Guy Glorieux asks
> Hi friends,
heya!
> Happy New Year and happy celebration to all who will be participating
> physically or in spirit to the inauguration of President Obama!
woohoo!
> The question has to do with the tratment of over-exposed prints and the use
> of reducers, such as Farmer's. Does anyone have experience with the
> chemistry and the results which they would care to share with me?
>
> I need to reduce the density (both overall and as a minimum the highlights)
> of several of my giant pinhole prints created several years ago. These
> portray urban landscape scenes that have permanently disappeared and I am
> trying to resurrect the paper negatives. As such, these are one-only prints
> and I cannot afford failure if I try to reduce them. I will be working with
> over-sized trays - 5 feet by 2 feet by 6 inches - using the
> roll-unroll-reroll process. I need about 4 gallons of working solution to
> work confortably in the trays and I will mix my own recipe using Steve
> Anchell's celebrated Darkroom Cookbook.
below is my list of bleaches ..
A:
Hydrochloric acid (30% solution) 200ml
Copper sulphate 200g
water to make up to 1 litre
Dilute the bleach 1:10 - 1:50 for use and *soak prints* before placing them in the bleach to ensure consistent bleaching.
Fix after bleaching then wash.
Positives: Clean acting bleach with NO staining. Downsides - etches lighter tones more aggressively than darker tones. the Oh-oh! redevelop point is pretty much missing with this bleaching process..
B:
Potassium Ferricyanide 50g
Potassium Bromide 50g*
Water to make up to 1 litre working strength
Wash thoroughly before fixing ('till any yellow stain is gone), then fix, then wash again. This is basically the 'split' farmers process with benefits that the farmers process doesn't have (below) - farmers mixes the bleach and fix to make things more convenient but it has drawbacks.
Positives: Clean acting bleach with NO staining if washed thoroughly before bleaching. Also if you've gone too far in your bleaching you can redevelop to get the image back :) Downsides - as with Farmers it can stain prints a faint yellow colour.
C:
water 500ml
Potassium bichromate 5g
Hydrochloric acid (35%) conc. 40ml
water to make 1l for use
Fix after bleaching then wash.
Positives: bleaches evenly and doesn't stain. Cheap.
D:
Potassium permanganate bleach
Part A
5g potassium perm & water to make 1l
part B
Hydrochloric acid 80ml & water to make 1l
add 1 part A & 1 part B & 6 parts water prior to use. This bleach is suitable for re-bleaching prints that have previously been sepia toned. Some staining may occur so this should be removed by soaking the prints in a 1% potassium bisulphate solution then washing.
fix and wash.
Positives: removes any yellow toning from residual fix residues, removes sepia toning. Downsides: can stain like mad if you are not careful or have not mastered it by careful experimentation first!
E:
Iodine reducer
Potassium iodide 16g
Iodine 4g
water to make 1 litre
dilute the stock solution 1:20 for use. After reduction rinse well then re-fix, washing well after fixing. Some staining may occur, removable by soaking in a 5% sodiuum sulphite solution.
Positives: it's a bleach Downside: expensive, stains often, expensive.
my favourites are B and C though I often use A just for fun..
I'd also suggest wetting the prints thoroughly before any bleaching and maybe selectively reducing any areas that really need it before doing the whole print
hope this is of some use!
Karl
