Having succeeded in creating items with thinner walls, I started looking for ways to end up with smooth edges, without sanding. Before I move on, I need to say that the inspiration for my solution came from watching a very cool video about a company called Obleeek Objects. Alas, I can not find their website or I would reach out to them and thank them. Check out the beautiful work he does in this fun video.
What I learned from watching this video was that he pours upside-down. As an experiment, I decided to take one of my Tupperware containers and modify it so I could make a tea light. Here is the finished product. The top, while bubbly (more on that later) is smooth and required no sanding. The bottom required a light sanding but no one sees the bottom of pots, or tea lights, so that really does not matter.
Here is how I did it. I used an IKEA container, some plastic tea light candle shells and some nuts, washers and bolts.
I drilled holes in the top of the container and also through the plastic shells then bolted that all together like this.
Next I cut a hole in the bottom of the container and then snapped the lid back on like this.
I applied a release agent (mineral oil) to all the surfaces and then poured the concrete into the mold. When it was cured, I removed it all from the mold, gave the bottom a light sanding and placed some candles in the holes. Here is another image of the finished product.
Not bad for an experiment! The groove around the top is formed by the connecting point of the lid and the bottom of the mold. While it’s interesting, I wanted to try again and end up with a smooth side wall. How to do it?
I decided to try a silicone cookie sheet. Yep … you read that right. I used the same bits and pieces and the bottom part of the IKEA container and a piece of plywood. I drilled holes in the plywood and into the silicone cookie sheet.
I then threaded the plastic shells through the cookie sheet and plywood. Then I used the wing nuts to tighten them down to the cookie sheet … like this. This makes for a very tight fit that the concrete can not penetrate.
The bottom of the container was then centered over the 3 plastic shells and clamped down using a clamp I created out of some scraps of oak, a few bolts and more wing-nuts. Here is what that looks like.
The concrete is then poured into the mold and allowed to set.
Here is the final product. Smooth walls and top … but still bubbles, which it turns out, folks like anyway! LOL
Here is a side-by-side of the first and second attempts.
Having completed this test, I decided to try using this idea to create the same concrete pot I showed you in the previous post. I used the same IKEA containers that I used to create that pot. This time, the smaller one was bolted through the silicon and plywood and the larger one placed on top and clamped down (basically, the same as the tea lights shown above).
Here is the result:
Lovely, if I may say so myself! Note the smooth edges, walls and lack of bubbles.
Getting rid of the bubbles was simple enough. I mixed the concrete, and then before I poured it I tapped the bucket on the floor about 20 times, then tapped the sides of the bucket. I then let it sit for about 3 minutes. You can see the air releasing from the surface when you do this. After I poured it, I tapped away on the sides of the mold and also used a rubber mallet to tap on the plywood all around the mold. Lots of air bubbles were released. A simpler way would be to buy a concrete vibrator.
What I learned and what I want to learn
- Silicone sheets are a great solution and lend themselves to all types of molds.
- Spend a bit more time on the mix and tapping to get rid of air bubbles.
- Tupperware and IKEA containers are very, very versatile.
For example, meet Ying and Yang! Solid domes. Paperweights? A bubbler for an indoor water feature (if they had a hole through the center)? They are quite zen, actually. Folks love to touch them! I’m NOT making that up either …
What’s next?
In the next post, I will show you the next version of my mold, which produces some beautiful rectangular concrete pots. See you then!
Read more in this series:
Part 2 – Concrete Creations: A Thinner Mix
Part 4 – Concrete Creations: A Configurable Mold!
Photo Credits
All photos by Gil Namur – All Rights Reserved
Me encantaaaaaa ! He aprendido en 10 minutos tantas cosas… Que ya es de noche en Venezuela y tengo ganas de pararme a trabajar con concreto! Gracias!
I had to translate this Leodalia …
De nada!
Im in the Philippones so Im also using basic stuff like regular cement and cooking oil.. im getting happy with a grinder too…but i would like to add a little ‘finish’ to the roughness…Im using a 1:1 mix.. its vety brittle, i dont know how long the pots will last…
Hi Disa,
Thanks for your comments. I hope your creations will last! Have you tried using Countertop Mix Concrete? Quikrete makes some but I am sure there are other brands as well.
Also – check out https://artsyprettyplants.com/. Ellen has some GREAT info and also has an e-book called The Ultimate Guide To Concrete Mixes & Sealers.
You should see if you can get that from her.
Cheers,
Gil
Thanks so much ! Im day 3 of the discovery process…Im in Manika so we have concrete..the real deal …ive been tryin 1:1 and ill experime t with 2:1 etc…and replacing the sand with other stuff.. i like the holes myself but your last pieces were really beautiful. Ive been attacking my rough pieces woth a grinder and drilling holes after… a bit rough and ready…next step in to posh them up a bit so thanks for your post.
Gil, great post I’m glad I found it. I spent 30 years in the cement industry and non shrink construction grout is a great way to go. I did many demos over the years. Now that I have been retired for some time I’m going to make several Bonsai pots for my wife and I to plant. The great thing about using the expansive cement that is used in construction grouts is that most of them can be used in fluid consistency. They are high strength, generally 8,000 psi or more in 28 days. If you mix plaster sand and cement like you see on many you tube videos the mixture if made to fluid consistency to pour will have no strength and will crack like hell. Pay a little more and pour away. Thanks for the tips.
Hi Jim,
Thanks for taking the time to leave a comment!
Good luck with your pots and thanks for the grout idea!
Cheers,
Gil
Cheaper than a concrete vibrator is a Sawzall with the blade removed. The reciprocating action against the outside of your mold for 30 seconds or less should get rid of most if not all of your bubbles.
Thanks EJ,
Great idea!!! Appreciate you taking the time to share it 🙂
Cheers,
Gil
I am brand new to this and so happy I found your post. Quick question – do you use a release agent, like mineral oil, on the Ikea bowls and tea lights? Thank you!
Hi Lauren,
I use Smooth-ON Universal Mold Release: https://www.smooth-on.com/products/universal-mold-release/
It’s a great product and easy to use. I have also used mineral oil which works very well. Pam also works but I find it leaves a food odor on the finished product. It does wear off over time though.
Cheers,
Gil
omg lol im using cooking oil! I love websites from the other world xxx
I cannot tell you how happy I am to have found your blog! This is so incredibly helpful! Thank you for explaining everything so thoroughly!!!! Really, I can’t say thank you enough!
Hi Connie 🙂
You are most welcome! Thanks for taking the time to say so!
Cheers,
Gil
Hey! Love your post and great video to share! I was wondering whether you know what the white liquid he used in the video? I look forward to more of your concrete adventures!
Hi Marina,
Probably some kind of polymer modified concrete but he is off line so it’s hard to know!
Read part 2: http://lifeasahuman.com/2014/arts-culture/creativity/concrete-creations-a-thinner-mix/
Might help!
Glad you like the posts 🙂
Cheers,
Gil
for small projects i use a hand sander up against the mold, the vibrations releases the air bubbles 🙂 i truly enjoyed reading your articles.
Hey Clarice,
Great idea. I have done the same thing.
THANK YOU for taking the time to comment! I really appreciate that!
Cheers,
Gil
Thanks a lot for these handy tips!! I just made a couple of basic cement pots over the weekend and they came up a little bubbly on top, and powdery all around. Trying to research best curing methods now 😉 Might just try the upside-down technique next time for a smoother top finish!!
Hi Chia,
I am so glad they helped! You will find the upside-down method will give a very smooth finish!
Were you able to rinse off the powder?
And what kind of concrete did you use?
Cheers,
Gil
I used 100% cement! I’m from Malaysia and haven’t been able to find pre-mixed concrete at shops yet (I did find some online by Lafarge but marketed for floor, brickwork and tiling, for contractors; not a big market for DIY here). I really like that super smooth white concrete you used! Will try to mix up my own concrete one of these days, especially once I start making larger objects that may require more strength.
I did manage to rinse off the cement powder. I guess water evaporated too quickly in the outer layers and the cement didn’t cure well. I made a second pot with more water mixed into the cement and it settled down really nicely, no bubbles, almost a shiny finish in some areas which I really like and will try to replicate over the whole object next time!
Totally loving these projects 😀 Fast and easy, doesn’t need a lot of tools/machines/space. Hope you keep on making!
Chia … you just made my day!
THANK YOU for your reply. I am going to call my friends at the place that makes the polymer modified concrete I mentioned and ask them to comment to see if they can help / suggest ideas for you.
Might take a few days / weeks for a reply so stay tuned! I will do what I can.
AND – yes – keep making – wait till you see my next projects 😉
Cheers,
Gil