Sponge Slab Building
Paper-clay goes synthetic and meets slab-building…
Having seen every third ceramics student buy expensive natural sea-sponges and dip them in slip to make exquisitely delicate and ultimately pointless decorative fronds, it occurred to me that synthetic car sponges might provide an interesting alternative and even offer greater potential:
Beside the sink in the studio I have a box of ageing and tattered synthetic sponges which take the daily abuse of cleaning grogged clay from worktop, hands, and tools. Purchased over the years from numerous sources, they each have their own colour, texture, spread of bubbles, density of cell-structure, elasticity and, well, character. Having also worked with closed cell upholstery foam before, I knew that it cuts cleanly using a fine-toothed band-saw, and so an idea began to form.
By taking the torn scraps of sponge, and slicing them thinly (about 5mm thick) on the band-saw, I produced a series of thin, irregularly shaped polygon slabs of foam. I then set about soaking each section in casting slip (any super-saturated body slip would suffice here).
In order to store these slabs in a humid, ‘leather-hard’ state, I poured an inch of plaster into the base of several large Tupperware boxes. Once the plaster had cured, I poured water into the boxes, soaking each plaster slab and creating, once the lids were clipped on, small damp-boxes..
So now, with dozens of small clay slabs kept in a nice, workable state, I could begin to build. I soon discovered that keeping a small pot of the same body slip on hand made sense for joining the seams, and also that the slabs could be easily cut to shape and size using everyday household scissors(!) The slabs were easy to flex, and held their shape firmly, and before long I was alternating the type of foam with each shape of the jigsaw, showing off the variety of textures available. – I noticed that the casting slip had a tendency to drain slightly through the foam slices and sit more thickly on the plaster slabs. In some cases the slip had pooled completely, encasing and covering the foam structure entirely. In other cases there was less difference between the top and bottom of the slab. Variety, however, there was, and I was determined that each facet of the growing vases would say something new.
The thixotropic, high clay content of the slip allowed for sections to be joined at an almost bone-dry state to each other and, in this respect it reminded me of working with paper-clay.
As with so many other experiments, I tried to let the process guide the look of the piece: Wherever possible I would prefer not to cut the sections, but rather select and insert a slab allowing it to change the direction of the surface organically.
Once biscuit fired, the texture revealed visual parallels with bone, and commercial breeze-blocks from the building trade. The patchwork quality also earnt it the affectionate nickname of Franken-sponge, or Franken-pot.
At this point I took the rare decision to try to reassert the original material’s aesthetic by trying to match the colour of the glaze to the colour of the original sponge fragments. I briefly contemplated staining the casting slip, but concluded that this would have resulted in a completely uniform, homogenous colour. Instead I plumped for carefully mixing Amaco velvet underglaze stains and painting each facet in various tones of synthetic sponge yellow.
The transparent glaze I chose fired a little too glossy to convey a convincing illusion, so I resorted to lightly sand-blasting the surface.
The whole process has a freedom and ease to it which I really enjoy. – One in the bank for the right project.
