue that I did not like at all. It may take a bit more manipulating however it will be clean!

There! I like the shapes, the broken edges, and the old-looking texture! However… I want moss on them!

I’m not a ‘pink flamingo gal’. Garden art should look like it ‘belongs’ to the setting. It should feel natural, related to the media and colours… Like a pondering ‘rock’.

Evoking some simple thoughts…

‘Hidden like archeological find. From what century did it belong?!

Yes, moss! But this post already long enough, so it will be posted soon separately. Go… make your own DIY Concrete Face Garden Sculpture!

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      1. I just love your mold idea I would love to know the measures of ingredients, the quick set how much did it take to do the mask. for example. tks again.

        1. Well yes, everyone wants exact measurements. I work like an artist and less than a scientist. The silicone/cornstarch is worked until it doesn’t stick anymore. I bet humidity would play a role as well as how much it is compacted. It is messy and in this case I had to go out and buy another tube. This mix can be any range of ratios but if you want to be able to roll it without sticking it needs to be a pretty high cornstarch ratio. In that case it also starts to set really quickly, hence no time for measuring etc. If you want more working time then a more sticky higher ratio mix can work but your hands would be covered so it needs to spackled on with a tool and perhaps flattened just before it starts to cure. If you want to get experience, mix a tiny bit to see how it goes before investing time and money. Good luck, it can be sticky…

  1. Have you tried to form a complete mask and break it? Just curious if it has a different, more realistic edge vs one where the concrete just stops.

    I’ve got my silicone, cornstarch sitting on the concrete now. We’ll see how it turns out. I’m concerned that I had too much cornstarch, and not enough silicone…. Fingers crossed!

    1. No I have not but I find that sometimes I use some pliers to ‘nibble-break the edges as in the monster eggs I’ve even mixed in some peat in one to get a more rustic finish, and it worked as well. I use the rapidset cementall as it can still be strong enough at a very think thickness. Good luck

    1. No! That is not a corn starch, and has water in it. Cornstarch is very dry and powdery and somehow creates that ‘putty-like’ consistency.

  2. I am so inspired! Your artwork is amazing and I love the easy to follow instructions with the comments. It’s good to know it’s OK to make mistakes and experiment. Speaking of experimenting, I failed to note you made the mold in part 1. So….. This past week I have been crafting my base from a large box, newspaper, and LOTS of masking tape. At first, she looked like the Joker with a creepy smirk, so I gave her bigger lips. Then I thought she looked like an angry Roman soldier, softened her mouth and eyes. She was still too manly. I rounded out her square chin. She is kind of pretty. I wish I had her lips.
    I plan to cover her in paper mache clay and let it harden before I do the silicone mold. This is so fun! Thank you for sharing your talents and experiences! This is so entertaining.

    1. Sounds like you are having fun! That’s the important thing. Just make sure the mold material (silicone/corn starch does not stick to the papermaché, use a mold release) Best of luck!

  3. Would it be possible to use the Quickcrete Rapid set cement used for fence posts? It is 1/5 the cost of the cement-all. Or does the Cement-all have special characteristics making it better. (I do use the Cement-all for other projects)

  4. VERY Cool! I want to learn how to make these for my own garden. I’ve made dish flowers and totems which has only whet my appetite to do more things with glass and also move into concrete garden art. I LOVE the human form in the garden.

  5. Your border pavers seem “thin”. Is that because you have set them into the soil and at an angle? What size are your pavers? Thanks

    1. The pavers are about 4″ wide and set flat. They are an older style from a couple decades ago. They are set in ground so that trimming could be lessened. Happy Gardening!