Now that you have made your mold as shown here from Part 1, you are now ready to Cast your own Concrete Critter. Don’t worry, this is the easy part…
You have made a mold with some seams that open for removal. Congrats!
The Concrete Mix:
Again, as in my other concrete projects (here) I have used my favourite premix; Quikrete. Cheap and strong stuff.
Update: If you want to work faster; I have found a mix that is unmoldable in 1 hour! RapidSet CementAll. It has worked quite well with my other ‘Bunny’ casting project.
Add some Quikcrete mix to your bucket and slowly add water a little at a time making sure to stir to the bottom. (Don’t breathe any dust, or wear a good dust mask.)
To give it extra strength I have added some fibres. You can get them at any building supply place as well. If you are resourceful you could probably make some by cutting up yarn or string into pieces. They disperse themselves and help keep the concrete from cracking.
Your mold will need to sit level. I have filled a container with sand to cradle the head and keep it stable. Prop yours up with whatever you have, rags will also work well.
The Pour:
You have 2 options for pouring. If you use only the Quikrete mix you will probably have a more rustic pour with some bubbles on the surface. If you take extra care to vibrate it and poke with a skewer, there may be quite minimal bubbles.
Your other option is to coat the inside surface with a slurry mix of just portland cement. Portland cement is the active part of the cement mixes that binds the sand/stone/whatever into the solid form. Mix a small amount to a somewhat runny mix, like melted ice cream, and pour into the mold. Turn the mold round and round til it just coats the inside surface. Jiggle and tap, and it will flow. This will give it a pretty solid coating on the outside that is less likely to have any bubbles.
Once it is coated (or if you chose not as I have since I like the rustic look) you can fill the mold with your Quikrete mix. It is really crucial that you get it in every nook and cranny. I use skewer sticks to poke everywhere, and jiggle and vibrate. You don’t want a missing beak or eye! Tap the sides and turn the mold to get the mix to fill the tail.
If the weight of the concrete pushes the mold add strong elastics to keep it closed. Level off the opening as this will be the flat base that it sits on. It is now ready to set. Don’t be over anxious to take it out early or you will break off the tail. Ask me how I know?! A good 24 hours…
The finishing:
I have a really really great “Tip” that I discovered. After pouring my bowls I would sand them as well. I was frustrated with how flimsy the sandpaper I bought was. (ok, it was cheap stuff) and I saw a disk of extra concrete that I had just poured on a stone, like a coaster. I asked myself, what is sandpaper? It’s sand, just like what is in concrete. So I used this disc like a sanding block and it worked nicely to smooth out edges and seams. It is solid ‘sandpaper’.
Here are my home-made sanding discs. Pretty ingenious eh?!
Since the mold has openings, the seam lines may show as pointed out here. Take the disc or your regular sandpaper (or even a file) and smooth them off. It is concrete, not plastic, so it is quite acceptable to look rustic in my opinion.
In this world of digital reality I like some REAL TACTILE texture! Old concrete sculptures have a great ‘patina’ of texture so I really don’t mind having some here.
Here is the little fellow. Rough, yes, but it provides a nice accent to the stones and foliage. If it didn’t come out quite as you expected, you can cast again. That bag of mix will make a LOT of little critters! Make gifts or even indoor accents. I can imagine many uses and shapes. If you are really creative, make your own sculpture with Fimo/Sculpey and then use it to make a mold. Now you are completely original; casting your own sculpture
Tada! It is a ‘Small project’ yes, but still quite unique and still gratifying. Well done!
‘Want more concrete projects? I am a bit obsessed…
This Post Has 18 Comments
Great idea. I will try this. Been working in concrete over 10 years.
me gusto mucho toda la explicacion , con gracia en la redaccion , muy agradable, muchas gracias
Thank you for sharing this clever project. I can’t wait to make my own! I will also make some sanding stones. That was very ingenious as you said! I am going to use them on other projects as well. Great project, thank you!
Glad to help. I can’t wait til it gets warm again to be able to cast, as ideas keep popping into my head….
Thank You Barb
Thank you,love the way you explain the whole process.I look forward to trying this.
You are welcome! I have a few new ideas awaiting the weather to change. I love making in concrete. Check back often…
I have made several of these and I am having great success. (And fun) I just reread your blog and noticed you didn’t spray the inside of your mold with any kind of release like cooking spray. I thought it was necessary. I was going to do the Portland cement slurry to get the smoother finish but with the cooking spray it wouldn’t stick to the side. So am wondering if I should forget the spray.
I love playing with cement. the possibilities are endless. I can’t wait to see what you will be doing this summer.
How coincidental as I’m sitting here trying to figure out how I can do some casting today (as it’s snowing outside). I’m so happy that you’ve made some with great success! No, I didn’t use the release. A lot of the time if the mold is smooth plastic I don’t need it either. When I casted my ‘stamps’ I didn’t use a release either. That silicone/starch mix doesn’t seem to stick too much so the concrete doesn’t stick easily. I am able to scrub my molds and stamps quite well to clean them too.
Yes, do check back or subscribe as I think concrete my be my favourite project media… Let me know how it goes, ‘would love to see the results.
I was working on some new casting and I have tried some new mold release. I don’t like the Pam spray since it’s messy and made up chemicals probably. I made a thick paste of beeswax and petroleum jelly (vaseline) to keep my boots waterproof. It is thick and greasy but it can be applied thin with a stiff brush. The key is to be sparse, kinda a bit greasy, like our noses(LOL) just enough to prevent sticking… Worked well on my small castings. I thought I’d share
Hi Barb. I love your ideas! can you tell me how you store the silicone moulds and how long they last for?
I have kept them in my shed and in the house. They have not changed in any way that I can tell and it’s been over one year! They seem just the same, not any more stiff or brittle. I guess its like what they advertise for silicone; stays flexible for long time… I have used some dozens of time and don’t see any deterioration. Good luck
Barb, I love your postings on pinterest. You are very generous to share your knowledge. I am a beginner to sand casting leaves in cement and want to explore further possibilities. I was wondering how to affix a cement bird made from the mold to the rim of a large cement leaf ?
Thanks! I bet the bird is not that large and there is a bit of ‘play’ in how it sits. So I would think you need a fairly thick type of adhesive. I like to use 2 part epoxies (especially the 5 minute kind) or the PL construction cement. I once glued some hooks on a brick wall with epoxy, and they are still there 26 years later… Just make sure the pieces are bone dry
Happy concreting…
Wow! Thanks so much for this! Do you think I could do the entire thing with Portland cement for a smooth look? The item that I’m wanting to make a mold of is smooth and I think would look best that way. Thanks!
Since that post I have also been using the RapidsSet Cementall and it is a very smooth setting concrete, smoother than the Quikrete I used then. It is also crazy strong. Check out the bunnies. Hope that helps. Portland cement would need some type of ‘aggregate’ like sand etc…
Do you know about how many time you could reuse the mold? And do you think it would work in a larger form? (as in a long stepping stone about 30″x9″). Thanks!
I have used some of my molds over a dozen times. I see no deterioration. I made a large one for the faces and cast 7 so far. It is quite large so I use a bed of wet sand to stabilize if the mold is thin. Hope that helps, ‘would love to see end result!