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Rough Science 3 New Zealand: Mike Bullivant's Diary: Shakers

Updated Tuesday, 27th February 2007

Mike Bullivant attempts to manufacture hand cream halfway up a mountain. Because you're worth it.

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Mike Bullivant making hand cream Copyrighted  image Icon Copyright: Production team

Day 10 - Hand cream
I’m making hand cream on the second challenge. Luckily, the fact that we’ve been given a suitcase full of sheep’s wool at the start of the programme is a major clue as to how we’re going to go about it.

I know that all sheep secrete a waxy grease from their skins, called lanolin. Not only does this waterproof their fleeces, but it also acts as a fungicide and bactericide, protecting the sheep’s skin from infection. The challenge boils down to separating the lanolin from the wool, and purifying it in some way.

 

The initial plan is to wash the fleece in cold water to remove as much of the dirt and grit as possible. I can’t imagine that the lanolin will be soluble in hot or cold water, as it’s a complex mixture of organic fats.

If it were soluble, sheep would have real trouble out here on the west coast of New Zealand, as it rains so much. We can then wash the wool in boiling water, to dissolve up as many of the hot-water-soluble impurities as possible.

Being a waxy solid (imagine something between butter and candle wax) the lanolin should melt in the hot water, and being immiscible with it, should separate out as an oil on the surface of the water – a bit like what you’d get if you added a pat of butter to a pan of boiling water.

After filtering any undissolved matter from the hot solution, we’ll cool it down, whereupon the lanolin should solidify out as a greasy, yellow wax. That’s the theory, but, as ever, Nature will probably have a different idea.

True enough, by the end of Day 1, all we’re left with, after all the boiling and filtering, is a pot full of dirty water. There’s no lanolin floating on the surface, so maybe it is soluble in water.

Not too worried though, as we know that if there’s lanolin in the sheep’s wool we’ve been given, most of it will have been extracted and it’ll be in the water. What’s more, we still have two more days to go.

Day 11- Hand cream
Decide for the first half of this second day to repeat what we did yesterday, in an attempt to boost our yield of lanolin.

Everything goes to plan - sort of. As I start to reduce the solution down, the oily lanolin comes floating to the surface. The trouble is, there doesn’t seem to be very much of it, and, what’s more, it’s a dark-brown oil - not yellow, as I expected.

The dark colouration’s down to impurities in the lanolin, and I suspect that I can purify it easily enough by repeatedly washing our recovered oil with hot water - but why is there so little of it? I then realize that I can force more lanolin out of solution by adding lots of table salt (sodium chloride) to the pot.

This will make the water more ionic – something that organic fats and greases don’t like. Sure enough, when I add the salt, heat the mixture up, and cool it down again, much more of the dark-brown oil floats to the surface. Success!

By the end of Day 2, we still don’t seem to have extracted very much lanolin though. Then we realize that the wool that we’d been given looked suspiciously clean.

More often than not, when you see a sheep, its coat is really dirty isn’t it. We suspect this wool’s been cleaned up, in which case much of the lanolin had already been washed out of it before we got to work on it. Ho hum!

Still, we have enough of the impure, brown, oily stuff to work with tomorrow, and Kate H didn’t actually specify how much hand cream she wanted. Just as well.

Tomorrow we have to purify the oil. It occurs to me that if I leave the pot containing the oil/water out in the cold overnight, the lanolin might just freeze out of the oil as a solid. The temperature here drops to minus 5 Celsius overnight, so it’s worth a try. I leave the sawmill feeling more than happy with the way the second day’s gone.

Day 12 - Hand cream
Well, the lanolin didn’t freeze out overnight, even though we had a very heavy frost. So we have to try an alternative way of purifying our dark-brown oil containing the lanolin.

Then I have a brainwave. I’ll try a little trick that we chemists often use to purify organic chemicals – a process called solvent extraction. There’s some olive oil in our storeroom in the sawmill. As we all know, olive oil and water don’t mix.

If I take some of the impure lanolin oil, shake it up in a bottle with some clean brine (water containing table salt) together with a smaller amount of the olive oil, the lanolin, being a grease (a solid fat), will prefer to dissolve in the upper, olive oil layer rather than the lower, water layer.

I can’t believe what happens when I shake the bottle. All of the coloration in the impure lanolin oil is taken up by the water. More interestingly, an off-white ‘solid’ has formed as a separate, third layer between the olive oil and water layers.

Given the amount, this can only be pure (or at least, much purer) lanolin. The purification process couldn’t have been simpler. All that remains is to decant off the olive oil, and scoop off the lanolin. If our lanolin contains a little olive oil and water it won’t matter – it will be pure enough for our purposes.

To make the hand cream, we merely add the lanolin to some molten beeswax that we’ve been given. To perfume it, we stir in some tea-tree oil that I’ve extracted (using steam distillation) from some leaves Ellen collected for us. The cooled mixture is fragranced lanolin hand cream. Not bad, even if I do say so myself.

 

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