Monday, September 19, 2011

Getting rid of the scum

“Soap consists of the sodium salts of fatty acids derived from naturally occurring fats & oils. These react with calcium ions present in hard water to precipitate out. This solid, combined with the emulsified dirt, forms the familiar ‘scum’.

Gels are synthetic detergents made from the sodium salts of sulfates or benzene sulfonates, which in turn are derived from petroleum products. They have the advantage that their calcium salts are soluble, & thus do not lead to scum production.

I am sure it would be possible to synthesise a sulfonate product that has the consistency of soap but without the scum-forming properties …
But would manufacturers want to market such a product, given the attractiveness (to them) of their gels & shampoos that so quickly end up down the shower drain?”
That elegantly succinct explanation was delivered in a letter to the editor of The Times from Professor Alan Swanwick of Dronsfield, Derbyshire in response to a moan about shower gels by Matthew Parris in his column of 8 September.

And it brought back so many memories for one who is old enough to remember the days before 1954 when synthetic detergents did not figure in our world.

That was also a world where, if you were lucky enough to live in the right part of the country, soft water came out of the household taps. Soap made suds, calcium salts did not precipitate out & the emulsified dirt & flakes of skin did not combine with them to form repulsive quantities of scum but floated off down the drain with the foamy bubbles.

You did however need to use very hot water & elbow grease to make sure that all the non-metaphorical grease was removed from the washing up. And hair was rarely truly gleaming because soap-based shampoos, combined with water that was a lot cooler than that used for washing saucepans & dishes, failed to remove all the natural oils from the surface of the hair.

The difference was really borne in on us when we left the soft north for a holiday in London in the 1950s, staying in Earls Court, where just washing your hands or cleaning your teeth were upsetting because of the scum. What made matters even worse was that both little sister & I caught nits, & so had to endure all the washing & tooth combing necessary for their eradication.

Hair washing & dish washing were the first jobs for which detergents were welcomed into our house – soap powder, in the guise of Persil, was still firmly superior for clothes washing, judged by the whiteness & softness of the result, in the opinion of decent housewives such as my grandmother.

Varieties of jewel-coloured, perfumed shampoo came from Woolworths in small plastic sachets, less than 2” square, from which you had to snip off the corner. In theory each sachet contained enough for one washing, but if you were economical you could make it last for two, as long as the sachet was stored carefully upright. That is four applications of shampoo, one to wash the scalp, then rinse & reapply shampoo this time concentrating on the hair. At first that meant using some your pocket money for this luxury only once a fortnight, since hair washing night (like bath night) came round only once a week. If you did not want to use your pocket money you could revert to the old fashioned soap based family shampoo provided by the housekeeping, which smelled terrible. No contest for a teenage girl.

You could also, if you wished, emulate a film star & have bubble baths, but most of us preferred, except of course for very special dances & dates, to rely on more economical old fashioned bath salts - a staple for birthday & Christmas presents - which provided merely perfumed water.

Later, life as a London student, & shared bathrooms meant that the pleasure of a relaxing bath was marred by the need to clean the bath properly – with scouring powder – when you were done, to remove the disgusting grey tide mark. And I learned that the melanin in dark skins was present even in the surface layer, which has the effect of making the tide mark the shade of pale cocoa, rather than the grey of 'white' skin.

Black skins are particularly prone to drying out in cold northern climes, which meant that skin was more easily shedded in the bath & even men had to use moisturisers (usually Johnson’s baby products). One of those facts of life which, I was both saddened & touched to hear years later, in a programme on Channel 4, was yet another cause of not always friendly ribbing in the dressing room for pioneering black footballers in the 1970s.

Almost fifty years later & the affluent bathroom is well supplied with sulfonate products which largely do away with these problems.

Which is just as well really, since it is a rare public water supply which, in this country, provides water soft enough to obviate scum.

Soft water, once such a source of pride – & which gave us the cotton industry - is now seen as a problem for human health &, in its extreme form as acid rain, a threat to the very planet.

There was a respectable theory that soft water was implicated in heart disease, particularly among men; natural soft water is most likely to be found in those areas which take their supply from upland rainwater sources – especially the gritstone & granite moorlands & hills of Wales, northern England & Scotland – as opposed to the underground aquifers of the chalkier south.

Despite the fact that drinking even mildly acidic liquids from vessels made of lead could cause poisoning was known from Roman times - & is attributed by some as the cause of the Fall of the Roman Empire – lead was commonly used to provide the pipework for the modern water supplies which, otherwise, did so much to improve the health & longevity of the population. In Glasgow, where there was particular pride in the soft pure water of Loch Katrine & the renowned quality of their engineering, citizens were proud of their real Rolls-Royce of a system which carried water from the Loch along a lead-lined aqueduct, to be stored in lead tanks in the roof from which it could be fed by gravity to the tenement flats below.

It was believed that concentrations of lead dissolved in the water would be extremely unlikely ever to rise to the level which could cause frank poisoning, & that any risk could be avoided by advising consumers in soft water areas always to run some of the water off whenever, for example first thing in the morning, it had been standing in the pipes for any length of time.

Water providers were under a statutory obligation to ensure that they supplied water which was safe for human consumption. From around 1950, as alternatives to lead for piping became more widely & easily available, the use of lead pipes for domestic plumbing was banned, though there was no concerted attempt to enforce the removal of lead pipes from all existing homes.

By the 1970s however concerns about environmental lead poisoning were rising – not least because of the increased emissions of lead from petrol - & European & WHO standards for the maximum permissible concentrations of lead in drinking water were being tightened; worry now focused particularly on the effect that levels of lead previously considered ‘low’ could have on children.

The near universal use of of sulfanate products for all household & personal washing helped to make it acceptable for all domestic water supplies to be treated with enough calcium or other ions to reduce the acidity of water & minimse its ability to dissolve lead from the plumbing system, without provoking widespread protest about scum.

Now in place of scum we can worry about limescale instead. Not to worry, there are manufacturers ready willing & able to provide you with a product to deal with that too. Result all round.

Personally I prefer to rely on lemon or lime juice.



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