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18 Jul 2016

Twenty-five years ago Iraqi forces opened oil valves to impede the troops trying to liberate Kuwait.

What unfolded was easily the biggest oil spill in human history, with 4000 square kilometres of Kuwait covered in a 10 centimetre thick oil slick.

Four million barrels, or 480,000 m³, of oil spilled out onto the land and sea.

It was almost enough oil to fill Sydney Harbour.

About 50 per cent of the volume evaporated, 25 per cent was recovered and the rest is still sitting there, including a lot of oil that enters waterways and washes up on Saudi beaches.

Quite a mess to clean up.

Reminded of this, I recently helped a colleague to clean up a much smaller oil spill in the rear foot-well of his Honda Civic.

Seems that he’d bought 5 litres to do an oil change which he then completed.

The remaining 1.5 litres in the container didn’t find a place on the shelf in his workshop, but rather was put back behind the driver’s seat.

Sometime in the next two weeks the container slipped side-ways and, can you believe it, the top wasn’t sealed.

Discovering that there was one litre still left in the container, we estimated that the total spill was only 500 milllilitres.

But how do you pick up two cupfuls of oil and put it back where it came from?

The internet was the obvious place to seek advice.

Absorbent paper towels did a good job in step one, but the carpet still seemed sodden with oil and felt greasy no matter how many paper towels we used.

Step two would necessarily involve a chemical attack, but that would have to be after the laborious job of removing the carpet from the vehicle.

Most automotive carpets have a perforated backing so that dampness can dry out.

Those perforations are just as able to allow fluid to get under the carpet as well.

Half a day was all it took to get the carpet out after the seats, door sills and centre console were removed.

Cleaning the shiny metal floor-pan was easy with just a rag and any old detergent.

Cleaning the oil from the carpet was going to be a lot harder.

According to the internet, the best place to start was with bicarb of soda or sodium bicarbonate (NaHCO₃).

Sprinkle it on, let the crystals soak up the oil and then vacuum them up.

Sorry, but that didn’t cut the mustard - though sodium bicarbonate is still a pretty good antacid.

Next thing was dry cleaning fluid or tetrachloroethylene (Cl₂C=CCl₂).

A chemical solvent should dissolve the oil, but with the carpet fibres having such a big surface area, there seemed to be no way of shifting the oil without flooding the carpet, which might also be dissolved by the cleaner.

Next we tried degreasing oil.

On paper this approach did look promising with a greater volume of solvent.

In practise, the carpet was just as greasy after de-greasing and, to make matters worse, it now smelt like degreaser.

Our final line of attack was with good old-fashioned amphiphilic detergent.

The hydrophobic “fat-loving” end of the detergent molecule would dissolve the oil, which should then just wash away with water.

As the spill had been in a car, we started with car wash detergent.

Somehow, it just didn’t seem to cut the grease, so we tried dishwashing detergent, which similarly failed to impress.

While the process was gentle on our skin, the carpet still felt oily.

With the options reducing and the distinct possibility of admitting defeat and ordering a new carpet on eBay for US$200, we gave it one last try.

Laundry detergent was never meant to be tested on humans or animals, but it was good for cleaning overalls.

With more surfactants, enzymes and optical brighteners this had to work, and it did.

That corner of the carpet was now so clean it left the remainder looking decidedly dirty.

So there was no other choice but to push on and remove the chocolate, mud and two litres of dehydrated Coca-Cola that was deposited elsewhere on the flooring.

Next job, Kuwait.

Safe motoring,
Clive Fraser


Published: 18 Jul 2016