Ed said:
ummm.... I'll have to try that. I've never bothered boiling my nettle skins .... just gave them a quick soak in warm water to free up the fibres. I do boil willow (inner) bark though as this really does improve the fibres for cordage. Willow contains quite a few different acids, and boiling in a lye solution will neutralize them. You also get a nice colour change to a deep red/brown when it is done.
Ed
Torjus mentions boiling to allow the tannins to both strengthen and preserve the fibres once removed, not just to facilitate removal of the unwanted softer tissue.
Tannins are soluble in water so this makes sense, like adding boiling water to tea leaves releases tannins, amongst other things, that gives tea it's slight astringent taste. I guess the amount of boiling would be to allow sufficient break down of cells to release the tannins. Not ages I guess. leaving them to soak for a while would help too.
Once the fibres have been removed from the nettle (or indeed finished cordage?) they could be also 'treated' by boiling in a solution made from boiling nettles or other tannin rich material (oak leaves or bark for instance, especially towards the end of the season). The idea would be to allow the tannins to soak into the fibres (protein structure?), thus providing the cordage produced with additional strength (not sure how that works) and longevity, i.e. to deter insect and fungal attack(tannin having anti-bacterial and insecticidal properties). This would be more important in a finished product such as a fishing net which will get repeatedly wet etc.
I think treating the nettle in lye would strip the nettles of the soft outer tissue and aid separation of the inner fibres, but this would also remove the tannin (being an polyphenol/ acid) and it's properties? Also I seem to remember Toddy saying that this would weaken the cordage produced too.
I also suspect that treating with tannin would make the eventual fibres/ cordage more subtle as they would break down the cellular structure somewhat. As it does with leather. Just a guess though.
A natural way to aid preservation in cordage is to apply beeswax which helps inhibits desiccation and it has anti-bacterial qualities too. It might make the net float though!
One of the first lessons in rigging a ship model is to draw the cordage through a cake of
beeswax to lay down the fuzz, or loose surface fibers. But theres more to it than that;
beeswax is a fine natural preservative which inhibits desiccation (drying) of the thread
fibers, thus prolonging the life of the cordage and preserving its pliant qualities. The
problem with drawing thread through a hard beeswax cake is that the wax forms only a
surface coating: the core of the thread remains untreated, and worst of all, the lay of the
thread is usually filled with wax so it is no longer easily seen and an important aspect of
realism is lost.
The way out of this problem is to dissolve the beeswax in solvent such as turpentine or
xylol, then draw the thread through a wad of cotton soaked with the wax solution. A
fresh cake of beeswax should be cut into small flakes, then placed in a small jar of
solvent; as much wax should be added as will dissolve in a day or two. The solution
should then be filtered by pouring it through cheese cloth. Id addition to treating new
thread as above, old rigging on models being cleaned or repaired can be waxed in situ by
applying the solution with a brush. Serving, seizings, and splices can be waxed and rewaxed
in similar fashion.
source:
http://www.ship-modelers-assn.org/tps0508.htm
