U of S | Mailing List Archive | alt-photo-process-l | RE: a few notes on my first few gum prints...

RE: a few notes on my first few gum prints...

I agree the hake brushes are terrible – depositing hairs as well as having no feel to them. (They are useful for brush development in cold water though.) I use [for 8x10 prints] a 2” watercolour ‘resable’ brush – not expensive but I’ve been using the same brush for over a year now (maybe 100+ prints) and its never lost a hair [unlike me] and still has plenty of spring to it [er … also unlike me].


Coating is a fun game. I never use a dry smoothing brush – when I tried it made things much worse.


I print with gum or PVAL. They have different characteristics and require different techniques – as will gum with different amounts of dichromate. Gum and equal amounts of 13% dichromate is a wet and runny liquid which I find goes smoothly and easily onto dry paper. PVAL and equal amount of 5% dichromate has similar printing times but is a much more viscous liquid. Tricks I have found useful are (1) wetting the brush (but removing excess water) before use, (2) dampening the paper – helpful for more viscous mixes, (3) using a softer watercolour brush for more liquid mixes, (4) allow the gum print to self-heal – repeated thin coats hide a lot of unevenness in a single coat.


Coating also seems to vary according to the layer you are putting on: a first layer of yellow/sienna is always perfectly smooth but intermediate layers of heavier pigments can be more problematic.


Incidentally I print from a single negative: if you’re trying to do 3-colour separation prints in a similar number of layers then you’re problems are greater.


Geoff Chaplin

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From: Paul Viapiano [mailto:viapiano@pacbell.net]
Sent: 04 July 2009 15:36
To: alt-photo-process-l@usask.ca
Subject: a few notes on my first few gum prints...


Hi all...


First of all, thanks for all the suggestions and comments on my first tricolor gum. It was definitely a good learning experience for me.


There are a few things that I noticed while working that I hope to clear up and solve.


One, is the use of hake brushes. I've been using the inexpensive variety found at the typical art store, about $2-4 each. Coating is difficult with these because there is absolutely no spring to them, they just go limp and the hair goes every which way even brushing lightly. I know how to coat pt/pd and am always successful when coating that emulsion. Gum, although more viscous than pt/pd should still flow on quite easily.


I know that the gum coating should be on the thin side, and my guess is that for a 4x5 print I should be using approx .5 - .75 ml of solution, but those hake brushes are horrible, very hard to get an even coating, at least consistently for me.


I'm very tempted to try a synthetic watercolor wash brush as I use for pt/pd (DaVinci Cosmotop). Expensive, yes, but the perfect brush for pt/pd. Just a dip in distilled water, a shake or two, and it's good to go. I bet it would really make for a nice smooth, even and just-right gum coating using the same technique.


Here's something else...I notice that Sam Wang, in his gum article on Unblinking Eye, brushes on his gum coating and doesn't use another dry brush to smooth it. I'm thinking of trying this as well, as long as I can get a really smooth, even coat down with a good brush.


One of the things I noticed was that while burnishing my coating with a dry brush, it started getting very grainy looking. I'm thinking that I could keep the smoothness if I just brush on once, nice and thin, and don't use another brush to burnish and dry.


Today was a disaster...I started on another tricolor print and upped the ratio of pigment to gum, to get darker colors and it all devolved from there. It happens, I'm experimenting...this has all been seat-of-my-pants stuff but now I need to do a few test strips with a consistent pigment/gum ratio to get a good starting point and figure out the smooth coat/non-grainy stuff, too.


Comments and criticisms are most welcome. I'll report back, if y'all don't mind, on my progress and findings...


Happy 4th to everyone here in the US and much thanks to all who weighed in from around the globe as well...