I thought you might be interested to know that rubber manufacturing
is not as bad as you feared -- it's worse!

Here is what I learned about composition rubber manufacturing at
a company that makes the stuff for shoes.  (My wife was a quality
engineer there for a brief time.)  They mix gum rubber, polystyrene
(and maybe other plastics), carbon black, and something like clay, in
an attempt to get a product that they'll sell to shoe manufacturers for
making the soles of shoes.  So far, so good.

The problem is that sometimes it comes out too gummy, or too granular,
or with the wrong viscosity to mold right when melted, or various other
difficulties.  The guy who runs the company is an accountant, and he
values partially-completed product at the level of labor and materials
already put into it.  Thus a bad batch that's been re-worked a couple
of times is "valuable" and not something to be thrown out lightly.  So
what he has his company do is to add some of the bad batches to each
new "good" batch, thus avoiding having to write it off as waste.

The result is, of course, exactly what you would get if you had ten
barrels of good wine and one of sewage, and tried to salvage the sewage
by mixing one part in ten of it into the wine.

I cannot believe that the manufacturers of rubberized cloth behave any
better than those of shoe rubber.  Raw materials specifications are
routinely ignored, or often do not exist.  Mixing methods are "whatever
works today."  Because consistency is not their hallmark, good material
may frequently slip through, even though their general methods are
crummy.

Peter Neilson

 [ I occasionally get a good bottle of cheap wine...!  ;)  -- Robbie