Material Interventions

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.

Pigments and Solutions

I pledged to share my research as part of my current Arts Council project; the only thing I’m finding is that now I’m well and truly immersed in exploration, it’s become difficult to know what exactly is useful and worthwhile to share!

The freedom to experiment has encouraged me to dabble with materials and processes all over the place, but I seem to keep returning to recurring themes. Yet again I find myself attempting to extract the ‘essence’ of various things; all of them objects with a capacity for being imbued with any amount of personal significance. This week the objects have been flowers. I’ve always been interested in capturing the soul of things. My Fabric of Life project was a series of portraits of people from my local community, painted upon fabric which they had donated.

This could have been an old item of clothing imbued with deep emotional significance and memory, or furnishing fabric remaining after the redecoration of a home. Clothes, furnishings, fabrics and patterns provide unique clues to the identity and personality of their owner. By using fabrics with a past life within my painted portraits I desire to capture a depth of substance and facets of character which paint alone cannot describe.

In addition, clothes and furnishings are transient by nature, but once captured and preserved within an artwork they attain a new level of permanence. I think this is what has also interested me about flowers; they often mean so very much (think of wedding bouquets and the Victorian’s language of flowers LINK), and yet their existence is so incredibly fleeting. But what if I could extract the essence from a flower and preserve it forever?

For me as a visual artist, an object’s essence is definitely made up of its pigment or colour. Surely if each species of plant and flower is unique, this must mean they contain their own personal series of pigments within their leaves and flowers? In this way, I suppose the colours extracted from a particular plant species to be some kind of unique fingerprint in a combination specific only to that one species.

So how to find out? I remember extracting chlorophyll from leaves in high school chemistry lessons; mushing leaves up in a beaker filled with solvent or alcohol. This seemed as good a place as any to begin.

I mashed up leaves and blooms in acetone first, then repeated the process using surgical spirit and alcohol (vodka). Varying quantities and concentrations of pigments were obtained as a result. However the colours were pretty disappointing, being neither strong nor bright. I decided that more research was needed.

Websites on natural dyes and dying were my next useful source of information, advising to boil the plant material in water for an hour and then let stand overnight at room temperature to extract the maximum amount of pigment. I tried this but once again wasn’t impressed by the results. Further improvements were still required, and so I contacted my collaborative chemist for assistance.

Apparently there are three main methods of successfully extracting pigments from plants: the acidic method, the alkaline method and the alcoholic method. Of these I intend to try only the second two, as the acidic method involves boiling hydrochloric acid; something I don’t think is very advisable to try at home! The alcoholic method can be easily done by boiling the plants in a solution of alcohol (I intend to use surgical spirit). The alkaline method is similar, boiling the plants in a solution of sodium carbonate. The chemist has assured me this is a fairly benign process as long as I have adequate ventilation. A variation of the alkaline method can also be done using a solution of sodium hydroxide… this is otherwise known as caustic soda- I won’t be boiling that in a hurry!

Watch this space for the results… I’m off to the hardware store now for my supplies.

Childish Experiments #2

In my quest for a solvent which can remove newsprint ink from newspaper I’ve been doing a bit of online research. Whilst doing this I’ve rediscovered an activity I remember from my childhood. It wasn’t so much an experiment, more an interesting discovery, that Silly Putty (the fascinating, mouldable, semi-solid goo in a plastic egg) will pick up the text from newspaper when they are both pressed together.

So as a child I would go around collecting text and images from newspapers on my flattened Silly Putty, then squishing the putty together until the writing had gone. I’d repeat the process over and over until the olive green putty turned black from all the blended ink. I don’t remember ever wondering why the transfer of text was so successful with the putty, and yet didn’t occur when using other mouldable substances such as clay. It turns out there is a scientific reason for this. It’s all to do with the solubility of the ink.

A rule of thumb for solubility of two substances is “like dissolves like.” Polar substances (such as water or alcohol) will dissolve other polar substances. Likewise, nonpolar substances (such as oil and fat) will dissolve other nonpolar substances. However, polar and nonpolar substances (oil and water) do not dissolve in each other. Newsprint ink is a pigment suspended in oil (a nonpolar substance) which is adsorbed by the paper. Since Silly Putty picks up the ink from the newsprint, it must also be a nonpolar material. The pigment-oil suspension of the newsprint ink is readily adsorbed by Silly Putty. Our oily skin often picks up newsprint for the same reason.

From this, I can conclude that inks which the Silly Putty cannot pick up are polar substances and therefore are not readily picked up by the nonpolar Silly Putty.

So does this then give me a clue as to how to dissolve newsprint? Nonpolar solvents, as a rule, sound pretty unpleasant to me…

At least this discovery has started me thinking about testing a greater range of solvents to discover which may share the polarity with the various inks and pigments I have been using. So far I’ve tried numerous household cleaning solutions, as well as acetone, surgical spirit and white spirit, with varying success. My next batch of experimentation will be with various inorganic salt solutions; beginning with table and Epsom salts, and then progressing away from the commonplace and further into the world of chemistry. I’m curious to see how they may react when placed side by side with a selection of pigments, inks and solvents… *dons mask and gloves*

Childish Experiments

With a research and development project it’s sometimes hard to know where to start, for with so many possible avenues to explore, the possibilities are endless.

A recently rediscovered book from my childhood has been supplying me with my current inspiration. It was written in the 1980s, an era in which, I guess, we as children must have been much more innocent and easily pleased than the children of today. Activities include such gems as how to make a mouse and twirling ballerina out of a pocket handkerchief. My attention was caught however, by a recipe to make an image transfer medium using white spirit and soap.

While I can’t say that the images I transferred using this method were entirely successful, they have led me to an interesting line of enquiry around the capturing of images for insertion into resins.

I’m particularly keen on the idea of physically ‘capturing’ the ink from a page as opposed to reprinting or copying the page as I love the idea that the removal of the ink and its encapsulation is extracting and preserving the soul or essence of the book/newspaper/printed words; somehow more pleasing to me than simple reproduction. My next step will be to experiment with solvents/alcohols to see whether I can dissolve the ink from the page. Any suggestions as to what may work would be gratefully received!