Was Olive Oil First Used as Fuel?

[Forester]

Ancient Cypriots fed olive oil to furnaces-study

PYRGOS, Cyprus (Reuters) - It is praised for its culinary and health properties by any cook worth his salt, but long before olive oil made it into the Mediterranean diet Cypriots used it as fuel to melt copper, archaeologists say.

Italian researchers have discovered that environmentally friendly olive oil was used in furnaces at a site in southern Cyprus up to 4,000 years ago, instead of the fume-belching charcoal used in industry for hundreds of years since.

Described as "liquid gold" by the ancient Greek poet Homer, olive oil has long been associated with grooming, pampering and the religious rites of the ancients, but not - at least in the Mediterranean - with heavy industry.

"We know that olive oil made it into our food around 1,000 BC, but it is the first time we have laboratory evidence that it was used in smelting as a fuel," archaeologist Maria Rosaria Belgiorno told Reuters.

Cyprus was famed in antiquity for its copper and is believed to have given its name to the Latin term for the metal, Cuprum....

[FreeThinker]

This is just a total guess but I imagine all the various basic properties of olive oil would have been more or less known gradually. The fruit when squeezed is oily...maybe a salve value, food value, fuel value would have more or less developed together.

If olive oil was being used to smelt copper it would have been in conjuncture with charcoal. Regular wood burns at too low a temperature no matter how dried. Wood is made mostly of cellulose and carbon. It is the cellulose that inhibits the temperature so the ancients would burn off all the cellulose with a slow burn/smolder technique. Even with the use of coal a similar principle is employed. Coal has a lot of carbon in in it but a blacksmith will burn off all the sulphur and other crap before he can get the coal up to heat. It is during this burn off that coal produces its worst emmisions. Once you get down to the raw carbon you can really crank the heat up. Raw carbon will burn away to ash more more slowly, but it will burn away. My guess is they were dousing the raw carbon coals with the olive oil to keep them from burning away to ash and giving some additional fuel for the fire reaction to consume. I would be interested to know the burning temperature of olive oil as compared to say oak or coal. Copper melts at close to 1100C (close to 2000F). It would need to be HOT.

I have been interested in trying to recreate some ancient copper smelting and casting (bronze too) useing all ancient techniques. The olive oil might be a nifty trick to keep the heat up. Anybody have the burning temps for olive oil?

[Forester]

If olive oil was being used to smelt copper it would have been in conjuncture with charcoal.

Perhaps, but the article states that:

Belgiorno said researchers were puzzled by the fact that no charcoal -- the fuel most widely used at the time -- was found. Charcoal remains intact despite the passage of time, she said.

"There were no storage areas for charcoal. We have discovered that to melt copper you need five kilos of olive oil, compared to 80 kilos of charcoal."

No charcoal found. Interesting, isn't it?

[FreeThinker]

LOL!!! See, that is what happens from not reading the article carefully like I should have. Heh! Hmmmm...and it is odd...how damn hot does olive oil burn and what was it using as a medium? It wont burn on its own (try lighting it with a lighter), so how was it employed here? No charcoal? That DOES pose a mystery. Unfortunately the article is very clear that no charcoal was used but entirely vague as to how the olive oil was burned. Any good ideas?

[Forester]

I see your point. As a guess, and it is purely that, I would say that to get a high enough temperature with a good oxygen mix, the oil would have to be sprayed in, like an atomizer, rather than poured in as a static liquid. Maybe forcefully blown through a tube into the fire, to create an aerosol? Somewhat hazardous to the "blower" to be sure, but what smelting process of the time wasn't?

Andy

edited to add, I would take the bet that said smelterers would be sans eyebrows, and perhaps have a "receding" hairline.

[Rokcet Scientist]

LOL!!! See, that is what happens from not reading the article carefully like I should have. Heh! Hmmmm...and it is odd...how damn hot does olive oil burn and what was it using as a medium? It wont burn on its own (try lighting it with a lighter), so how was it employed here? No charcoal? That DOES pose a mystery. Unfortunately the article is very clear that no charcoal was used but entirely vague as to how the olive oil was burned. Any good ideas?

Correct, FT: olive oil needs a "wick" to burn. A piece of straw or cloth will do. BUT... you'll only get a very small flame that you can use for light (very little to be sure, but still). However, you'll never get a raging fire capable of producing a smelting point of 1,100 degrees C!
Besides, the "wicks" would have left carbon traces...

Smelting ovens probably burned plain wood. And lots of it. The ovens – through their dynamics – would be capable of reaching the 1,100 degrees C smelting point.
It's highly unlikely they could reach that with olive oil.

[stan]

I would be interested to know the burning temperature of olive oil as compared to say oak or coal. Copper melts at close to 1100C (close to 2000F). It would need to be HOT.

Wood has been used for centuries to create ceramic stoneware, which
requires 2250 degrees farenheit.
You have to use a lot of wood burning very fast, as in a groundhog kiln, which draws a tremendous hot-air current over the clay.

[Rokcet Scientist]

I would be interested to know the burning temperature of olive oil as compared to say oak or coal. Copper melts at close to 1100C (close to 2000F). It would need to be HOT.

Wood has been used for centuries to create ceramic stoneware, which
requires 2250 degrees farenheit.
You have to use a lot of wood burning very fast, as in a groundhog kiln, which draws a tremendous hot-air current over the clay.

Exactly: wood furnaces. Not olive oil.

[Minimalist]

Well....if you had ever started a fire in a skillet while trying to saute chicken you'd know that olive oil burns.

[Guest]

Correct, FT: olive oil needs a "wick" to burn. A piece of straw or cloth will do. BUT... you'll only get a very small flame that you can use for light (very little to be sure, but still). However, you'll never get a raging fire capable of producing a smelting point of 1,100 degrees C!
Besides, the "wicks" would have left carbon traces...

Smelting ovens probably burned plain wood. And lots of it. The ovens – through their dynamics – would be capable of reaching the 1,100 degrees C smelting point.
It's highly unlikely they could reach that with olive oil.

And exactly how would a "wick" leave carbon traces, whereas "lots" of wood would not?

[Forester]

The guest post was me.

Wood has been used for centuries to create ceramic stoneware, which
requires 2250 degrees farenheit.
You have to use a lot of wood burning very fast, as in a groundhog kiln, which draws a tremendous hot-air current over the clay.

You guys are totally ignoring the data. No wood traces were found, only olive oil traces. You are saying "not possible" instead of looking for ways that it could be done. Charcoal is nothing more than partially burned wood, and leaves the same traces as burned wood. No such was found. So how do you account for this?

[Frank Harrist]

Some sort of porous, non carbon, substance like maybe pumice? It would hold the oil and lots of air too and acted as a wick. Just an idea.

[Rokcet Scientist]

Not bad, Frank. Let's see if we can expand on that.
So let's say that burns well. Now for the next step: how do you get that flickering fire to turn into that 'raging fire capable of producing a smelting point of 1,100 degrees C'?

[Forester]

Again, you guys are assuming that a simple fire is used in smelting. Actually, forced air in an enclosed space must be used to raise the temperature. You need a kiln, with holes in the base for tubes to blow air in. Early kilns used lung power, but bellows were used later.

Use olive oil-soaked ore to start with, place it in the kiln, and then "spray" olive oil in with the forced air in a form of a mist. Ever hear of a "fuel air explosion?" Very high temps can be achieved this way. With just lung power, take a sip of olive oil, blow into the kiln tube (called a "tuyere"), and repeat as needed. No wood required.

[Rokcet Scientist]

Sounds good, Andy. But I suspect that requires an almost incredible effort by those blowers. How long would they be able to keep that up – at 1,100 degrees C – and would that be enough for smelting copper?
Has this ever been replicated to see if it would work in real life?