Novelist's problem - preserving ice in ancient times

[Ketman]

In those days ice was transported from mountain regions to towns and cities, so that, for example, wealthy families could have interesting desserts at their banquets. And I imagine some market-sellers might have used it to keep their produce fresh - displaying sea-food in an ice-tray, for example. Internet sources are a bit vague on the technology, but an obvious problem is how to transport the ice without too much of it melting. All I can do is make reasonable guesses.

As a form of heat-insulation, there was probably nothing better than wool. I'm thinking raw wool packed in hemp sacks. But, of course, if that was all you used, it wouldn't last long. As soon as the ice melted at all, it would melt fast, because it would soak the wool, which would cause it to cease being a good insulator. So you'd need an inner layer of water-proofing. In those days it could only be animal hides, though I suppose metal drums is a possibility. I'd incline towards the former, because transport from mountain regions, at least in the initial stages, couldn't involve wheeled vehicles. It would have to be carried by mules or donkeys, and weight would be a big consideration. I don't know how porous leather is in its natural state, but treated with some kind of oil, or coated with tar, it might be quite effective.

What I can't even guess at is how long the ice could be expected to last, supposing that the buyers stored it under the same conditions, and preferably in a cool cellar. Is it feasible to expect that, say, half of it would still be frozen after a week?

All thoughts on all aspects are welcome.

 

[SteamKing]

Materials like wool or leather are too valuable and expensive to be used as insulation. For the ice houses in antiquity, straw or sawdust was used to provide the insulation for ice in transport and storage. Ugh, I can't imagine anything worse than a mass of sodden wool.

http://en.wikipedia.org/wiki/Ice_house_(building)

 

[Ketman]

No, a mass of sodden wool wouldn't be good. But probably no worse than a mass of sodden straw. That's why a waterproof inner layer would be desirable. Still, thanks for the link, which I hadn't seen before. What I had in mind was the transportation of smaller amounts than would be stored in an ice-house like the ones described. The Persian ice-houses of antiquity had more sophisticated methods of insulation than those, which would be economical for the huge amounts they were designed to store. But the amounts I'm thinking of would be no more than could be stored in a medium sized boat crewed by five or six men. Provided you did make the inner lining waterproof, it's then a matter of choosing the outer insulation. Although straw is a good insulator, I think wool would be better. I don't know why you think it would be expensive. It would be raw, unprocessed wool, stuff swept up from the floor of the shearing shed. Used repeatedly, it would pay for itself soon enough.

 

[SteamKing]

We are so used to abundance of everything nowadays, it is easy to forget that not long ago, some products commanded much higher relative prices than they do currently.

Wool is one of those commodities which is taken for granted today. Prices for wool dropped quickly once synthetic fibres became available using mass-production techniques. Nylon, rayon, etc. can be made year-round, 24 hours a day, if need be.

http://en.wikipedia.org/wiki/Wool

At one time, smuggling wool out of England could get your hand chopped off. Unlike straw, you've got to provide pasture for your little wool-makers; straw can come from anywhere. And, you can't just shear your sheep anytime you want; the little buggers would freeze in the wintertime without their woolies.

Some fine wool can still command astounding prices: the most recent record was approx. $3000/kg for some especially fine Australian wool.

But, I can see you want to spin a yarn, as it were.

 

[Borek]

I am sure straw was used even not that log ago, somewhere before WWII. There was a huge ice selling company not far from the place I was born - while it was many years before my times, it was part of a local history that I learned quite recently. They collected ice in winter building huge stacks of blocks cut from the neighboring pond, and isolated them with straw covered with earth.

 

[Ketman]

We are so used to abundance of everything nowadays, it is easy to forget that not long ago, some products commanded much higher relative prices than they do currently. Wool is one of those commodities which is taken for granted today...

Perhaps you are not aware of how essential sheep were to the economies of the ancient world, and how numerous they were.

If it hadn't been for wool, the Romans would have frozen to death. In ancient times, at least in the west, not only was wool the most common material for making clothes, it was for quite a while just about the only material. Cotton wasn't available at all until late on in the Republic, when it had to be imported from the east (obviously). It was a luxury. Even linen was a later development in Roman times, and that too was imported. Wool was the only homegrown clothing material they had.

My parents retired to a farm in Leitrim, Ireland, in the 1960s and had a modest flock of about 200 sheep. They were shorn in the spring, for their own health rather than for the small amount the wool would have fetched, and you could scrape up at least three sacks from what was discarded on the floor. For modest sea-traders during the period of the later Republic, getting enough raw wool to insulate a cargo of ice would not have made too much of dent in their finances.

However, whether it is a better insulator than straw is not something I'd care to pronounce on, so if anyone knows, please shout.

 

[D H]

Why guess when you can look it up? There's lots on the internet on the history of how ice was stored.

 

[etudiant]

There is still a substantial ice house at the Hancock Shaker Village in NY State.
The very detailed documentation indicated that the ice blocks were cut from lakes in winter and then insulated with sawdust. The ice lasted through the summer. There was a thriving business shipping New England ice to the South, including even the West Indies.
Ice mixed with wood shavings is remarkably slow to melt. In fact, during WW2, there was an effort to build a floating iceberg aircraft carrier from this material, dubbed Pyecrete after the inventor. The effort was abandoned because aircraft range improved enough to cover the entire Atlantic, but the idea was deemed practical.
In earlier days, the Romans brought snow to cool the Imperial wine in straw insulated carriers, but the quantities were comparatively minute.

 

[Ketman]

There is still a substantial ice house at the Hancock Shaker Village in NY State.
The very detailed documentation indicated that the ice blocks were cut from lakes in winter and then insulated with sawdust. The ice lasted through the summer.

That's interesting to know. I didn't imagine it would last that long. I've found a couple of links to it, so I'll give those a read. Thanks.

 

[Hornbein]

Wet wool will still keep you somewhat warm. Skiers know this.

 

[AlephZero]

At one time, smuggling wool out of England could get your hand chopped off.

And stealing a sheep would get you hung. Wool was big business. Many of the churches in Eastern England were "buiit on wool" - i.e. from the profits from the land they owned. This one is typical (with sheep still being used to mow the grass in the churchyard) - when it was built the village population would have probably been only a couple of hundred people, and a lot more than 200 sheep.

There wouldn't have been "sacks full" of wool left on the shearing floor in those days - it was worth too much!

 

[UltrafastPED]

If it hadn't been for wool, the Romans would have frozen to death. In ancient times, at least in the west, not only was wool the most common material for making clothes, it was for quite a while just about the only material. Cotton wasn't available at all until late on in the Republic, when it had to be imported from the east (obviously). It was a luxury. Even linen was a later development in Roman times, and that too was imported. Wool was the only homegrown clothing material they had.

Linen was used long before Roman times: http://en.wikipedia.org/wiki/Linen#Antiquity
and: http://www.die-leinenweber.de/linen-cultural-history-en_10.html
and: http://www.timeless-creations.ca/Linen.pdf

Wool first shows up about 3300 BC; prior to that sheep had hair like goats - the curly wool was a mutation. One advantage of wool is that it takes dies much better than linen does.

 

[SteamKing]

I think you mean 'dyes'.

The classic Roman toga was a woolen garment. The undergarments were made of linen.

 

[AlephZero]

As another historical digression on the historical importance of wool to the English economy:
http://en.wikipedia.org/wiki/Woolsack

 

[Chronos]

Sawdust was the most popular insulation for ice houses. It was a nuisance waste product of lumber mills, which were plentiful, and had few competing applications. Straw, by comparison, was relatively expensive and in demand. In coastal regions seaweed was also a popular and effective insulating material.

 

[rollingstein]

Sawdust and straw yes.

Wool as ice insulation I've never ever heard before. Sounds a bit bizarre.

In the developing world as late as 2000 I've seen ice blocks being hauled by mule / horse carts and the vendors seem to have used sawdust with hemp / jute sack cloth on top.