J – O

Jellutong is a fine, dense but carvable wood from southeast Asia, favoured for traditional carving of puppets because of its lightness in relation to its strength. Obtainable (small strips) from 4D 10x10x600mm £0.61 to  12x34x600 £1.75

Jesmonite is a brand of polymer-modified plaster, supplied in two parts; a hard-setting plaster and an acrylic polymer liquid. The plaster is mixed with the polymer (in place of water) in the usual ratio 2.5-3parts plaster to 1part polymer by weight dependant on the viscosity required for pouring or laminating. If used (like polyester resin) with matting reinforcement a very strong laminate can be made, suitable for large hollow castings. On its own i.e. without matting reinforcement Jesmonite is stronger (less brittle) than plaster for fragile castings and will generally flow better into slender moulds. Pot-life averages about 10-15mins and casts can be safely demoulded in 45-60mins (see ‘Plaster/Polymer’ for further info and alternative systems).

Jesmonite is often touted as a non-toxic, non-flammable, cheaper and generally much more ‘pleasant’ alternative to using resins for durable castings. This may be true if the forms to be cast have sufficient bulk but there’s little comparison with plastic resins for creating a resilient version of a particularly thin or slender form. In this respect Jesmonite remains closer to hard casting plaster in terms of being too brittle for delicate forms. In any case mixed Jesmonite is far too thick to flow into slender mould forms, whereas there are resins for the purpose which are almost water-thin. Another problem with Jesmonite is the persistence of air bubbles in the mix but this is easier to solve if mould surfaces can first be given a brushed-on detail coat before the rest of the mould is filled.

There is a special thickener available for Jesmonite (see Canonbury Arts website, address in ‘Suppliers’ list), also a retarder. Fillers can be added to Jesmonite, but then the ratio of powder to polymer liquid should be 2:1 i.e. more liquid.

jute scrim traditionally used by plasterers as a reinforcement for sculptural or structural plasterwork aka ‘plasterers scrim’, a webbing made from natural jute fibres commonly in rolls 3ins, 6ins or 12ins wide. Weight approx 100g per sq metre. It has a very open weave ensuring that it will ‘wet out’ well (i.e. that it will properly soak through with plaster and not weaken the plaster by trapping air). It performs the same function as glass matting in fibreglass lamination and can be used in place of this when working with Jesmonite or other polymer-modified resin. Medium to coarse grades available Obtainable  Tiranti Price e.g. roll 7.6cm x 100metres £4.75. Also available in sq metres i.e. coarse £1.56 for 1 sq m (2013)

Kapa-line foamboard is a special form of display foamboard manufactured by the German firm Alcan Kapa. Kapa foamboards are distinguished from the cheaper, more common foamboards firstly by having a polyurethane foam interior (as opposed to polystyrene) which is stonger and denser and secondly by the fact that the covering paper can be fairly easily peeled away, to use the foam itself for carving forms or creating surfaces. See ‘Creating surfaces with Kapa-line foamboard’ under ‘surfacing’ in the ‘Materials’ section.

Available 3, 5 and 10mm thicknesses. Easy, smooth carving and sanding of the foam itself. Use any glue (foam is not damaged by solvents) or double-sided tape. Most foamboards from Kapa (e.g. Kapa-graph, etc) can be used in this way, but standard polystyrene-filled foamboard cannot.

Kapa-line foam will also accept coating with catalysed polyester resin, which soaks part-way in, giving it a smooth (when sanded) and much more durable surface.

Obtainable for current prices and suppliers see the ‘Quick view materials info’ page in either ‘constructing’ or ‘surfacing’ in the ‘Materials’ section’

See also ‘Making walls’ parts 1-3, February 2013; ‘Making relief patterning tools using Sculpey’ January 2013.

Kraft board a thinner 2mm (300gsm) version of brown box card, corrugated inside. Ideal for sketch-modelling, very easy to cut and surprisingly strong, also the cheapest around. Obtainable see ‘Quick view materials info’ for ‘constructing’ in the ‘Materials’ section.

lacquer is properly speaking a hard, protective coating which consists of a resin mixed with a quick-evaporating solvent and which may or may not have pigment added. The word is confusing because it has changed over time and is now used liberally by manufacturers. It can be synonymous with ‘varnish’, for example shellac is a lacquer (responsible for the origin of the word, shellac being derived from the lac beetle) but nowadays it’s usually referred to as a varnish. The ‘resin’ used can be naturally obtained such as shellac or tree resin (i.e. the resin of the Chinese ‘Lacquer tree’ Toxicodendron vernicifluum), or it can be nitrocellulose or acrylic base.

lamination building up layers, usually involving the use of a resin and some form of open matting or webbing as in, for example, fibreglass lamination (see also ‘fibreglass’)

LATEX

Natural rubber, not suitable for solid moulds or casts but ideal for thin ‘skins’ (c 1mm successive build-up). Can be layered into/onto most impervious, sealed surfaces and pealed off when dry. Each coat must thoroughly dry before applying the next. It hardens purely by evaporation, which takes time and will not work if layers are much more than 1mm thick. Can be coloured (in the mix) with any water-based pigment. Best paints to use on the surface once dry are either special latex paints, Prosaide/acrylic mix or Humbrol enamels. Latex rubber can also be layered over a simple shape to produce the traditional ‘sock’ mould form but expect some distortion from this method.

Works best if applied to an absorbent surface, but one it can easily detach from i.e. plaster ideal choice. Ammonia as preservative. Can be thickened by adding talc, plain flour or even wallpaper paste (mixed as per directions first and then added) without affecting the drying time. Special latex thickener can also be bought (average one drop of thickener per 1g of latex).

Use as supplied, no mixing needed. Not compatible with Vaseline; 10% shrinkage overall; fairly good detail reproduction and high tear strength; no health&safety issues. Obtainable see entry in ‘Quick view comparisons of casting materials’ in the ‘Materials’ section.

Prosaide obtainable from Guru Makeup Emporium www.gurumakeupemporium.com £10.95 for 2oz, also www.charlesfox.co.uk or (recommended 2013) www.henna-boy.co.uk £9.50 for 150ml, £14.00 for 250ml.

Lazertran Silk transfer paper. A copy paper specially designed for transferring an image onto another surface. Designed for silk but works well on metal. Artwork must be strong black, and copied onto transfer paper using ‘colourprint’ setting on commercial copier (inkjet not sufficient as it needs a proper solid toner). Image transferred using heat (iron or oven). Obtainable see ‘Quick view materials info’ under ‘metalwork’ in the ‘Materials’ section.

library life is the term applied to moulds which means how long they will last (whether used repeatedly or even stored unused). It is not necessarily an indication of the number of casts that can be made from them.

life casting making a mould ‘from life’ i.e. usually a human subject, using a fast-setting and skin-friendly material, from which an immediate cast is made, usually in plaster

lighter fluid distilled from petroleum, usually described on the can as ‘solvent naphtha (petroleum) light aliph’ Uses removes oil or grease-based stains including tar, solvent-based inks and some soft glues (i.e. good for removing residues left from tape or labels). Safety data highly flammable; harmful if swallowed or inhaled in concentration; can cause skin irritation. Obtainable most newsagents or supermarkets in 133ml cans e.g. Ronsonol c. £1.70, or from £-shops

linear shrinkage the amount of shrinkage measured across a surface, given as a percentage of the whole

lost wax casting also known as ‘investment’ casting, is a traditional process whereby the sculpture is modelled in wax and then completely covered with a clay shell, called the investment. When this clay shell is heated up the wax liquefies and can be poured out leaving a void which is an exact copy of the original form. The clay investment continues to be fired until it is hard enough to be filled with metal. Once filled the whole investment is broken away leaving the original form now in metal.

maquette meaning ‘model’. A smaller version made as a visual test. The word is most commonly used in figurative sculpture.

Material-Archiv Swiss online database (in German) of architectural, design and industrial materials www.materialarchiv.ch

MDF ‘medium density fibreboard’. A reconstituted form of wood available in sheet form, made from finely ground sawdust which is mixed with binding agents and pressed into sheets. It is very popular as a constructional material because of its price; its rigidity (better than plywood in maintaining flatness); ease of cutting (absence of grain) and surface smoothness. It is generally heavier than natural wood or plywood. MDF is standard stock in building supply or home hardware stores such as Wickes or B&Q. Usually the thinnest available from these is 6mm and the thickest 25mm. For current prices at B&Q and Wickes refer to ‘Quick view materials info’ in ‘constructing’ in the ‘Materials’ section

Much thinner versions are available (though these are generally more expensive than the standard thicker) i.e. 2.5mm from Jackson’s Art Supplies (jacksonart.com) or 1, 1.5, 2, 3, 4mm and so on at 4D modelshop. Refer to the ‘Quick view materials info’ for current prices.

MDF can be good material for laser-cutting, though there is also a special ‘laser grade’ MDF available (4D).

MEKP (methyl ethyl ketone peroxide) best known in a diluted form as the catalyst for polyester resin (diluted 30-60%, dissolved in e.g. dimethyl phthalate). Dangerous material! Very corrosive and highly flammable, in higher concentrations becomes explosive. Risk of blindness in contact with eyes. MEKP hardener has a shelf life normally between 1-2 years if stored in a cool place out of sunlight.

METAL

See individual entries i.e. brass, aluminium, wire, ‘cold metal casting’ etc.

metal construction blocks are rectangular pieces of solid steel (or clean metal of similar weight) used for assisting the gluing of edges or right-angles in small or medium-sized construction work. They are also useful as guiding ‘stops’ i.e. to glue against when joining long strips to each other. These ‘tools’ are not available to buy in tool shops, which is surprising .. and unfortunate! .. considering they can become the most indispensable of all. There are just a few requirements of these simple helpers: they must be clean, smooth and undamaged metal; most, though not necessarily all their faces should form reliable right-angles; corners should be ‘sharp’ rather than rounded; they must be heavy enough to stay firmly in place when pushed against but not top-heavy.

They are not difficult to find as ‘offcuts’ though and need not be expensive. For example, the online metal retailer Metal Mania www.metalmaniauk.com stocks different blocks of 250mm length (the smallest length in stock) in ‘bright flat mild steel’. A block with width 20mm, height 40mm (good, stable proportions) will currently (2013) cost £7.48 (weight 1.573kg). A 25mm square bar of the same length is £5.32 (weight 1.25kg). Delivery costs £9.50 for items under 4kg in weight. Website prices include VAT.

8/2013 ordered 250x20x40 bar ‘bright flat mild steel’ from Metal Mania. Took a few days to arrive. Catalogue cost £7.48, final cost after delivery and VAT £13.98. I’ve found these proportions particularly suited for the work I do. The 20mm wide base is just wide enough in relation to its 40mm height to make it properly stable when pushed against. The 40mm height is also just enough to establish a guiding right-angle for work up to around 150mm high. Having the 250mm length is particularly useful when joining long strips. 

metallic paints are composed of fine metal or metal-look powder in place of pigment. The other ingredients are the usual ones for the paint type, hence the fact that there are metallic versions for most paints whether water-based or spirit-based. A common substitute for actual metal powder in these paints is mica.

A good indication of some of the varieties of metallic paints available can be found by looking in the catalogues of gilding & restoration specialists such as Wrights of Lymm http://www.stonehouses.co.uk/product_list.php?id=505

E.g. Roberson’s Acrylic Liquid Metal (wide range) 30ml £2.95 or Polyvine 50ml £3.25 (2013)

methylated spirits is known in the US as ‘denatured alcohol’ which better conveys the fact that it is ethanol which has been rendered undrinkable by adding methanol (c. 10%), hence the UK name. The usual mauve/purple colour is just a dye added to identify it.

Uses will dissolve or thin shellac or shellac-based varnishes (hard shellac is dissolved in it to create the varnish); can be used to thin epoxy resin; used as a fuel for small burners; will help in removal of ink stains and permanent markers from non-porous surfaces such as metal, glass, plastic .. generally a good cleaner for hard surfaces; as a preservative for biological specimens; to clean/disinfect skin before surgery; window washing (streak-free polishing with a 50-50 mix with distilled water)

Safety data highly flammable; dangerous by ingestion; harmful by inhalation and skin contact (will de-fat skin and strip it of moisture) Obtainable refer to ‘Solvents and thinners’ in the ‘Materials’ section for current suppliers and prices.

microcrystalline wax is a cohesive and flexible wax (more elastic than paraffin wax) which is a common ingredient nowadays in modelling or casting wax formulations. The melting point is 71°C

micron there are 1,000 microns to 1 millimetre

Milliput is a 2-part, very hard-setting epoxy modelling putty, available in two fineness grades and a few different colours. It is most suitable for small, delicate work. ‘Standard’ Milliput is a light yellow/grey colour when mixed while the extra-fine grade is white. When equal amounts of both parts are thoroughly blended together (until the colour is uniform) the putty begins to harden. It remains easy to model for around 40mins, then slowly hardens (but see below). It will stick annoyingly to fingers, but can be smoothed or even thinned with water. Vaseline on the fingers is effective in helping fine smoothing (methylated spirits can also be used).  It will stick well to most surfaces in it’s soft state and even serves well as a gap-filling ‘cement’ especially if it’s used straight after blending when it’s still sticky. It is often used in the restoration of antiques and art objects because of it’s high adherence and strength when cured. When hard (after 3-4 hours) it is very durable but can be easily sanded and tooled (i.e. sawn, drilled), even carved with a scalpel. There is no noticeable shrinkage. According to the manufacturer it has a shelf life of c. 2yrs if stored cool, dry, sealed in polythene bags provided.. but see notes below. Obtainable most good art or hobby shops, Tiranti, 4D Price (2013) c.£2.28-£5.06 (Tiranti) per 113g packet dependant on type (ranging from standard to fine grade and colours e.g. terracotta, black). See ‘Quick view materials info’ for ‘modelling’ in the ‘Materials’ section for current suppliers and prices.

mitre the 45degree angle given to an edge, usually in order to join with a similarly angled piece to form a right-angled structure i.e. at the corner of a picture frame.
Model-making technique (i.e. for building up door or window frames using thin strips of wood or plastic). Move round in one direction starting from bottom corner; can use squares on cutting mat as rference to get 45degree angle; cut at slant to improve fit .. read more in post ‘Making walls – Part 3’ February 2013

modeller’s plywood an ultra-thin type of plywood (composed of 2 or more thinly sandwiched layers). There are plywoods as thin as 0.4mm. See entry in ‘Quick view materials info’ for ‘constructing’ in the ‘Materials’ section.

modelling wax .. see ‘Wax’

‘mono-mould’ method is the method of creating a form by means of one-off casting. The ‘mould’ in which the form is created can either be soft clay in which a negative shape is pressed or hollowed out, or a construction in a semi-rigid material, or a negative shape can be carved out of a rigid material. This void is then filled to create a positive version. It takes advantage of the fact that certain forms are easier to create in negative i.e. as voids rather than solids.

mother mould not the mould itself but the casing which keeps the softer silicone parts of a mould in the right shape. Can also be referred to as the ‘mould jacket’. It is made, either as one part or separable parts (depending on the complexity of the form) directly onto the silicone once it has cured on the prototype. It is important that the mother mould pieces will separate fairly easily from the silicone ones but fit them exactly. Mother moulds are commonly made in plaster, or plaster/polymer with scrim reinforcement, or fibreglass. There are also other (though much more expensive) resin or rubber-based materials for making mother moulds available from the US firm Smooth-On.

mouldmaker’s soap see ‘release agents’

Mountboard is a specific form of card, roughly 1.4mm thick and sold in A1 size, designed for easy cutting (usually passepartouts for framing pictures under glass). White or black/white sided are commonly used for model-making but many other colours are available (e.g. Daler-Rowney ‘Studland’ brand most commonly used). 1.4mm (1,400 microns) is the standard but some thinner versions exist. Obtainable almost all art/graphics shops Price varies £3-5 per A1 sheet

MSDS stands for ‘Material safety data sheet’, an official account of the properties of a product with regard to health & safety, which the manufacturer is required to make available. There doesn’t appear to be the same obligation with regard to suppliers, although most good outlets include them on their websites. They are never supplied in print form with the product anymore, and often have to be sought on the manufacturer’s website, or even by having to contact the manufacturer! These are not the same as TDS or ‘Technical data sheets’ which list (often more useful) information relevant to how the product can be used such as weight, strength and mixing guidelines. MSDS sheets do not have a strictly standardised appearance and can vary a great deal (possibly in accordance with the laws of the region) in terms of what they actually disclose and .. ridiculous really .. how clearly they communicate health concerns! Nevertheless, for want of anything better, they should always be consulted.

natches or ‘mould natches’ is a special term to describe the positive and negative shapes made between two interlocking mould halves to locate them and keep them securely in position. When the first mould half is being made depressions can be pushed in the clay dividing wall (i.e. using the smooth, round end of a paintbrush) which are then filled by the silicone rubber. These come out as positives in the cured mould half and the second mould half covers these to make the corresponding negative shapes once more.

New Blades is an annual summer exhibition of graduate work from the model-making BA degree courses around the country. It is a good opportunity to see a wide variety of making-skills and models/objects range from architectural, product models, interactive exhibition models to animations, puppets, creature designs and costumes. Work can be seen on this flickr site http://www.flickr.com/photos/newblades/

nitrile rubber gloves are more resistant than latex, especially to oils and fuels, hence a better choice when working with resins or solvents. They have a little less flexibility than latex but are more puncture-resistant

non-slump as in ‘non-drip’ meaning that a thick mixture can be applied to even a vertical surface without shifting downwards. Many liquid materials such as silicone rubber, latex, polyester resin or Jesmonite.. to name just a few.. have special additives available to change their consistency for this or similar purposes. These are sometimes called ‘thixotropic’ agents (often explained wrongly as ‘thickening agents’) because thixotropic denotes .. not that something is just ‘thick’ .. but the ability of a gel-like material to keep its form against gravity.

Obeche wood A soft but firm wood, ideal for small-scale work. Easy to cut, not brittle (0.8 sheet is surprisingly bendable up to a point), stronger than balsa. Soft, fine grain will not ‘divert’ knife blade much, but a bit more so than bass wood. Visually subtle grain (though more grain than bass wood), stains very well. Most suitable in sheet form (i.e. for panelling, floorboards) but also available in thicker pre-cut strips. Obtainable in 0.8 – 6.4mm sheet thicknesses (10x90cm size). Obeche is a tropical African tree, prized for lack of splinters and resin (used in sauna interiors). Conservation status ‘Least Concern’ (2012).

Distributed by www.tasmaproducts.co.uk under the ‘Orbit’ trademark.
Obtainable see ‘Quick view materials info’ for ‘constructing’ in the ‘Materials’ section for current suppliers and prices.

oil paint as a blanket term for any paint which uses a drying oil as its binder, but most familiar as artists’ oil colours. Colour more intense; much more workable i.e. re wet blending; doesn’t change tone with drying. Long drying time (sometimes weeks or even months depending on thickness); proper ground needed (not too absorbent). Suitable for colouring polyester resin, also Platsil silicones (mixed in, not for surface painting).

Recipe/- pigment+cold-pressed linseed oil (2% beeswax makes thicker). Boiled linseed oil for faster drying, tougher paint. Cheapest linseed oil (boiled or raw) from Bartoline £2.30 per 500ml (2012). Thinning paint with linseed oil

one-off meaning unique, a single example as opposed to a series