Wednesday, September 14, 2011

Concrete Beads

Often, tools and materials determine a design. I stumbled across this silicone pad in our local hardware store -- a hot plate for pots in the kitchen. It was pale blue and very flexible, divided into open squares of about 5 mm, each hole about 2 mm deep. Silicone is a great mold-making material for concrete, so I bought it not knowing at the time what I would do with it.

5 mm squares after they are released from the silicone mold

First, I was thinking the texture would look great pressed into the surface of a larger concrete sculpture, but then I thought of beads, lots of beads. I sprayed the surface of the pad with a release agent, then mixed up a fairly fine mix of Portland cement and stone dust (1:1), with 10% metakaolin, a bit of black dye and some PVA fibers. This was spread over the surface of the mold, then packed with a small rod into the square spaces, smoothed off, and covered in plastic sheet for a few days. When I pulled the concrete out of the mold, the fibers held most of the squares together, so I used a utility knife to slice them apart. The squares were then immersed in water for about a week.

After the week was up and the concrete was probably 90% cured, I drilled each bead with a .9 mm (.035") metal drill. I drilled from both sides to try and keep the hole centered. The next step was to wet-sand all the surfaces by hand, using a 400 grit sandpaper. This gave a smooth surface to the beads and also got rid of all the surface fibers. To round off the edges (rather than hand sanding such tiny shapes) I tumbled them with steel shot for an hour. When they came out of the tumbler, this is what they looked like among the steel shot:

Tiny square concrete beads in steel shot

The plan is to use these concrete beads in some minimal jewellery designs, such as the partly completed earrings below.

Draft earring design, sterling, titanium, concrete


Scott said...

Very nice and creative Andrew. I've made a few small pieces (not as small as what you have) and added wire and metal shavings which also gave it a nice effect.

Thank you for sharing. BTW, I purchased you book 2-3 years ago and have found it very useful.

korinta said...

I always would like to go through your blog..And i always find it interesting too..

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Anonymous said...


I like this silicone mold.
Any idea wher to get them from?
thank you for your help..

Unknown said...

mixture of cement to polystyrene is important process..and one more thing look for is..cement and sand to mix well..
Complete cement plants

sarawelder said...

I love this idea partly because I have 2 of these silicone pot holders ( ac4u - available at kitchenware stores etc) which release agent did you use?

Unknown said...

I am always impressed with art made from concrete. Edmonton has a lot of them scattered throughout the city. They are quite beautiful.

Unknown said...

They say there's no stupid question so: "the squares were then immersed in water for about a week" Why?