MtMan-List: Re:rubber ponchos

[Jim Colburn <jc60714@navix.net>]

Washtahay-
At 03:58 AM 11/3/98 -0600, (John, you really should sleep sometime) you wrote:

>snip<
>Rubberized cotton canvas of modern manufacture would probably be as close as
>anyone could get commercially today.  It wouldn't be much different than what
>was made before 1840.  More common today, I would suspect, would be a
>synthetic
>rubber which should offer no functional difference.  Perhaps better wearing
>qualities.
	Back in amongst the many myriad misspent days of my youth (probably 10
years ago) I had a job at a plant that manufactured rubber products to spec
for various purposes.  We had a lot of rubber, chemicals, etc, and I
probably spent too many hours playing...  
	Anyhow, a cotton weave fabric treated with natural latex isn't really very
durable.  The fabric seems to tear more readily.  (Some of the latex we
received was smoked to preserve it, if anyone runs across it, it isn't
necessarily treated with sulphur or vulcanized in any way.  I was told this
was done to reduce problems with spoilage.)  Also, the latex treated fabric
was rather "tacky"-not as much as a new tack cloth, more like the one I
usually forget on the benchtop for a week or two.   
>
I have not had any rubber I was certain was not vulcanized to
>determine if would have the strength for use in pure sheets to be practical.
	The pure latex I had access to was very susceptible to punctures (and
tears at the edges) when in an unsupported (no fabric) sheet.  If
unvulcanized latex was used in this manner, I suspect it may have been
placed on or between pieces of canvas.
	All in all, they were fun experiments to run, but the possible health risk
would make me suggest using extreme caution if you try to experiment along
these lines. 

>I have not encountered exact reference to colors finished goods may have been
>traded in, most recipes call for black or brown pigment. 
	It is fairly simple to amalgamate carbon black into the raw latex.  It is
doable with the technology of the 18th century-but I don't know if it was
done.  

> Yellow would have
>been possible though not nearly as bright as the items you mention.  Yellow
>Ochre --- maybe. 
	If ground to a fine powder, it works.  Looked more like dried
mustard-nothing at all like a fishskin.
>
>I am not presently aware of a source for pure natural India rubber.
	Given my above caution, if anyone is really interested I can try to point
you in the right direction.
>
LongWalker c. du B. (and itinerant alchemist)