9 January 2017
Stage 1 – Technical research
I am entering the moulding and casting assignment with no experience whatsoever, so I have allocated extra time to research the techniques and methods. In this blog entry, I am jotting down a summary of my findings with links to appropriate books, websites and tutorials, so that I may return to the information at a later date, should I need to.
I have had very limited experience (as a child) of making plaster of paris figures using rubber moulds. A lot of care had to be taken when pouring, to ensure that there were no air bubbles. The plaster also tends to shrink as it dries.
I learned that there are different grades of plaster, some being finer ground than others (Brooks, 2005:117). Plaster may be poured into a mould, or applied in laminated layers by dipping strips of scrim or other loose weave material into the plaster. It may also be used to make a mould from which castings can be taken.
ModRoc is a proprietary product which consists of ready to use plaster impregnated bandage and the Craftmill website gives instruction and tips for usage (Craftmill, n.d.).
Plaster castings may be made using a mould of plaster, clay press or silicon (Brooks, 2005:31). Plaster castings may be left unfinished. Alternatively, a variety of different protections and decorative surface treatments, such as wax, iron powder, paint and wood stains may be applied (Brooks, 2005:127).
Clay, Paper clay, Air-drying clay, Polymer clay, Papier-mâché and Carton Pierre:
I was initially confused by the terms for different types of clay and their methods of curing. However, I found the George Weil and Sons Ltd website very informative with an excellent range of products (Georgeweil.com, n.d.)
I have used air drying clay before. It is a readily available, cheap and easy to use material. Similar to plasticine in consistency and handling, it dries hard after a few hours exposure to air. It could be used for making moulds from a textured surface, or pressing into with objects to make surface impression. I have painted it successfully with acrylic paint. It is not foodsafe or waterproof (Hobbycraft, n.d.)
Made from pieces of paper soaked in water and bound with adhesive, papier-mâché is cheap and readily available (especially since waste paper is often used). It is possible to use layers of paper strips, or to mould using paper pulp or shredded waste paper. It is best used in hollow or shell applications (there is a risk that the centre of a large solid sculpture might remain wet).
Initial investigation into paper clay suggested that a kiln was need to fire it, unless a particular brand was purchased (for example, P’clay), and the sculpture was small and hand-held (Paperclayart, n.d.). However, I was able to find further clarification and an explanation of the difference between papier-mâché and air drying clay on the papier-mâché resource website (Hall, 2011). Hall also gives a recipe for Carton Pierre (a very fine form of papier-mâché used for moulding where plaster would be too heavy). Her version is made of pulped toilet paper combined with various readily available binding and preserving materials.
It appears that paperclay was originally made from clay slips with the addition of paper, and requiring kiln firing. These days there are some paper clays which contain no clay (nor necessarily paper!) and are air-drying (Hall, 2011). An example is “Creative Paperclay”. The product webpage says that it resembles softwood when dry and can be carved or sculptured. A different product “Delight” by the same manufacturer (also air-drying) is lighter weight and can be coloured by kneading with water-based paint (Paperclay.com, nd).
Polymer clay comes in a variety of forms. Some (such as Scupley brand), requires oven baking to harden it. Polymer clay is available in different colours, and as a solid and as well as a liquid which bakes to an opaque. Makin’s brand, however (which also comes in a range of pre-mixed colours) is air-drying (georgeweil.com, n.d.).
Concrete is a familiar building material, as well as being regularly used for ornamentation and sculptures. I found several instructional websites giving information on concrete casting projects for the garden and home (Instructables, 2016), (Moulding/casting concrete bird bath with rhubarb leaves, n.d.).
Other sources show that very small concrete castings are possible, for example to make jewellery (DIY diamond necklace out of concrete, n.d.), (Jim Cotter on cement and concrete in Jewelery, n.d.), (How to make DIY concrete jewellery – DIY style tutorial – Guidecentral ,n.d.).
Art Concrete is a website/resource which gives specific information on applications of concrete to art projects, including very small scale projects (Goss, 2015). Although it gives specific ‘recipes’, because it is a US website I found that some of the materials were not available for small volume purchase in the UK. The author also has a blog which I found useful as a source of inspiration, and for troubleshooting (Goss, 2014)
In most cases a mould will be needed to cast from concrete, and this can be made from a range of materials including plaster of paris, timber, fibreglass, expanded foam, concrete and rubber. However, the mould must be non-porous, so would it have to be sealed, for example with varnish (The Concrete Society, n.d.).
Every website seems to have it’s own suggestions on which brand of cement and mixtures of concrete to use. I found the most valuable information in the chapter on “Ciment fondu casting” in Nick Brook’s book “Moulding and casting” (Brooks, 2005:149-150), which covers cement, sand, mixing ratios as well as information on storage and handling and surface treatments.
Resins and eco-resins:
I was excited by the idea of casing with resins because they can be clear and used to trap items (such as delicate seed pods and flowers). I started by researching the main types of resin:
The first three on the list are toxic and require specialist handling and storage, whilst eco-resin is safe, being made out of natural materials (Nottingham Trent University, n.d.a).
Polyurethane resins are fast curing (de-mould times of an hour or less), and because of their very low viscosity, can be used for bubble-free casting without degassing equipment. They can be used for both clear and coloured translucent castings and pigmented or stone-filled castings (Brooks, 2015: 83). However, polyurethane resins are expensive and extremely volatile, and specialist personal respiratory equipment, specifically designed for use with this type of resin, must be used (Brooks, 2015, 85).
I found a company which supplies a starter kit to produce a silicone mould and polyurethane resin casting (Easy composites, 2015). There is detailed information on their website regarding the specific technical use, safe handling, storage and disposal of these products. The shelf life of polyurethane resin is about 6 months once opened.
Polyester resins are versatile, being available in different transparencies and hardnesses, with a wide range of compatible pigments. They are also relatively cheap. However, methanol is produced during curing, which must be expelled, so good ventilation is needed, along with specialist personal protective equipment (Nottingham Trent University, n.d.b). In addition, polyester resins require a vacuum (degassing equipment) to prevent bubbles forming during the curing process.
Eco-resins (or bio-resins) are a recent introduction, formulated from plant-based derivatives such as sunflower seed oil and soya. They were developed in response to increasing information about the health risks associated with working with polyester, polyurethane and epoxy resins. They do not require toxic labelling and are safe to use in a studio/workshop environment with minimal health and safety concerns (Brooks, 2015: 101). Eco-resins also require specialist degassing equipment to prevent air bubbles during the curing process.
Thinking about the use of resins in this project, both polyester resin and eco resins are unattractive because of specialist degassing equipment required. Epoxy resin is undesirable for reasons of cost and toxicity. Having read the data sheet for polyurethane resin in the starter kit (Easy composites, 2015) I am not convinced that it is suitable to use such a toxic material in the home/domestic environment. I do not have a dedicated studio and most of my work is conducted in the utility room and a back office of the house. In a workshop with a fume cupboard I might be inclined to give it a go, but I don’t feel that I would adequately be able to seal the curing area from the rest of the house, nor adequately ventilate the room.
Jesmonite was invented in 1984 primarily as a construction material. It is a safe alternative to traditional resin systems, consisting of a water-soluble acrylic polymer and calcium carbonate which requires only minimal handling protection in the form of a dust mask and gloves (Brooks, 2005: 71-71).
I found a very good blog post produced as information for CCW (Camberwell, Chelsea and Wimbledon college) foundation students art and design course, which lists general information, tips and hints and suppliers (Foundation 3D, n.d). Nottingham Trent University’s website castingabout.co.uk also gives further details (Nottingham Trent University, n.d.e).
From what I have discovered it does not seem to be possible to cast Jesmonite as a transparent, although as a solid there are many options for colours and effects such as metal and stone fillers (Brooks, 2005:70-71). I have not found any reference to Jesmonite moulding requiring specialised degassing equipment.
I have included these substances together because they are both have culinary applications. I thought they might be safe alternatives to polyester/polyurethane/epoxy resin, because they are transparent (albeit somewhat more stretchy and soft).
I found a very good YouTube video explaining a recipe for a glycerine and gelatine mould (How to make a mold with gelatine and glycerine – part 1, n.d.), and I found that both these ingredients were available in sufficiently large packet sizes to make them viable for moulding. In the follow on video, the glycerine/gelatine mould has been used to successfully make a casting with plaster cloth (a release agent of turtle wax/Vaseline is used). The author cautions against using the mould for paper mache casting because of the high water content of the paper pulp, which she thinks may dissolve/degrade the mould. She also demonstrated that brushing on the glycerine/gelatine was not a suitable method for mould-making (How to make a mold with gelatine and glycerine – part 2, n.d.)
Ice casts are possible in any vessel which is freezer proof. Being clear, there is a possibility of viewing objects trapped within the solid. However there is an obvious disadvantage of the casting becoming liquid at room temperature.
Although primarily used as a mouldmaking material, silicone rubber can be an attractive and versatile casting material. It is flexible, has excellent stretch capabilities, and can be clear, translucent or coloured (Brooks, 2015: 125). It is generally safe to use and can even be obtained in food-safe or skin-safe grades. Nottingham Trent University’s site, castingabout.co.uk gives information on the two types of silicone (condensation and addition cure), with tips and hints on how to use them effectively and pitfalls to avoid (Nottingham Tent University, n.d.c). It appears that some types of silicone require degassing in a vacuum chamber, whilst others do not (Bentley advanced materials, 2017).
Silicone rubber is a flexible, durable material which will set at room temperature with the addition of a catalyst. Release agents are generally not required (Brooks, 2005:63). It comes in a variety of hardnesses, meaning it can be made into objects which are either pliable or firm (Nottingham Tent University, n.d.c). It is an extremely useful and versatile material.
I watched Notting Trent University’s “Introduction to latex” (Nottingham Trent University n.d.d), and a further YouTube video on using liquid latex to make moulds by painting layers and dipping (How to use liquid latex, n.d). It would appear that latex is the forerunner to silicone rubber and they seem to be similar in use and suitability. I understand that latex is only available as an opaque.
Candle making is an obvious application of wax casting, although there are several types of wax which could be used for casting in moulds, including microcrystalline wax, paraffin wax, modelling wax and glass wax. Although wax generally gives off minimal fumes unless overheated, it has a low combustion temperature and goggles and protective clothing are needed to protect from splashes. Colour must be added to wax in it’s melted state. (Brooks, 2005:159-160). For transparent casting, CCW (Camberwell, Chelsea and Wimbledon colleges) suggest using glass wax (Foundation 3D n.d). Glass wax is very brittle and, according to Brooks, is best poured into silicone moulds (Brooks, 2005, 160).
As well as solid casting, hollow wax casts can be created by brushing on layers (Brooks, 2005:162). There are no surface treatments available to protect or colour wax. However, it can be subsequently carved with a knife or shaped whilst warm with a wax modelling tool.
Fabric stiffening with starch or sugar:
I have used a sugar solution in the past to stiffen and mould crocheted lace. The fabric can be formed into sculptures, vases or even boxes. I can imagine that if used with a fine fabric such as butter muslin, it should be possible to sculpt a textured surface from a flat sheet of fabric. I found an instructional webpage on how to make and use a stiffening sugar solution (Curinga, n.d.). Potential disadvantages of sugar solution over starch might be yellowing with age, and the tendency of the fabric to take up moisture and loose stiffness or become sticky and in humid conditions. Laundry starch is readily available as a stiffening agent, although I haven’t used it before.
Fluid acrylic paints/gesso:
Fluid acrylic paints can be used to both colour and stiffen fabric, which can be moulded to shape before it dries (Monk, 2012:10-11). Gesso or acrylic medium can also be used in a similar way (Monk, 2012:8-9, 17).
Moulding with leather:
I found an interesting YouTube video which explained how leather can be wetted and formed over a textured surface (Leather moulding, n.d.). Another video suggested softening the leather first with a solution of water, shampoo and denatured alcohol (Leather upholstery, n.d.). This is a technique which appeals to me because leather can easily be punctured, sewn, or joined to another material, so the moulding could be used as a component multi-media piece.
Softsculpt is a heat formable foam available for purchase in A4 sheets (Painters craft-box, n.d.). The foam is first heated (either in an oven or using an iron), after which, for a short period of time before cooling, impressions can be made by pressing into the foam with 3D objects, or by pressing onto a raised surface. The thin version of Softsculpt may be used for making 3D sculptural forms (Hedley, 2004:87-90). The impressed surfaces may be coloured with paint or permanent markers and may be stitched into (Hedley, 2004: 92).
Bentley advanced materials (2017) Addition-cure silicon rubber. At: http://www.benam.co.uk/products/silicone/ (Accessed 13 January 2017)
Brooks, N. (2015) Advanced mould making and casting. Marlborough. The Crowood press.
Brooks, N. (2005) Mouldmaking and casting. Marlborough. The Crowood press.
Craftmill (n.d.) ModRoc plaster of Paris bandage for modelling. At: http://www.modroc.com/tips-on-using-modroc-modroc-plaster-of-paris-bandage-for-modelling/ (Accessed 10 January 2017)
Curinga, K. (n.d.) How to starch decorator fabric with sugar. At: http://www.ehow.co.uk/how_7630603_stiffen-fabric-sugar.html (Accessed 11 January 2017)
DIY diamond necklace out of concrete (n.d.) [user generated content] Creat. That’s how I made it. At:https://m.youtube.com/watch?v=Hrv-klI2-Wo (Accessed 11 January 2017)
Easy composites (2015) Silicon mould resin casting starter kit. At: http://www.easycomposites.co.uk/#!/starter-kits/silicone-mould-resin-casting-starter-kit.html (Accessed 9 January 2017)
Foundation 3D (n.d) Resin casting. At: http://foundation3d.myblog.arts.ac.uk/resin-casting/ (Accessed 17 January 2017)
Georgeweil.com (n.d.) Model making. At:http://www.georgeweil.com/Craft/Model%20Making/ModelMaking.aspx?Ref=1,80,-1,-1 (Accessed 9 January 2017)
Goss, A. (2014) Art concrete: Questions. At: http://artconcrete.blogspot.co.uk/2014/09/questions.html (Accessed 11 January 2017)
Goss, A. (2015) Art Concrete. At:http://www.makersgallery.com/concrete/index.html (Accessed 11 January 2017)
Hall, J. (2011) Papier-mâché and paper clay. At:http://www.papiermache.co.uk/articles/papier-mache-and-paper-clay/ (Accessed 9 January 2017)
Hedley, G. (2004) Surfaces for stitch. Plastics. Films. Fabric. London. Batsford.
Hobbycraft (n.d.) Clay FAQs at: http://www.hobbycraft.co.uk/pages/clayfaq (Accessed 9 January 2017)
How to make a mold with gelatine and glycerine – part 1 (n.d.) [user generated content]. Creat. Ultimate paper mache. At: https://m.youtube.com/watch?v=MIj_I6mW5QQ (Accessed 11 January 2017)
How to make a mold with gelatine and glycerine – part 2 (n.d.) [user generated content]. Creat. Ultimate paper mache. At:https://m.youtube.com/watch?v=wyxpYWvGU2Q (Accessed 11 January 2017)
How to make DIY concrete jewellery – DIY style tutorial – Guidecentral (n.d.) [user generated content] Creat. Guidecentral English At: https://m.youtube.com/watch?v=bOJ5jQpyUlo (Accessed 11 January 2017)
How to use liquid latex (n.d) [user generated content online] Creat. Richocoarm. At: https://m.youtube.com/watch?ebc=ANyPxKosm2JN-4I1mRI6YScviBsSrrfkzGXT_V_q7K9nD_IRRs8dt40plCfs-7iQjaHmSJROHTskFVi68eOMt0ZgQkyFlzR8tA&v=iYKuJ070MIc (Accessed 9 January 2017)
Instructables (2016) Fun with concrete. Instructables guides. At: http://www.instructables.com/id/DIY-Concrete/ (Accessed 11 January 2017)
Jim Cotter on cement and concrete in Jewelery (n.d.) [user generated content] Creat. Jim Cotter. At: https://m.youtube.com/watch?v=zpU74xQOOAM (Accessed 11 January 2017)
Leather moulding (n.d.) [user generated content] Creat. Nicola Silja. At: https://m.youtube.com/watch?v=pJyqbhliJgE (Accessed 9 January 2017)
Leather upholstry (n.d.) [user generated content] Creat. Cechaflo. At: https://m.youtube.com/watch?v=r1X3sSjfgw4 (Accessed 9 January 017
Nottingham Trent University (n.d.a) Casting techniques. At: http://www.castingabout.co.uk/Casting_Techniques.html (Accessed 9 January 2017)
Nottingham Trent University (n.d.b) Polyester resins. At: http://www.castingabout.co.uk/Polyester_Resins.html (Accessed 9 January 2017)
Nottingham Trent University (n.d.c) Silicon. At: http://www.castingabout.co.uk/Silicones.html (Accessed 9 January 2017)
Nottingham Trent University (n.d.d) Latex. At: http://www.castingabout.co.uk/Latex.html (Accessed 9 January 2017)
Nottingham Trent University (n.d.e) Jesmonite. At: http://www.castingabout.co.uk/Jesmonite.html
Monk, L. (2012) Exploring creative surfaces. D4daisy books Ltd.
Moulding/casting concrete bird bath with rhubarb leaves (n.d.) [user generated content] Creat. Bobo Gaming. At: https://m.youtube.com/watch?v=BsIq_pKjRAc (Accessed 11 January 2017)
Painters craft-box (n.d.) Softsculpt sheets. At: http://www.craft-box.com/Softsculpt_Sheets/p1973248_11305503.aspx
Paperclayart (n.d.) Studio FAQ support. At: http://www.paperclayart.com/151toKids.html (Accessed 9 January 2017)
Paperclay.com (n.d.) Products. At: http://www.paperclay.com/product.htm (Accessed 9 January 2017)
The Concrete Society (n.d.) Casting concrete sculptures. At: http://www.concrete.org.uk/fingertips-nuggets.asp?cmd=display&id=808 (Accessed 11 January 2017)