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Mike Bullivant's diary: Paper and ink

Updated Friday 21st July 2006

Mike Bullivant's Mapping it Out diary, from the BBC/OU series Rough Science 2

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Day 1

First thing on day one of filming we gather on the beach to record Kate giving out the challenges. Kathy and Mike are to map the northern part of the island. Ellen and I are to make paper and ink, so that their findings can be charted. At the end of day three, we're to produce a map using as many coloured inks as we can squeeze from Carriacou. I like this challenge.

The first task Ellen and I face is to find suitable plant material from which to make the paper. I'm relying completely on Ellen's expertise here. Sure, I've seen paper made before - back in the UK - from stinging nettles. But this is on camera which is different. Ellen chooses two possible sources of fibre - the silk cotton tree and the milk wood plant. The former is a weird-looking tree with a root system the like of which I've never seen before. The part of the tree we're after are the seeds. These are catkin like, and we need to collect a couple of bucketfuls and then separate the soft fibres from the stalks.

Because of its sturdy, chain-like molecular structure, cellulose plays a structural role in a plant, supporting its weight. For paper-making, we'll need to break down the long fibrous cellulose molecular structure into shorter chains. These shorter fibres will then more readily be able to form a mesh: what we need for a good paper. To do this, I'll need to produce an alkaline solution of some sort, in which to boil the cellulose fibres. I decide on potash, which is simply made from the ashes from our wood fires dissolved in hot water (boil for 30 minutes) and filtered. The resulting solution turns out to be a surprisingly clear pale yellow liquid with a pH of around 10-11.

This should be adequate to break down the cellulose structure but just to make sure, I prepare some 'fortified' potash by adding slaked lime to half of the potash. To make the lime, it's enough to place some seashells (almost all calcium carbonate) off the beach in the kiln and heat them for a few hours at high temperature. The calcium carbonate is converted into lime (or calcium oxide), which when added to water produces slated lime (or calcium hydroxide).

When you mix slaked lime and potash (from the wood ashes, which contains potassium carbonate), you get a reaction that produces potassium hydroxide and calcium carbonate - a neat chemical dance, in which partners are swapped. Because the calcium carbonate is not very soluble in water, it falls out of solution and gives the liquid mixture a cloudy appearance (thereby confirming the formation of potassium hydroxide). Potassium hydroxide is a much stronger alkali than the potassium carbonate of the potash, with a pH of around 12. We'll try four different combinations in our attempt to break down the cellulose fibres to give paper - the cotton silk with potash and fortified potash, and milk wood with potash and fortified potash. All we need to do is mix the fibres with the alkaline solution and boil the mixture in the kiln for a few hours.

While the four solutions are bubbling away, Ellen and I try to extract some coloured inks from the various plants that she's found on the island. One of the key ingredients is iron sulfate: this not only reacts with the tannins in certain plants like logwood but it also serves as a mordant - the chemical that fixes the pigment to the paper surface. Iron sulfate is easy enough to make - you just take a few iron nails and dissolve them in sulfuric acid from the car battery. The result is a green solution, from which white crystals of iron sulfate (FeSO4) fall out on cooling. I decide to re-crystallize the iron sulfate in order to purify it. Our afternoon is spent mixing various solutions of plant extract in an attempt to get as many colours as we can. Some of these extracts change colour when you add (battery) acid to them and the brightest of the lot we get from the milk wood plant extract mixed with sulfuric acid - a beautiful red. Isn't Nature wonderful?! We've something like ten different coloured inks, most of them fairly dull, it has to be said. But then, that just shows how dull life must have been before the advent of synthetic dyes.


Day 2

Ellen's having problems separating out the short fibres obtained from our alkaline broth. I get the impression that she thinks we're not going to be able to get a paper that's sufficiently good to draw Mike and Kathy's map. I suggest that we should separate out the fibres by hand from the broth. As if by magic, the whole production crew rolls up its sleeves and two hours later, we've a flocculent mass of (short) cellulose fibres that'll do the trick. Problem is, the fibres are darker than we'd like and my attempt to decolourise them by boiling with animal charcoal (hooves in the kiln!) seem to have no effect. We'll have to run with what we've got - a glutinous mass of light-brown fibres. By the end of day two, we need to have the fibres in the press, so that we can squeeze all the water out overnight. I'm confident that once dried the paper we end up producing will be fine. We leave the lime factory at the end of day two with the prospect of an easy third day ahead of us. We've broken the back of the challenge. Tomorrow, Ellen and I can coast a bit.

Day 3

Sure enough, the next morning, when we release the paper from the press, my optimism is rewarded. The fibres, now virtually colourless, have formed a mesh that'll be fine. In fact, our paper looks quite good - nicely rough. All we need to do is dry it off in the sun. If we had longer, maybe the sun would bleach the paper and make it lighter but it doesn't matter; this'll be good enough as it is.

By the time we come to hand the paper over to Mike and Kathy, it's dried completely. Ellen and I have laid it out on a table and decorated it with the ten or so different coloured inks that we've made - each one in a different small shell off the beach. Our display looks quite beautiful - topped off, as it is, with arrangements of flowers and miscellaneous items we've found on the beach - as if to compensate for what is, after all, a largely drab selection of inks. It's up to Kathy and Mike to draw the map but Mikey chooses not to be too closely involved.

Two hours later and the map's drawn. Kathy and Mike's measurements and trigonometry have produced a fairly accurate map of the north part of the island. They've done well. As for our part of the challenge? Well, I don't know how Ellen feels but I'm really pleased - our paper has worked, as have our natural inks. It would've been nice if Kathy had had a few more hours to colour the map in, but despite this, it still looks good. If only we'd had a little more time...

We leave the lime factory at the end of day three satisfied but very tired. The heat and humidity are getting to me. I usually enjoy hot weather and I've never found it a problem but combined with the tension of filming, I find it enervating. I'm looking forward to that first cold beer in the bar when we get back to the hotel and the two rest days ahead of us before we embark on the next programme. Being out here seems strangely dream-like. There's a really bizarre air of unreality about the whole thing. I wish I could enjoy it more but something - whether it's the tiredness, the heat and humidity or the fact that I've been surrounded by people for the last two weeks (an unusual experience for someone like me who values their own space for much of the time) - something's getting in the way. I think I'll go to bed early tonight. Maybe I'll feel better in the morning.





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