Monthly Archives: December 2013

Thatched Roof

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So I’m writing away (or trying to) in my alternative version of 11th century Ireland., when my characters had to thatch a shelter. Yikes, so how does one thatch a roof?

Screen shot 2013-12-24 at 5.06.01 PM

Note the straw/reeds are cut side down. Ahh…the aluminum ladder may be a bit difficult to find in 11th century Ireland…

Material:
A common reed (phragmites communes) is one typical plant used for thatching. Also wheat straw is used but care must be taken not to damage the straw during threshing (removing the grain from the stalk).
See: http://www.reed-thatching.com/thatch-types.htm

Modern construction:
Was surprised to find that the bottom (thicker) end of the reed is placed “downhill”.
See: http://www.youtube.com/watch?v=qtcaWfsLR0k
See: http://goo.gl/BpcNNS

And when you get done, you can trim the roof:
See: http://goo.gl/GCx4mB

Brain Tanning

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Ain’t got enough brains to tan his own hide.

Ever hear that saying? Well, it is becoming a little dated. Not too many people tan hides now-a-days.

But prior to the industrial age, clothing was not cheap. If one had access to fibers, plant or animal, one could spend days/weeks manually spinning enough yarn from which to weave a piece of cloth. Only then could one actually make clothing.

So for many, the only real options were animal skins (or running around naked).

Even so, turning animal skins into wearable leather (with or without the hair) was an arduous process, taking several days. (But still quicker than spinning and weaving).

The rough steps:

1. Kill something (hopefully with enough brains to tan its own hide…which, in the animal kingdom, is true…not sure about some humans).

2. Scrape the hide of fat and remaining meat on the inside. For the outer part of the hie, one has to make a decision: keep or remove the hair. For a sleeping hide or winter cloak, it would be best to keep the hair on. This does make the process more difficult.

Scraping can be done with sharp-edged stones, antlers, bone, or metal (if available). Two methods of supporting the hide: stake out on the ground. Or tying up on a frame (if wood was available).

Frame for tanning hides

Stretching frame for tanning hides

Removal of hair could be made easier if soaked in mildly acidic (urine) or alkaline (wood ash) solutions. In any case, it would be a lot of work and one had to be careful not to cut the hide.

3. Brain treatment. The brains are boiled and then mashed up and vigorously rubbed into the hide (both sides if hair removed, otherwise only the non-hair side).

4. Stretching. This softens the hide. This actually starts while the hide is stretched on the frame (less so is staked on the ground). The pressure while scraping starts this process.

Even while on the stretcher (after de-hairing and brain rubbing), one can use a thick blunt (and smooth!) stick to push against the hide. This does some stretching and for the hide with hair still attached, this may be sufficient.

For a soft hide, one can repeatedly pull the brain-soaked hide back and forth over a smooth, de-barked tree branch or log, turning the hide to stretch all parts.

5. Smoking. To keep the hike soft even when wet, one can smoke (not cook!) the hike. One common method is to tie the hide into a cone or tube and suspend over wood-chip covered embers. One would have to reverse the hide to smoke both sides. The smokey residue is the desired result. Obviously, one would need to monitor the smokey embers to avoid a flare up of flames and the loss of ones several days work.

The chemistry escapes me. For those with knowledge of what the brains (with their oils) does to the hide (made up of collagen, a fibrous protein), please comment with some chemistry!

Some references:

Basic brain-tanning:
http://amohkali.com/files/tancourse.pdf
http://www.native-art-in-canada.com/tanninghides.html

Tanning chemistry:
http://www.conservation-wiki.com/wiki/Books_Section_4_-_Material_-_Chapter_1._Animal_Skin/Leather

Industrial tanning chemistry:
http://nzic.org.nz/ChemProcesses/animal/5C.pdf

Historic Ironworking

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One possible set of developmental steps in the the use of iron.

If one is writing (alternative/)historical fiction, it’s important to get the technology developed in a believable sequence. Iron is a highly technical product and deserves attention in any fiction.

Iron ore is a chemical compound of iron (Fe), oxygen (O) plus impurities.

Bloomery

In this earliest step, air is forced through a mixture of iron ore and charcoal (think of the poor apprentice working a bellows for hours on end). One of the byproducts of the burning charcoal is carbon dioxide which reduces the iron oxide to iron. Typical bloomeries do not reach a hot enough temperature (only 1000 degrees or so) to actually melt the elemental iron. Hence it ends up as a spongy mass called a bloom. The pores of this bloom is filled with ash and slag. Pretty useless until it is reheated and repeatedly beaten to join the iron particles and force out the slag and ash. The result is called *wrought iron*. It was a very labor intensive process. But the early ironworkers probably developed a nice set of muscles.

Carburization

Wrought iron was fairly malleable (soft) metal. Heating in contact with carbon (charcoal again) allowed carbon to migrate into the outer layer of the metal. Quenching in water (or oil…think more carbon) froze the carbon in that outer layer. Now one can get a hard out layer (especially a cutting edge) with a softer inner core (producing a less brittle tool or weapon).

Crucible Steel

The wrought iron, even if carburized, is still soft. If a mixture of wrought iron, charcoal and glass is encased in a clay crucible and heated, the carbon migrates into the iron and the glass forms a protective slag.

Cast Iron

If the iron can be mixed with a lot of carbon and heated to 1140 degrees, the iron is liquid and can be poured into molds. The high carbon content however makes the iron brittle.