"George Adams" wrote in message
...
From: (Goat)

Now the Cab-o-Sil is not quite so easy to get but I will give it a try
as well. Found some online for $5.20 for 1 gal. The Cab-o-Sil is a
powder correct? Does it protect againt the water saturating the fly or
does it just dry out the flies fibers (or both)

There may be more than one type of Cab -o- Sil. (see Larry L's posts on
this
thread) The one I purchased was from Spruce Aircraft, and I think it was
more
expensive, but I might be including shipping charges. My memory ain't what
it
used to was, and I discarded all the info I had long ago.

In my experience, it dries out the fibers, and also acts as a floatant,
but
it's main advantage is as a super dessicant that will dry out delicate
fibers
like CDC and ostrich herl. The trick is to work it into the fibers
completely
with a brush. You may want to consider purchasing one container of FF to
get
the supplied brush.
...

I just did a little experiment.

I put about half an ounce of water in a glass pinch bowl and then added a
pinch of Frog's Fanny. The FF floated in clumps of various small sizes.
After stirring vigorously for a couple of minutes, all of the FF was still
floating. Twenty minutes later, all of it is still floating.....or, at
least apparently so. None is visible below the surface. Without chemical
analysis, it's impossible to tell whether or not any has dissolved.......but
I don't think it has. What does this mean? Well, it looks like FF is not a
desiccant, at least in the sense that silica gel or clay (two of the most
widely used desiccants) are. Both clay and silica gel work by absorption.
They are both porous and hydrophilic. That is to say, they readily form
loose bonds with water molecules and have a large available surface area
with which to form many such bonds......they hold a LOT of water. Drop
either of them in water and, even if ground exceedingly fine (like FF) and
they will sink because both are heavier than water AND their hydrophilic
character allows them, even in very small pieces, to break the surface
tension......they sink

FF seems to work by aDsorption, as opposed to aBsorption. Adsorption is
purely a surface phenomenon. FF works because water clings to the surface
and then is brushed off with the excess FF. Drop a saturated fly in a
bottle of FF and you will pull out a saturated fly covered in FF.

Bottom line.......Frog's Fanny is not a desiccant.....nor, it seems, exactly
a floatant either. Or, at least not a floatant like most that we are
familiar with. It doesn't appear to absorb water like desiccants. Thus,
anything that is thoroughly coated with it won't absorb either. But it
doesn't cling to fly tying materials like all of the hydrocarbon based
floatant materials we're used to......and thus, it doesn't last long either.

I did another experiment. I don't know what "fumed" silica is, but I DO
know what silica is. Silica is silicon dioxide.....two oxygen atoms bonded
(very tightly) to one silicon atom. Silicon dioxide is THE most common
substance in the Earth's crust (remember OSiAlFeCaNaKMg?)....rock, sand,
quartz. Silicon dioxide won't burn.....burning is combustion, is
oxidation.....the silicon in silicon dioxide is already as oxidized as it's
ever going to get. I put a liberal shake of FF on a piece of paper towel,
and set fire to the paper. The FF survived, unscathed. Whatever this stuff
is, one simple test confirms that it COULD be silica.

Is there a mineralogist in the house?

Wolfgang
ain't science fun?