Material Interventions

Substrates Update

After waiting for both test substrates to thoroughly dry I can report that the cellulose seems to have been quite successful, appearing smooth and free of cracks. However the surface is pretty fragile so I’ll need to be very careful when applying the pigment so it doesn’t flake away.

The silica and plaster mix has cracked in places unfortunately. However the uncracked areas have formed a solid, workable surface, so I want to persevere with these materials. Today I’ve remixed using different proportions of silica, plaster and water and again left them to dry. I’ve also applied pigment to the cellulose, and again am waiting for it to dry in order to gauge success.

Precipitates and Substrates

Precipitate: Noun

A substance precipitated from a solution.

Substrate: Noun

A substance or layer that underlies something, or on which some process occurs, in particular.

To be usable, all pigments need to be carried in some sort of solution. As the solution dries, the pigments (the precipitate) bind to whatever surface it is that they’re on (the substrate).The vibrancy and permanence of the colour will depend a great deal on the choice of materials selected both as binder and substrate.

I have been obtaining pigments from natural materials in a wonderful array of colours. My next challenge is to learn how to create perfect surface finishes worthy of artworks, and fix the pigments to create colours that will last.

If I was dyeing a cloth I would use a bath of alum to fix the pigment to the cloth, but the process becomes more tricky when dealing with pigment applied to a solid, flat surface.

Last week I visited my sister in London for a few days. She is a paper conservator and has a great interest in, and knowledge of, natural pigments. Historically, pigments of this sort were used in inks to colour documents and artworks, and so must now be recreated by conservators in order to repair these old works and gain an understanding of how best to preserve them for the future.

Fiona has done many tests using natural dyes on paper and explained to me the need for binding mediums to make the pigment usable and hold the colour on the page. Pigments are fixed to a precipitate formed with alum and potash or to a chalk substrate.

However I have found in my own tests that when trying to use my pigments on other ‘artwork’ surfaces such as glass and board and with the addition of industrial solvents and resins, these chalky substrates tend to fracture and crack as they dry.

In an attempt to resolve this issue I’ve spent today experimenting with alternatives.

Initially I wondered about using something like traditional gesso or egg tempera as I figured both of these might be a little more flexible than the chalk and water slurry I have been using. However when discussing it with my chemist he came up with a couple of suggestions which may be better suited to mixing with the solvents and resins I am using. As I’m always keen to try something new, this sounded like a great plan, and so I got out my gloves, mask and digital scales and got down to business.

Option 1 is cellulose powder, which is very sticky when mixed with water, so no additional binder is needed. It’s also very absorbent so should be able to soak up the maximum amount of colour.

Option 2 is silica; this is similar to the stuff you sometimes find in tiny packets inside handbags and the boxes of new shoes. Its water absorbing properties are used to protect products by soaking up any moisture in the air, so it should be perfect for absorbing pigment solutions too. I also added a dash of plaster to the mix to increase its binding properties.

Both mixtures have been used to coat a selection of surfaces and I’m now waiting for them to dry. My chief desire is to eliminate the cracked texture that reoccurs throughout my earlier trials. Hopefully the drying process won’t take too long in this warm weather and I’ll be able to gauge my success in a day or two.

The Essence of Foams

I have noted in many of my resin experiments that when I add certain substances and pigments to resins, the cured resin contains thousands of minuscule bubbles; a kind of solidified foam. Although I’ve discovered that this is caused by oxygen and moisture, it’s still incredibly difficult to recreate deliberately. And when I do, although it looks awesome, the structure is unstable and breaks easily. Not good for making permanent art.

My quest for mastering the creation of bubbles was something I put to Pete the chemist upon his last visit to my studio. Apparently the reason that my foams are so breakable is because when the bubbles form they don’t stay separate from one another, but instead their walls conjoin to form ‘super bubbles’ made up of a multitude of tiny ones. Think of the crossover part in the centre of a figure of eight splitting so the two loops become one giant misshapen hole. Without a regular structure, and with walls too weak to support their length, these bubbles cave in upon themselves as soon as they are subjected to any force. So what’s the solution?

Well it seems that the only thing to do is design polymers with the specific goal of creating a structurally sound foam. This is where a polymer chemist comes in, designing a resin which deliberately foams as it sets to create millions of tiny, evenly sized bubbles which remain intact and whole, and do not join with their neighbours.

Pete introduced me to the exciting world of polyurethane foams during his recent visit to my studio. A small quantity of resin was mixed with its catalyst and poured into a pint glass… And then it foamed! It foamed so much that it almost escaped from the glass! Once set and I had sliced it through, the perfect structure of bubbles was revealed. It’s put me in awe of polymer chemists, because however does someone go about designing a material that always reacts in such a specific way?

I’m not yet entirely sure what I’ll do with this piece of research but I’m fascinated by it nonetheless.