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Plasters and Mouldmaking ...Life casting kits, alginate moulding kits, statuette- and statue-making etc. ... Our Price: £1.99 Modelling Materials for sale Plaster Of Paris 1kg ...
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Synonyms: alginic acid sodium salt, sodium polymannuronate, algin, alginate KMF, algiline, amnucol, antimigrant C45, cecalgine TBV, Dadrid QH, Dariloid QH, Halltex, kelco gel LV, kelgin LV, kelgum, kelset, keltex, keltone, manucol, manutex, minus, monason, nouralgine, pectagline, proctin, protanal, protatek, snow algin H, stipine, tagat, tragaya, further trade names Kromogel Chromogel
Impression Moulding Chromatic Alginate - is 4.05KG (9 PACKS) of Chromatic Colour Change Dental Alginate ... 4 x 10kg of plaster..... Alginate. ...
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Life casting kits and alginate moulding kits to create keepsake ...Life casting kits and alginate moulding kits to create keepsake statues of hands and ... Casting Plaster - 50 lb.(22.70 kg) bag. Casting Plaster - 50 lb. ...
Moulding:... Moulding -Casting Plaster 2.5KG, Wax for Candles - 1KG - 2.5KG, and - all at low prices.
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Life casting kits and alginate moulding kits to create keepsake ...(2 kg) box. Alginate moulding powder. This is a safe moulding compound that duplicates every detail of any hand, foot or of almost any other object. Price: ...
Moulding and Casting Materials All prices exclude VAT. On This Page : Liquid Moulding Latex, Plaster, Mod Roc, Art-Mache, ... Moulding Alginate. For moulding complete objects. ...
Green & Stone Art Materials All prices are UK pounds and include VAT. [Listed in green] ... Gedeo Silicone Moulding paste, Alginate, Resin Plaster and Crystal Resin, Rubber latex ...
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MARAGON - ARTS & CRAFTS
MARAGON - ARTS & CRAFTS
Casting, Moulding & Modelling - Materials & Kits
Casting, Moulding & Modelling - Materials & Kits
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All About Alginate
Alginate (pronounced al'jinate) is a flexible mould- and impression-making material; a gel is formed by
mixing the alginate powder with water. Alginate powder is manufactured from kelp - a variety of seaweed;
it is usually supplied in a foil sachet of either a 450g (1lb) or 900g weight. Alginate is widely used in
reproducing small to medium-size objects, figurines, etc. as well as patterns and mouldings in plaster and
timber, particularly in restoration work. Dental (clinical) grade alginate is completely safe in direct contact
with the skin (it is used for making dental impressions, etc.) and it sets quite rapidly - so it is also the preferred
material for life-casting (making moulds of the face, body, feet and hands, etc.). ‘Chromatic alginate' is so-
called because it changes colour according to the phase it has reached after mixing and chromatic dental
alginate is the material assumed in these instructions. In common with RTV silicone and latex, alginate is
capable of capturing extremely fine detail - even down to the pores of the skin. Work on both inanimate
subjects and life-casting are described below. Alginate has several advantages over other materials:-
i) It sets very quickly and can be separated from the subject within 3 to 4 minutes of application.
ii) It is clean, economic, easy to apply and needs no special skill or tools, additives, etc.
iii) No release agent is required against non-porous surfaces, the mould detaches from the original as it
sets - although vaseline should be applied to avoid trapping strong hair growth, cloth fibres, etc. when used
in life-casting, and a sealer such as shellac should be used to seal porous surfaces, e.g. clay, card, etc.
Its drawbacks are:-
i) It is quite a floppy material once set and large, unsupported areas tend to sag and sometimes tear*; this
often dictates the method used to make the mould (see below). *Serious tears can be repaired with
supaglue.
ii) Alginate moulds are not particularly durable, and need using within 24 - 48 hours unless kept in humid conditions; however, using the mould soon after forming doesn't normally present any problems.
Methods
There are two ways of forming an alginate mould:-
i) Immersion. This is where the gel is poured into a suitable container and the object is immersed while the gel sets; the container can be a jug, a bowl, a sandwich box or even a plastic bag.
ii) Spread-application. A thicker mix is used than for the immersion technique, and the alginate is spread on to the object -
usually by hand - and sets into a rubbery layer which can be peeled away after a few minutes.
Immersion uses more mixture - albeit slightly weaker - and is generally most-suited for small to medium-sized, free-standing objects. Moulds formed by spread application, however, can be very floppy and need support or a backing to preserve their shape - this usually has to be done before the mould is removed, but the choice of methods is usually fairly obvious. Depending on the shape and size of the original, either of these techniques may be used for making moulds of solid objects or in life-casting.
There are occasions when the topology of the original would make it impracticable to de-mould the alginate in one piece; however, by slicing through the set alginate (or even carefully tearing it where a sharp blade is not appropriate) -
then matching up and strapping the sections together, it is possible to make moulds and produce castings
from the most complicated originals; seam lines in the finishing castings can be easily be smoothed over
later. An alternative is to mould and cast projections, extended limbs, etc., separately - which makes it easier to introduce reinforcement (dowels or wire) into slender areas or vulnerable points. Note that cuts and tears in alginate can also be repaired with supaglue.
Preparation and Technique
Note: The following general instructions apply to normal-setting (regular-set) alginate. The fast-setting alginate sets in a little less than half the times shown here. If using alginate for making moulds of small children's feet and hands, etc., similar setting times can be achieved by using warm or tepid water with normal-setting alginate - the warmer water is likely to be less disagreeable for the subject.
You will need to make all the usual preparations for casting work, including plenty of sheeting and
newspaper, etc. on floors and work surfaces, a clean water supply and suitable mixing bowl and tools, etc,
and some towels, and overalls or old clothes. According to which of the two methods you have selected
you will need a suitable container or bag (to hold the gel for immersion-moulds) or suitable spreaders (the
back of a table knife, plastic card, etc.) for spread-applications. If you are going to reinforce or provide a
backing to a spread-mould in-situ using modroc, etc., you will need to have the necessary material made
ready and cut to shape before you start. All the stage times quoted assume the water is at 18°C; using
water 5°C lower may double the times depending on air temperature, warmth of the subject, etc., but the
retarding agent can also be used to extend times. However warmer water is often preferable when working
with babies - typically, water at blood temperature (37°C) will reduce the setting time to under one minute -
so the whole procedure is much more condensed and does take a little practice.
The powder to water ratio for immersion moulding is around 35:100 by weight; this roughly equates to one cup of loose powder to one cup of water - but, for consistent results, work by weight whenever possible. For spread-applications, a stiffer mix is needed - usually 50:100. A typical 450g packet of alginate yields around 1.3 litres of gel when mixed 40:100. A small trial beforehand is always a good idea using a kitchen scales for measuring out the powder, e.g. mix 40g of powder with 100ml water (100ml of water weighs 100g).
Thoroughly loosen the powder in a separate bowl beforehand. The mixing bowl itself should hold about 4x
the volume of water you are going to use - this will ensure plenty of room for mixing the paste - a food-
mixer can be used for quicker results. (The alginate will peel off any smooth-sided container once set - and
it's also easier to clean it off hands and tools then). Sprinkle the powder on to the water and stir in
thoroughly with a table knife, scraping down the sides of the container, etc. Mixing should take about 50
seconds only in which time the paste will turn from purple to pink and the lumps will have mostly
disappeared.
Tap the sides of the container quite firmly before pouring to help release air bubbles.
Moulds for small objects can be made by pouring the paste into a polythene bag or a narrow container and then immersing the object/part,
wriggling and moving it around for a few seconds to eliminate air, etc, then holding still for 2 - 3 minutes. Try to devise the container and arrange the subject so that there is at least a 6mm covering of gel at any point.
For larger surfaces, spread
the paste evenly on to the subject with the back of a table knife, a suitable trowel, or a plastic card - or just use your bare hands - generally working upwards and outwards to give an all-over coating as
quickly as possible, then immediately repeat to give an even and smooth finish. Avoid thinning/feathering out at the edges. Again, try to ensure that there is at least a 6mm covering of gel across the whole surface/profile -
lesser thicknesses dry too quickly and will be difficult to remove, particularly on solid or rigid
materials.
Finish work when the paste starts to turn white - the mix is then beginning to set and becomes grainy and difficult to use. The whole application should be completed within 60 - 90 seconds.
The set gel can be removed from the subject at a little under 4 minutes, using a gentle
manipulative and soft pulling action to ensure gradual and even separation. Setting may take a few minutes longer on solid surfaces.
Note: On vertical and overhead surfaces the alginate will detach under its own weight towards the end of the setting period, so support must be given to the mould to prevent it falling away or tearing.
The mould will tend to dry out and deteriorate within a few hours, so start the casting fairly soon
after forming - or keep it under a moist wrap (but not wet) with some appropriate extra support if
the casting work has to be delayed. Depending on the particular product the alginate may turn back to pink or remain white after setting; dab off any excess
moisture before (re-)use.
Decorative Mouldings and Ornaments.
Hessian, etc. can be laid into the wet plaster as reinforcement - this is particularly advisable when casting long sections of cornice, etc., but may not be necessary on small or deep sections, small plaques, etc. For large sections it may be feasible to cast just a thin, outer shell; conversely, for small, free-standing objects an immersion mould is often preferable - these alternative methods are described in ‘Life-casting’ below. Moulds that have little or no undercut can be often be used several times if a light baby oil is applied to the alginate between castings. *The backing strip or board often can be shaped or profiled to reduce the amount of alginate needed, particularly on long mouldings, etc. (alginate is surprisingly heavy).
Life-casting
Shell Casts: This is the usual method for making head, torso, and limb casts, etc. The cast is built up in several layers,
starting off with an initial contact layer of plaster which is washed/bathed over the inside of the mould, then
two or three layers incorporating hessian or fabric strips are gradually added (in much the same way as
fibreglass work), with the finished shell being perhaps 10mm thick. Whole-body casts can be made by
simply joining a back and a front cast together.