Materials needed -
* Alginate
* Cold Water
* Fine casting plaster
* x2 Large mixing bowls
* Plaster bandages
* Wood Panel — Replicaties width of the canvas
Mixing Ratio -
1:3 Approximately 1 part alginate power to 3 parts water, ie. 300ml water to 100g powder. Less water causes the alginate to firm up quicker, resulting in a set mix... resembling that of cottage cheese as I found out in my first run through!
For the most part my castings were to be externalised rather than being set into a container, this meant I had to include plaster bandages as a liable variable within this method.
Chronological Methodology -
> Prepare the equipment and materials needed.
> Using a measuring jug or container, pour the required amount of water into the mixing bowl. This can be measured precisely or 'eye-balled' if the ratio seems adequate to you then proceed.
> Measure the correct ratio of alginate needed in a seperate container.
> Empty the alginate powder on top of the water, the powder will change into a striking pink; you have just two minutes to mix the alginate before it is completely cured. Preferably the mixture should be rendered well after 40 seconds.
> Once the mixture is ready, pour over the desired moulding subject, in this case it was a hand. Once poured over the hand and the mixture is starting to cure, use all of what you can to secure any holes that may be present within your mould.
> Secure 4-5 (depending on the size of the subjects hand) plaster bandages. You can do this by dunking the bandage into a contsainer full of water, gliding your fingers quickly across to remove excess water and then securing to the mould. 4-5 is the number I had used over my moulds, though this may differ upon subject and caution. The plaster bandages enables you to eradicate any potential leakages of the plaster which will later be added to the mould.
> After 5 minutes the alginate will be fully cured. The subject is to then gently wiggle and pry away from the alginate, be careful not to rush this process as this may result in the mould collapsing or becoming damaged. Please note not to panic during this process, the alginate can feel somewhat suffocating over the hand given its suction but this is perfectly normal.
> Upon the release of the subject, start mixing the plaster. The plaster can be mixed through 'eye balling' the consistency. Gather a mound of plaster in your hands and gently sift through into the water, repeat this process a number of times till 'islands' are no longer present and floating (islands are dry clumps of plaster) Mix the plaster with your hands and pour into the alginate mould.
> For further reassurance you can choose to seal the mould further with more plaster bandages.
> Gently shake and knock the mould as to stop air bubbles from harrowing within the corners of the mould.
> After 15 minutes to half an hour the fine casting plaster should be cured within the mould. This can differ depending on the depth of the mould and the temperature of the environment. Waiting a longer period of time however is more wise to do so, as if the plaster is not fully cured this can result in the cast to crumble or give way. Following the curing of the plaster, grab a scalpol or box cutter and begin to cut away the alginate. Proceed with caution as to not damage the cast or yourself.
> If you plan on painting your casting (acrylic/ varnish) please allow your casting to dry for one week in a warm room. If you were to paint or seal the casting before the recommended time frame, the moisture will still continue to evaporate from the plaster which will then cause the painted surface to spoil.
My Experience -
I found working with alginate to be both challenging and fascinating. The first attempt I and Graham (casting technician) had made resulted in a cottage cheese like consistency due to having the wrong ratio of alginate to water, the second resulted in the ratio being off by a margin of water, though the mix was still useable, and we created a mould from it. Unfortunately the mould assumed the cottage cheese texture, resulting in the plaster cast to be something of an organic barnacle-esc texture, rather than a perfect rendition of the hand. On the other hand so to speak; the test casting could be used in another composition with expanding foam, connoting towards elements of the ocean.
Having learned from our misjudgment of ratios, we began to experiment with varied amounts of alginate to water, finally grasping exemplar consistency and beginning the casting process. Though the methodology of this medium had presented a number of complications, I found the process to be therapeutic and rewarding. Being one of the subjects for a mould was quite the experience given the suction of the alginate, it was rather hard to release oneself from the mould! Upon photographing and observing the nature of these casts, I am truly blown away by the texture inhabited across them, each crevice, indentation and line of the skin has been impressed over the surface of the plaster and I am content with the final product.
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