Category Archives: Project 2

Part 3 – Stages 2&3, Project 2 – Casting the internal space of a vessel

22 February 2017

Stages 2&3, Project 2 – Casting the internal space
From my technical research, I ruled out the use of resins due to their toxicity and/or the need to use a degassing chamber (to which I do not have access).
Jesmoite was initially attractive, being available in many different finishes, however it is relatively expensive to buy and only available in opaques, so I ruled it out on that basis. Concrete (also opaque) appealed because of it’s surface texture and ubiquity as an architectural material. Gelatine/glycerine was attractive because of it’s non-toxicity and transparency. Similarly, glass wax. Silicone is probably the most versatile of the liquid casting materials being available in different hardnesses, finishes and transparencies. Plaster is cheap, and readily available. However, all these substances are liquids, which require a mould.  

I had initially intended to cast using the following materials:

  • Plaster of Paris (because of it’s cheapness, low toxicity and versatility)
  • Ciment fondu (because of it’s interesting texture, ability to capture detail and make small castings)
  • Glass wax (as an alternative to resin, because it is clear and can be used to encapsulate objects and it is much safer to use and handle)

Although I purchased some of each of these materials, I ran out of time, so decided to concentrate on different castings using just the plaster of Paris.


Plaster of Paris:

SAMPLE 1: Casting the inside of a sewn bag
Intrigued by a cast sample by fellow OCA student Nina O’Connor (O’Connor, 2016), I had already done some sketchbook work, thinking how I could relate this to my studies in Part 1, project 2, exercise 4, and how I might develop the idea to make it my own (see sketchbook page 53). These ideas, however had to be put on hold, because I experienced technical difficulties (as explained below):
The plastic bag shown below was marked up ready for stitching. The idea was that the squares would be stitched with a sewing machine to prevent plaster from running into these areas, and the resulting cast would be like a cushion with square holes or “windows”.
However, when I poured the liquid plaster into the bag, it ran through the stitching, both penetrating some of the squares which I had intended as voids, and also escaping from the sewn bottom of the bag. I was unprepared for this scenario, and the plaster went everywhere – it was a complete mess! Eventually, the plaster started to solidify, and some at least was retained inside the bag. 
When the plaster was solid and reasonably hard, I tried to remove the bag. Because of the penetration through the stitching and because of the thinness/fragility of the bridges, they all broke and I was left with two separate pieces of plaster (see below):
Despite not achieving the intended outcome, I quite like these two matching “pillars”, because they reflect the shape and creases in the bag. I like the proportions of them being the same length yet different widths and I can image joining them together with wire whilst leaving a gap in the middle (as shown in the way I have arranged them for this photo).
I also repeated the experiment using a heavy duty reusable plastic supermarket bag (see below):
The result was the same, with the plaster running straight through the sewing machine stitching. At this point, I looked back at Nina’s blog and realised that rather than using plaster of Paris, she had used an artex finishing plaster which “was coarser, and which mixed to a stiff consistency”. This explained why my castings had been unsuccessful; plaster of Paris was too fine-grained and runny to be continued in the casting pouch.
SAMPLE 2: Moulding the internal surface of a balloon
The method for these samples came from a series of detailed Youtube videos (Reynoldson, n.d.). I filled a punch balloon with plaster of Paris, using the methods for plaster mixing and balloon filling which were described in the videos. The creative part comes with tying or clamping to give the internal spaces interesting shapes.
Sample 2a)

The photograph above shows my first sample in progress, complete with clamps and elastic bands. In addition, I used an offcut of routed decking timber behind the clamp, which gave a striated impression in the area of contact (see below). An old pair of tights were used over the balloon to help give grip when clamping and tying.
The different types of ligature material and clamping gave unique shapes. It was possible to either make complete holes or round depressions depending how tightly the clamps were used.
The finished result reminded me very much of the sculptures of Henry Moore. I have referred to these in my sketchbook, together with reference to other artists (see pages 55-59). My sketchbook also includes a number of observational drawings, focussing on different features of the sculptures and using different media. 
Some photos of the sample in different configurations are shown below:
I chose not to finish my samples, although they could be sanded, the small air bubbles could be filled, and they could be painted or given other surface finishes, such as varnish or metallic leaf.
Sample 2b)
A similar sample to 2a), but using string and twine instead of rubber bands as ligatures, and using a grouting tool to make an impression. In the second photo the impression from the edge of the grouting tool can be clearly seen.
I like how samples 2a) and 2b) appear very different in character, with 2b) seeming much more anthropomorphic (perhaps foetal?). I’m sure that these could be developed further with interesting surface finishes and colour/paint effects.
SAMPLE 3: Cast of the inside of a freezer bag resting against a laundry basket
I simply poured the liquid plaster into a freezer bag, tied the top closed, then rested the sample against the side of a plastic laundry basket to make an impression of the surface as the plaster dried.
the finished result was much smoother than some of my other castings and the detail of the mesh of the laundry basket and the gusset of the bag were very well replicated (see below):

SAMPLE 4: Casting of a piece of knitted fabric
this was a piece of fabric from the jumper which I had used for sample 15 of project 1. The knitting contained a stocking stitch and cable sections.
First I placed the piece of knitting in a glass bowl (being aware that some plaster would penetrate through the fabric, I had lined the bowl with plastic sheet) – see below:
I poured the liquid plaster over the knitting and allowed it to just set. At this point I removed the sample from the bowl and peeled off the knitted fabric and plastic (had I left it until the plaster was completely set, it would have been impossible to remove).
I am really pleased with the finished sample. The impression of the textured knitted fabric is excellent, however there are some of the woollen fibres left embedded within the plaster. this may or may not be desirable, depending on he application.

SAMPLE 5: Cast of a burlap-lined bag
I used a strong metallic-plastic coffee bag for this sample, which I lined with a strip of burlap fabric (see below)
I chose this bag because it was stiff enough to stay upright when filled with plaster. I allowed extra burlap, so that I could tug at it to easily remove it after the plaster had just set.
The result was a highly textured block, which also included embedded fibres from the burlap (see below)
I like the contrast between the smooth edges of the cast which were in contact with the coffee bag and those areas which were lines with the burlap and which appear sack-like.
SAMPLE 6: Casting the negative space of a balloon-filled container
I came to this ideas as a result of some sketchbook work (see “the squashed object, p.46). I was interested in deformed shapes and negative spaces which result from cramming objects into a confined space. I realised that I couldn’t use air-filled balloons because they would float in liquid plaster, and I thought about the smaller, water-filled balloons which seemed ideal.
To make my mould, I took a square cake tin and placed as many water-filled balloon into the space as I could (see below). I lined the tin with some cling film to make removal of the plaster cast easier.
I then made up my liquid casting plaster and poured it into the negative spaces.
Once the plaster was just set, I attempted bursting the balloons (over a sink because they were water-filled!) and removing the cast from the tin. My first attempt was a disaster (see below):
The walls of the cast were very thin and fragile and the plaster was not sufficiently set. It made a horrible mess, but there was sufficient interest for me to try again. I repeated the whole procedure, except this time I left the plaster to set until it was much harder. Removing the balloons was easy, but it was almost impossible to get he cast out of the metal tin. Eventually I managed, but I realised that the tin had a rim which was preventing the cast from sliding out smoothly. In future the tin will need to be lined with inserts to make the sides straight!
After all my efforts, I was rewarded with a fabulous sample (see below):
There is an interesting honeycomb effect made by the negative space with breakthrough “holes” wherever the balloons have been touching. The shadows that the walls of plaster and these holes create is another point of interest. I have made a couple of observational sketches on page 54 of my sketchbook.
There is not as much deformity of the balloon shapes as I would have liked, and I thought that a way of getting round this in future might be to fill the balloons with polystyrene beads (similar to those used in bean-bags). These would make the balloons deformable, whilst being possible to remove once casting was complete.
SAMPLE 7: Moulding the internal surface of a fabric tube (old tights)
The samples which I had made using punch balloons (samples 2a) and 2b)), were similar in size and shape, and constrained by the roundness and size of the balloons. I considered using long balloons as an alternative, but I couldn’t find a funnel or bottle top small enough to fit into the balloon opening (to enable me to fill it with the liquid plaster). So the tights were the alternative that I came up with. I knew from my experience that at least some of the plaster was going to flow through the mesh of the fabric (I hoped some would be retained). 
I placed the tights into a plastic bag before filling, to collect overspills and plaster which seeped through the mesh. As the plaster started to dry and harden, I tied ligatures of string to shape the casting. The result was a series of four globular castings, reflecting the shapes of the ties and a subtle surface texture due to the mesh of the nylon (see below):
Although I attempted to removed the nylon mesh before the plaster was fully dry, it tended to tear and some of the fabric was left inside the crevices (see below):
It reminded me very much of the plaster casts of American artist Erin Tucker (Tucker, n.d.). I very much like the biological feel to these series of sculptures and the way that trapped fibres are evocative of hair.

O’Connor, N. (2016) MMT Part 3 Molding & casting. Plaster, concrete alginate & modroc. PROJECT 2. At: (Accessed 6 February 2017)
Reynoldson, T. (n.d.) Balloon cast plaster sculpture project, part 1 of 4. [user generated content] Creat. Reynoldson, T. At: (Accessed 22 February 2017)
Reynoldson, T. (n.d.) Balloon cast plaster sculpture project, part 2 of 4. [user generated content] Creat. Reynoldson, T. At: (Accessed 22 February 2017)
Reynoldson, T. (n.d.) Balloon cast plaster sculpture project, part 3 of 4. [user generated content] Creat. Reynoldson, T. At: (Accessed 22 February 2017)
Reynoldson, T. (n.d.) Balloon cast plaster sculpture project, part 4 of 4. [user generated content] Creat. Reynoldson, T. At: (Accessed 22 February 2017)
Tucker, E. (n.d.) Erin Tucker, Plaster. At: (Accessed 22 February 2017)