Art Concrete How-to>
2: Very Small Scale
THIS PAGE is one of several explaining techniques about how to use concrete in small-scale art projects.
Book: Concrete Handbook for Artists: Technical Notes for Small-scale Objects. More information?
Working with portland cement at a jewellery scale has led me to mixtures that use few aggregates. Even sand seems too coarse for some jewelry. The mix is portland cement (white or grey), polypropylene fibres (optional: to reduce shrinkage cracks as shown at right) and water or acrylic or latex solution (optional). I have recently had success using waste grindings from a local limestone quarry in a 1:1 or 1:2 ratio with the portland cement. Cement with no aggregates can lead to a lot of shrinkage. See the materials page for more details.
This is a reliable mix:
-- 1 tbsp stone dust (screened, limestone or marble)
-- 1 tbsp portland cement (grey or white)
-- half tsp metakaolin
-- pinch fibres
-- (optional) 1 tsp metal filings (silver, bronze)
-- acrylic or latex solution (as little as possible)
The cement is mixed well -- it should be thoroughly wetted, but not liquid -- and placed in the mold, or around a framework (see bracelet) and covered with plastic wrap for 24-48 hours, making sure the surface does not get dry. After this period it can be released from the mold and wet sanded to shape. Small air holes can be filled with a mix of the same proportions and covered for another day then wet sanded again. After a weeks curing (covered, not allowed to dry out) it can be sealed.
This concrete bracelet has a silver ring as the main structure. Silver pegs were soldered around the circle, then drilled. Stainless steel wire was threaded through the holes and wrapped around the pegs. A mixture of portland cement (2 tbsp), stone dust (2 tbsp), silver filings (1 tsp), fibermesh (pinch) and latex solution, was pushed into and through the armature. The concrete was supported on a concave surface while it set. Filing and wet sanding the concrete after two days completed the rough shape of the piece; final wet sanding and sealing with siloxane about a week later.
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Last update: 2016.