Saturday, 25 December 2010

Casting using concrete or wax or jesmonite


You can make all kinds of objects out of concrete. They will be heavy, but this can be an advantage when you want to construct something that is durable -- especially for outdoor use. You can cast your own paving stones, sculptures, wall hangings, feet, water feature basins, rocks and more. Here are some basics on how to cast different concrete shapes.

To make shapes out of concrete you will want to build a form. The inside of the form will define the shape you are creating. Then when you fill your form with cement and let it harden you shake loose or break open the form and have your finished object set in solid concrete.

Do your design first. Sketch it out so you know how it will look. If you are making a form for a single use, like the bowl for a small water feature, for example, you can construct it out of materials that can be broken away later. If whatever you are pouring in concrete will have layers of texture applied, you don't have to be fussy with the mold itself. You might want to simply use wood to create your form

Make a frame or form from rough materials like wood, or more exacting and detailed molds from foam, plastic, silicone, urethanes bought from industrial suppliers or craft shops. You can even make a flat textural piece you can press into the surface of wet concrete like a mold-type stamp. There are also wonderful selections of pre-cast molds available to buy on the internet and in specialty stores

You will want to clean your mold before using it and, if it is a flexible mold, lightly oil the inside to keep the cement from sticking. (You can buy a lubricant or use 5W-30 motor oil.)

Mix your cement and pour it into your mold. Portland cement creates an nice smooth concrete but is less strong than mortar. Cement mixes work well, too. For fine work you may prefer to use plaster. If you are doing something small enough to move, pour in a quarter of the mixture at a time tapping or lightly shaking the mold to release air bubbles

Let the cement set for 24 hours and either break away a solid mold or shake out a flexible mold to release your creation

Chip clean any little unwanted pieces and coat it with texture, leave as is or paint your final product. In the end you will have a cast concrete shape you can have for practical use or decor!

Some artists who cast in concrete

Jennifer Cohen - USA
Sculptor graduate from Yale 2000

Grey Line in Six Parts (i) (2008)

Each work is an amalgamation of the static and the kinetic, with the depersonalized concrete structure segueing into the vividly suggestive flourish of the shoe or the glove. In Cohen’s work there is a clear separation between the body (as represented in the concrete structures) and the objects that adorn and embellish it. These objects are grafted onto the body, injecting the abstract form with a distinctly animate aspect. Yet the sense is less of political engagement than of uncanniness; Cohen’s work is unsettling precisely because of its lack of a clearly declared agenda.

Untitled (2008)

Elizabeth White - USA
"Affiliations with conservation/educational organizations have matured my awareness of people's connections with nature. Desire for harmony with my surroundings prompted me to delve into the study of specialty paint techniques, trompe l'oeil and the practice of feng shui. My current sculptural works range from ephemeral to concrete in my use of natural and found objects, and cement. The commodity of human hair inspired the continuing series called "Renewable Resource". Fear of the irreversible pollution to the environment and our gene pool inspired the protest with the "Dirty Bomb" series."

Rachel Whiteread - UK

Untitled (Nine Tables) 1998
Concrete and polystyrene
displayed: 681 x 3750 x 5190 mm
Presented by the Tate Collectors Forum 2003

Whiteread makes casts of carefully chosen objects, most of which bear the trace of human use. She casts the ‘negative’ spaces around or beneath these objects, which then become the ‘positive’ forms of the sculptures. In Untitled (Nine Tables), the artist takes a familiar item of furniture, but presents only the residue or memory of its presence. This evokes the past of the object as well as the lives of those who once used it. Whiteread has said: ‘I always use secondhand things, because there’s a history to them.

N.B. no to be confused with 'Concrete Art' - which is a term introduced by Van Doesburg in 1930 'Manifesto of Concrete Art' published in the first and only issue of magazine Art Concret. He called for a type of abstract art that would be entirely free of any basis in observed reality and that would have no symbolic implications. He stated that there was nothing more concrete or more real than a line, a colour, or a plane (a flat area of colour). The Swiss artist Max Bill later became the flag bearer for Concrete art organising the first international exhibition in Basle in 1944. He stated that the aim of Concrete art is to create 'in a visible and tangible form things which did not previously exist ¿ to represent abstract thoughts in a sensuous and tangible form'. In practice Concrete art is very close to Constructivism and there is a museum of Constructive and Concrete art in Zurich, Switzerland.


Lost-wax casting sometimes called by the French name of cire perdue (from the Latin cera perduta) is the process by which a brass or bronze sculpture is cast from an artist's sculpture; in industrial uses, the modern process is called investment casting. An ancient practice, the process today varies from foundry to foundry, but the steps which are usually used in casting small bronze sculptures in a modern bronze foundry are generally quite standardized.

Candle making video



Artists that cast and sculpt in wax.

Eleanor Crook


Although it has been around since the 80’s Jesmonite is a relatively little known material despite the fact it remains one of the only water-based resins around today. Jesmonite is made up of two components, a liquid acrylic compound that binds a gypsum powder (not unlike that used for plaster casting). The resulting mixture acts much like plaster for 24 hours or so then hardens to acrylic-like properties. It is ideal for covering large foam sculptures by itself or together with fibre-glass matting to add extra strength. Because it is a water based compound, all the protective equipment necessary when working with G.P resin and fibre-glass is not required. Although a dust mask and goggles are essential when mixing any powder or liquid. There are several types of Jesmonite already available and new developments released in 2008 included the introduction of metal finishes for cold metal casting. Because it is a water-based resin, it is also ideal for coating polystyrene sculptures and foam core furniture designs with a durable, exterior shell, which can be sanded painted or upholstered to meet the users needs.

On its own it is very strong, it’s even weather proof, much like the properties of plastic, yet when combined with fibre-glass matting it becomes extremely strong and highly durable. It is also impact and flame resistant.

It is very popular when making large or load bearing structures particularly when used with polystyrene block sculpture as a core. This keeps the weight to a minimum whilst not compromising on structural strength. It is also suitable for making children’s toys and interactive sculptures where conventional resin/fibre glass usage would not be suitable.

How do I use Jesmonite?
Jesmonite is supplied in two parts, a liquid and a powder, these are mixed at a ratio of between 2-3 parts powder to 1 part liquid. Digital scales are not necessary to measure this material.

1.Measure out an adequate amount of powder first and add the acrylic liquid at a ratio to suit your work. Remember, the more of the acrylic liquid produces a runnier liquid. Check with your technician what viscosity suits your work best before starting.

2.Once combined the powder and liquid begin to react quickly so do not delay mixing and application. I find using an electric whisk or similar for about 1-2 minutes is enough to ensure all the lumps of powder are gone and it is a smooth texture before applying.

3.The mixture can be applied by brush as a plastic coating or in conjunction with fibre-glass. It can also be poured as a solid or a hollow slip casting.
Tip: The more powder you add the thicker the material becomes. Handy for filling the bits you’ve missed. Also adding more liquid will thin the material, making it ideal for casting highly detailed surfaces.

4.After around 15-30 minutes the surface can be worked like plaster, which makes it a great choice for fabricating complicated one-off shapes quickly and easily. Over the next 24-48 hours, the jesmonite will gradually harden into a tough plastic like material that can be cut, shaped, sanded and painted.

the silicone rubber mould before jesmonite is applied

jesmonite applied and has set to create a cast of the horse

A finished piece of jesmonite casting - a giant pink sculpture of a toy horse - with a shine that jesmonite gives.

Artists who use jesmonite

Jilly Sutton - UK

The Ponderer
Limited Edition
68cm x 61cm x 41cm
Edition of 12

Melanie Deegan - UK

Heron in Jesmonite built up on a wire armature and mounted on a wooden base. Similar pieces can be commissioned as a house or garden sculpture.
Base approx. 30cm x 50cm
Height approx. 150cm

Sculpture inspired by an image of a Borzoi or Russian Wolfhound. Created in Jesmonite built up on a wire armature and mounted on a wooden base. Similar pieces can be commissioned as a house or garden sculpture.
Base 150cm x 40cm
Height 90cm

Borland's practice negotiates territories in art, ethics, medical humanities and bio-politics. She gathers her source material as a result of research time spent in medical and forensic institutions, observing and participating in their practices. Borland does not merely expose her findings within the gallery but creates deeply poetic works that reinvest the clinical data with a human dimension, introducing aesthetics and ambiguity to an arena dominated by function and objectivity. Her observations often raise unsettling questions simply by making visible an arena usually inaccessible to the public.

Given the sensitive nature of her work, Borland has devised a personal moral framework, analogous to the Code of Medical Ethics, which serves to inform her practice and her choice of materials. Borland trained at The Glasgow School of Art and University of Ulster, Belfast, she has since collaborated with the Medical Research Council's Social and Public Health Sciences Unit, the Medical School at Glasgow University and the Penninsula Medical School in Cornwall.

Cast From Nature - Glasgow Sculpture Studios - 2010 to March 2011

The work involves creating a cast of a man who died and was dissected in the 19th century. Over the next three months Christine and her assistant will painstakingly take moulds from the cast, which she found broken and dusty, in storage at Royal College of Surgeons.

The process of creating this figure can be watched live by the public. However they aren’t allowed into the room where Christine is working. Instead, they can watch two live video feeds from a nearby gallery – one showing a wide-angle shot of the room, with it’s stainless steel tables and equipment, the other showing an overhead shot of the body as they work on it, with scalpels, razors and clay.

The idea is to recreate the aloof, removed viewpoint that would have existed in the dissection theatres of 19th century.

This was also a challenge when it came to recording Christine at work. Instead of being in the room, I had to be next door, watching the action, and describing it – whilst a recorder I left in the room recorded them as they worked.

SPIRIT COLLECTION - April to May 2000 - New York (Sean Kelly Gallery)

In "Spirit Collection," Borland has expanded her discourse to include a hot topic -- genetic science -- that also happens to hit Borland close to home (She is from Scotland and it was a Scottish biotech firm that cloned Dolly the Sheep and cells for Millie the pig). Borland has also presented her work here with more care. This installation is both varied and engaging. Works include a video of an animated 19th-century drawing of a boy with Duchenne Muscular Dystrophy, a sculpture consisting of several sets of painted porcelain female pelvises paired with baby's heads in birth positions, photography of bioluminescent jellyfish, and a microscope revealing the quickly-multiplying HeLa gene.

The centerpiece of the exhibition, however, is the eponymously titled Spirit Collection (1999). Numerous vaccum-sealed teardrop-shaped glass containers hang overhead, each filled with a combination of ethyl alcohol, preservative and water, and each containing a leaf. The leaves themselves look unreal, for Borland has bleached them white in the manner of makers of Victorian bell jar curios. But they are very real.

When the artist was working with geneticists at the University of Glasgow, she saw a tree outside the window of the Genetics department -- an undistinguished tree, in a not very prime spot over by the car park. She was told that the tree was grown from the seed of a Plane tree in Kos, Greece, under which Hippocrates, the father of medicine, first taught his students. While the locals knew little of the circumstances of the Glasgow seedling (more information was proffered after Borland's exhibition of Spirit Collection last year in Dundee, Scotland), Hippocrates' original tree is a famous, revered, ancient monstrosity, propped up on all sides -- a place of pilgrimage.

Borland harvested some leaves from the tree, and here they are. The leaves are preserved to emphasize their piece-of-the-true-cross "sanctity" as actual genetic material. Cherishing their origin, Borland defies the culture of cloning. But Borland's presentation of the leaves of a tree's "family tree" -- white, weird, spooky, afloat in the solution in a Frankenstein way -- also suggests that she fears that originals are being rendered ghostly in the age of the clone. The piece functions then as a sort of "burning bush," which fills the mind with all sorts of questions about the ambiguities of life after DNA research.

Five Set Conversation Pieces (1998) includes five female pelvises molded from obstetric models. Porcelain babies' heads are set in different positions by the pubis bone, while the upper bones are painted like old "china trade" china with blue ships, islands and trees. In those old days "bone china" meant wares actually made with ground-up human bones.

Borland implies that the birth process is a weak link in the saga of genetic material -- some positions, in the time before widespread C sections, led to still births -- yet DNA lived on in the china. Just think -- you could clone your great granddad from an old teapot. Not really, but its just the kind of startling thought that Christine Borland stirs up in this provocative exhibition.


millinerclaire said...

Thank you for writing this post! I am thinking about starting to use jesmonite, and experiment with casting it into plastazote structures (then removing the plastazote - so essentially the plastazote shape is a waste mold).

I was looking for some info on what jesmonite is, and this post was perfect. Interesting and informative. Thanks again!

Clemens said...

To make shapes out of concrete you will want to build a form. ...

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