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THIS PAGE is a copy of an article I have written for a past issue of the Metal Arts Guild's MAGazine. The readers would be jewellers and metalworkers.

By Andrew Goss

Why precious? And what has concrete got to do with jewellery and metalwork?

Concrete -- a mixture of portland cement, water and aggregates -- is about as far from preciousness as you can get. I wanted a material that challenged some ideas about jewellery. Using concrete in jewellery could be a metaphor for value, for what we consider precious.

In the time of "The Great Upheavals" in jewellery (the late 70's and early 80's) a lot of us worked in alternative materials, so I'm not claiming new territory. Back then I made difficult-to-sell jewellery using photocopied words and images laminated in plastic. Some of that work talked about value and preciousness. I guess I've been trying to get back to those ideas ever since; a Canada Council grant finally made it possible.

What ideas? To express it positively: real value is in the beauty, in the art or craft of what we make with our hands, our hearts and our minds. Negatively: real value is not in the preciousness or the cost of the material that we use. Most other crafts accept these ideas as given but a lot of jewellers and their customers support the view that value is based on rarity or cost. How many times have you been asked: "How much silver (gold) is in that piece?"

If I discard the idea of value based on rarity and cost, then I am left with a challenge: to take an unlikely and inexpensive material and make something beautiful, something desirable, out of it. Concrete. We take it for granted in our buildings and we walk on it every day. I've used it in house building, renovations, mortar and stucco and over the last few years in sculptural pieces and boxes.

I began by doing research into how portland cement is made. It is manufactured from calcium (usually limestone, sometimes chalk) and silicates with aluminates (clay, shale or sand). These materials are roasted at a high temperature then ground to a powder. When water is added it "hydrates," combines with the water to make a strong stone-like material which binds the aggregates (like sand or gravel) together. The hardening is similar to plaster, only it continues forever and is resistant to water.

On a jewellery scale I started by using straight portland cement and water, no aggregates. I ended up with a smooth uniform material, but it developed some problems such as shrinkage cracks. I called my local ready-mix supplier (Miller Cement, whom I had used for advice on a drinking fountain I did a few years ago --- "You're making what?") and they suggested adding latex to the mix. It toughens the cement on a small scale, and also helps waterproof it. I also added polypropylene fibers. They help prevent shrinkage cracks during the initial set. I added sand too, noting that the quality and colour of the sand was important to the look of the finished piece. Ledgerock, a local limestone quarry gave me some stone dust that comes off their diamond cutting wheels, and I have had good success with that as a fine aggregate.

I made simple brass molds to generate the forms, then wet sanded the pieces. I also added metal filings to the mix and tried white portland cement combining it with brown, grey or white sand. Bronze filings in the mix turned the white portland a pale blue. I learned that concrete connections to metal must be mechanical.

I took the simple forms developed in the jewellery and made larger objects, using metal and wood molds. I added steel mesh for strength (concrete is very weak in tension, strong in compression -- steel is strong in tension). During a summer course at Haliburton I learned about two other additives: air entrainers, essential for frost resistance, and plasticizers, which allow you to use less water, thereby increasing strength. Even with the large forms I continue to use fibers as an additive. I also developed a web site about this project to share the information I was learning, showing finished pieces of my own and other artists and jewellers. Through the internet I learned a lot about different additives, although sourcing them has proved to be difficult. I use drops and teaspoons of these additives and the manufacturers sell them in barrels. Other artists in Canada, the United States and Australia have emailed me with questions and suggestions.

The ideas and the technology have developed parallel to each other. I started with simple forms, concentrating on the honesty of the material, changing scale frequently, using precious and non-precious metals, diamonds and zircons. Some of this work will be shown at Prime Gallery in Toronto, April 1 to 24, in a show called "New Work: Precious Concrete."

More details are on the web site:
I welcome images of your own concrete work to add to the Guest Gallery section.

By "cement" we usually mean portland cement, a fine powder which hydrates and holds the aggregates together in concrete. "Concrete" is any mixture of cement with sand and/or crushed stone.

Cement seems benign, but it has definite hazards. It is caustic before and during set-up; it can abrade your skin, which can take a long time to heal. Wear gloves. The dust has silica (hence, silicosis, emphysema) and chromium contaminants (hence, dermatitis). Wear a mask.

You can buy bags of pure portland cement, or dry mixtures such as sand mix (cement and sand), mortar mix (cement, sand, and lime) or concrete mix (cement, sand, gravel). These are two basic but flexible recipes I developed using pure cement.

A. SMALL SCALE (jewellery, e.g. inlay):
- 2 tsp portland cement (gray or white)
- 2 tsp stone dust or very fine sand (optional)
- or 1 tsp clean metal filings (bronze, sterling etc)
- pinch polypropylene fibres (eg 'Fibermesh')
- latex (latex:water 1:3) (add slowly, only enough to make workable)
B. LARGER SCALE (casting or built up work):
- 2 L portland cement (gray or white)
- 4 L sand (sharp or brick sand, or white sand)
- crushed stone (optional, for larger pieces, ratio cement:sand:stone 1:2:3)
- about 40 ml of polypropylene fibres
- 1/2 tsp air entrainer (such as 'MicroAir,' optional)
- 2 tsp plasticizer (such as 'Pozzolith,' optional, so less water can be used)
- water (add slowly, only enough to make workable, how much depends on moisture in sand)

Mix the dry ingredients first. Try and break up the fibres into the mix. Add the liquid additives to a small amount of water first, add that liquid to the mix. Then add only enough water to make the mix usable. Mix well. The concrete will start to set in a few hours, will feel solid in 24 hours (when it can be carefully filed or shaped), and should be kept damp or covered for at least a week when it will be four times as hard as the first set.

Other additives:
-Glass fibres (alkali resistant) sound like a promising additive and can replace steel reinforcing, but I have yet to source this material. Paper pulp can be added to cement to lighten the weight.
-Concrete can also be dyed with specific pigments: ochre, black, brick reds, blues and greens. Too much dye can weaken the concrete.
-Sealants: I use an acrylic sealer (a waterproofing agent) and sometimes a paste wax, but I have been told that silane or siloxane sealants are superior and penetrate deeper.

~Andrew Goss

Last update: January 30, 1999.

This project was originally made possible with the assistance of The Canada Council