From: Clay (wcharmon@wt.net)
Date: 07/24/03-06:41:55 AM Z
>
Katherine wrote:
> The reason I referred to
> a "mystique" associated with the practice is that when Dave asked a
> reasonable question: what's the difference between putting the
> dichromate dry into the gum and then adding the water, versus mixing
> the
> dichromate solution first and adding it to the gum that way? his
> question was dismissed with a reference to all hat and no cattle.
First, I must apologize to Dave (and the list) for the stupid crack.
Arrested development, early AM lack of caffeine, and personal respect
for Stuart (he is the complete antithesis of a self-hyping individual)
led my keyboard fingers to leapfrog my brain.
That said, I DO NOT think it some mystique: in fact, I still use
saturated solutions in many cases, depending on what I want to achieve.
But the bottom line is this, if you have ammonium dichromate in a
completely saturated liquid solution which is added to a coating layer,
the amm. dichromate solution volume will, by necessity, contain roughly
2/3 water, regardless of the volume added to gum plus pigment. By
adding dry dichromate to the gum directly, you can greatly reduce the
total amount of water in the mix, and increase its viscosity, which can
lead to some extremely smooth coatings. This may not be something
desirable for everyone - I don't know. And the point that after the
layer is dried, and the water has evaporated, it is basically the same
is also true. But the real benefit, IMO, comes in at the coating stage
because the viscosity of the solution allows (actually, pretty much
demands) a different mechanical procedure to be used to lay down the
coat. I can say with certainty that laying down a layer done this way
versus using a saturated solution IS different, and it is worth trying.
It may not float your boat, and it may seem unnecessary to the way you
work.
I am not saying this is the one true way or anything like that - in
fact, I still like using a brush and doing it the traditional way from
time to time, because it makes me feel so .. well, artistic, what with
the brush and beret and little goatee and all. But really, the thing
that set me off was the a priori criticism. If you're curious, try it,
and see what it does. You may hate it, you may love it.
Beret in hand,
Clay
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