|
Hi DJ,
So now I can help YOU. Those spots are called
"fish-eyes". There are a number of causes and this, too, plagued people
back in the 1800's. They had different explanations for it. I find
that some pigments are oilier than others--yellow rarely fisheyes for me but
magenta does often. I thought this was because I was usually using magenta
as my last layer and thus there was a slicker surface of exposed gum layers
below to make it fish eye, but when I use magenta as my first layer it does
it.
You may be right in that your sizing is causing
this, either by unevenness or that the layer is a bit oily. How to get rid
of them is let the layer set for a few seconds and then brush, brush, brush,
say, with a dry hake brush to even them out. This sometimes
works.
Otherwise, make sure your gum mix is not too
liquidy, because when my coating solution is less viscous this happens more
often. So you might try adding a little gum powder to thicken the layer so
it doesn't separate.
As a last resort, do your gum print and fill in the
missing color with Prismacolor color pencils when the gum print is
finished.
One 19th century explanation talked about at length
in the British Journal of Photography was that when the dichromate was added to
the gum/pigment, little balls of insoluble gum (like fish eggs) would form and
"part the waters" so to speak. One man professed to see it under the
microscope, these little globules. Who knows if this is correct, but it
seems a bit far fetched.
I sympathize with you because fish eyes are a
PAIN.
Chris
__________________
----- Original Message -----
Sent: Sunday, September 07, 2008 4:59
AM
Subject: question on sizing
dear list members,
I'm a novice at all these processes, so
maybe you've encountered this problem a thousand times allready, but maybe you
guys (and gals) can help me out:
for tri-colour gum printing, I size my
paper. Although I don't think my paper (Arches Aquarelle, 300 g/m, i use both
cold and hot pressed) doesn't really need sizing, I last found this paper from
bamboo that I like, that actually does need it.
I size with a 3%
gelatin solution, with glyoxal as my hardening agent. After drying (single
coat of gelatine-size), I notice that my gym/pigment/dichromate solution
doesn't really stick on some small parts of the paper. When I use non-hardened
paper, I need more of the gum-dichromate solution to coat my paper (but I
don't actually mind this.....). On the hardened paper, I need less volume of
gum-chrom. solution. But in general, it works fine, but there are (often)
small parts, where the paper looke tike it 'rejects' the solution. Don't
really know how explain this, but it looks a bit like the paper on that
particular spot, doesn;t absorb water-like soltions).
Does any one have
any ideas on this? How to size in a way that these spot son't occur any more?
Or is sizing on Arches Aquarelle perhaps not even necessary (an idea that I
would really like, since this sizing stuff is really boring....)?
Would
love to hear your ideas on this issue!
kind reagrd,
DJ
|