View Full Version : Salt print problems

04-24-2006, 02:15 PM
I tried my first few salt prints today. Along with first trying the process, I'm experimenting to see if potassium bromide, or a mix of potassium bromide and sodium chloride (in place of the plain sodium chloride) will produce a faster print (since silver bromide is supposed to be more sensitive, and over a somewhat broader range of wavelength, than silver chloride).

Unfortunately, I ran into two problems. First, all three prints fogged some (light brown stain before light exposure) by the time the 12.5% silver nitrate solution had dried (in the dark). This fogging has a distinct mottled pattern that matches the cold pressed surface of the paper. Could this be chemical fogging due to something in the paper (Canson Montval watercolor paper sold unsealed in a perfed 9x12 inch comb-bound pad)? Something in the bristles of my brand new hake (it seems identical to the fogging I got when I coated silver nitrate on untreated paper with a "chip brush", intending to follow with ferric ammonium citrate for what I hoped would be simplified VDB)? The silver nitrate was shipped to me in a clear plastic bag, but I wouldn't think any light exposure before making up the solution would affect the halides deposited from that solution, since any metallic silver formed in the original nitrate from light expsoure would have been left as solid rather than taken up in solution. Drying the paper after the salt bath required placing it on a blotting sheet (old towel), rather than hanging it; could this have removed enough salt to leave unreacted silver nitrate? Would I possibly gain by using stronger salt solution?

Second problem, all three prints darkened considerably in the wash, suggesting that they were very incompletely fixed -- I fixed for two minutes in 5% plain hypo at room temp (low to mid 70s F), then gave two minutes in 2% sodium sulfite clearing bath before going to the wash. Longer fix needed, I presume -- how much longer is enough?

Preliminary results, at low confidence level: little if any speed difference, at least under BLB exposure, between 2% NaCl, 1% NaCl with 1% KBr, and 2% KBr as salts in pretreating this paper. Low confidence because there was enough fog underneath the printing frame's masking leaves to make it hard to interpret the actual exposure-induced density. All three prints gave nice density in non-negative areas oustside the frame's mask, but reduced considerably in the fixer, the printed-out image losing contrast relative to the fog.

BTW, I also experimented with dropping a half teaspoon of potassium ferricyanide into the hypo (250 ml) after finishing with the prints, and using the resulting (very weak, improvised) bleach, similar to Farmer's Reducer, to remove some silver stains in the bathroom sink. Conclusion: it works, but needs stronger solution to attack the heaviest marks. I'd try dichromate bleach, but I'm not very comfortable with putting that stuff directly into the drain, nor (given the toxicity of dichromates) with the kind of handling that bleaching the sink requires; I'll come back with stronger hypo (maybe 15% as used for film fixer) and about 5x as much ferricyanide, and improvise some sort of dam to let it stand on the stain instead of swabbing with a soaked paper towel.

Side conclusion: looks like it should be possible to apply salt printing to unglazed porcelain and create an image embedded in the surface (the stains in the sink won't scrub off); seems to me I've read of something like this used to create those "photo tombstones" sometimes seen in graveyards from the late 19th or early 20th century.

04-24-2006, 03:29 PM
IM: I coated up a batch of sheets not long ago on three papers. All three were coated under dim tungsten light and dried in the dark at the same time. One paper (my favorite Fabriano Artistico) showed no sign of any fog. One paper (a Southworth resume paper) showed a very slight, almost not noticeable fog which did not prevent the exposing and fixing of a good image. One paper (Strathmore Aquarius) fogged to a medium brown color - about half the density of a fully exposed image. I have noted some of the same kinds of things with Mike Ware's new cyanotype formula - some papers do not like it. I have had very good luck with 20 grams NaCl per liter for salting and a 12% silver nitrate solution.

I have been fixing in two baths of plain hypo - 150 g per liter of distilled water. I mix up a liter and use half in each bath. Each bath gets 4 minutes. This is based on James Reilly's Albumen and Salted Paper Book. This seems excessive to me. Wynn White recommends 10% hypo in his description of the process on alternativephotography.com, and a search just now on 'fixer for salt prints' scared up a Sandy King post that recommended 5% hypo. I have been mixing in two grams of sodium carbonate, and in some places sodium sulfite is also recommended.

I have not noticed any darkenening in the final wash at all - there is a little dry-down darkening, but the prints do not change after the fix in either the clearing bath or the wash. I always switch from the dim incandescent to the full blast fluorescent lights once the prints are past the fix.

The salt print reducer recipe that I will be following (after I receive my next Artcraft order) includes potassium ferricyanide, potassium bromide, and hypo. I don't have the recipe in front of me, so I can't tell you the concentrations.

In my Artcraft order, I also purchased a gram of gold chloride, so I will soon be toning my salt prints before the fix. I hope that this will eliminate the lightening of the image in the fix, and give me more control of the color of these lovely prints. (There's also some ferric ammonium oxalate in that box, so cyanotype rex is in the works).

04-24-2006, 05:09 PM
Here's a quote from Liam Lawless on fixing of salt prints:

The fixer I used to use is as follows. With a sufficiently contrasty neg
(and sufficient exposure!), it should give excellent results.

Sodium thiosulphate (cryst.) 100g
Sodium carbonate (anh.) 10g
Water to make 1000ml

Some fixer recipes I've seen include a few grams of sodium chloride, the
purpose of which is presumably to convert any silver nitrate remaining at
the fixing stage into chloride, preventing staining if you haven't gold
toned first (toning after the fix also works). I didn't find salt
necessary, or that it made any difference, but it is important to wash quite
well after printing (10 minutes or so), as residual silver nitrate can cause
stains in the gold or hypo bath.

This is from the alt-photo-process archives: http://www.usask.ca/lists/alt-photo-process/2000/jun00/0280.htm

04-24-2006, 05:39 PM
Yep, I found the "Salted Paper and Albumen Book" after posting here -- I didn't wash before the hypo, or between hypo and hypo clear (sulfite bath), so I need more trays (problem -- small bathroom counter, need an alternate location for the black light and printing frame if I'm going to get 3-4 trays on there -- extension cord will get those over to the commode, I just have to figure where to clamp the black light lamp over there). Looks to me as if 10% hypo with salt added could sub for the pre-hypo wash; I'm not toning yet, and given the price of gold chloride or chloroplatinate, won't be any time soon unless it's something like a thiocarbamide sepia tone. So, next try will be:

100 g hypo
10 g sodium carbonate (converted for the monohydrate I have)
5 g sodium chloride (insurance against residual silver nitrate)

And fixing 4-5 minutes in each of two baths, then a wash (one tray, fresh water for each print) before going into hypo clear.

I also read that very porous or absorbent papers like watercolor paper need a heavy size or they give flat prints due to absorbing too much of the coating, so I picked up a pad of bristol paper today -- very smooth surface and takes water-based paints well, though I'm sure it'll rough up during the soaks in various chemicals and washes. Should be good for detailed cyanotypes even if it doesn't work well with silver processes. I might also try some heavy laser printer paper I've got, semi-glossy 90 lb stock that looks really nice with a color inkjet image on it.

BTW, anticipation of the results above (prints fogging before the silver coating is dry) is why I've been reluctanct to order the "extremely nicely priced" papers from various Internet vendors -- drop $50 for "bargain" pricing from a bulk purchase of some fancy paper I've never heard of, pay through the nose for shipping of a very large, flat package, get 20 huge sheets in, have all sorts of fun cutting it to a useful size and figuring how to store it where it won't collect dust, and then find out it doesn't work... :P Even Arches Platine is said to just not work well in some processes...

04-24-2006, 05:46 PM
One paper (Strathmore Aquarius) fogged to a medium brown color - about half the density of a fully exposed image.

Well, I'm glad I didn't shell out for the Strathmore today, then -- the local Hobby Lobby has four brands of watercolor paper: Arches Aquarelle, in single sheets only (between $4 and $7 per sheet, and the shelves all mixed up so I can't be sure what I'm really getting), Canson Montval, which I now know works poorly with silver nitrate, Strathmore Aquarius, and something cheap called "Impressions" (probably similar to the Malay-made cheap stuff I used when I started making cyanotypes last year). That's two out of the four that are known not to work and play well with silver.

What do you suppose could be in these papers that causes the silver to reduce spontaneously? Buffers? Something in the sizing?

04-24-2006, 08:15 PM
IM - I don't think that you can skip the water wash before the fix. Salted paper has a tremendous excess of silver that needs to be washed away. Wynn White's description of his method includes 8 trays of water with a pinch of citric acid in each before the paper goes into the fix. My setup for salt prints uses six trays - citric acid wash, fix, fix, wash, hypo-clear, extended wash in running water. Most of the descriptions of the process that I have read seem to indicate that the pre-fix wash step should not be skipped or cut short.

The following quote is from an article by Liam Lawless on POP paper, which is similar to salt prints in most respects http://unblinkingeye.com/Articles/POP/pop.html

Before fixing, prints must be washed for 10-15 minutes, until free of any remaining free silver nitrate; washing only until the water no longer looks milky is not sufficient. Failure to wash adequately results in general staining that resembles fog - not usually heavy, but increasing the length of the tonal scale and giving grey highlights. It normally appears, if it does, during the final wash and the reason is probably the formation of light-sensitive silver-thiosulphate compounds by silver nitrate carried into the fixer.

04-25-2006, 02:16 PM

Eight, or even six trays is simply not on in my tiny temporary darkroom, even if I owned eight trays (well, I do, I own nine, but 5 are 8x10 and the other four are 16x20; there's room for precisely *one* of the latter on my counter and it takes a gallon to fill it decently). Time to shop around and find something that can sub for a 4x5 or 5x7 tray, and get a half dozen or so.

I can probably manage to use one tray for the first wash with a pour-in, pour-out wash cycle, from a graduate of pre-acidified water (I did get some citric acid and tartaric acid at a local brewing supply this past weekend), then return to that for the wash before hypo clear. Fog formation in the final wash is *exactly* what I was seeing, a black overlay on the brownish image and pre-exposure fog.

I wonder if a pre-wash in salt water (to convert the silver nitrate to silver chloride) would let the fixer clear it out without requiring a running water or multi-tray wash? Guess I'll have to try it. Need to salt some of the bristol paper tonight; might do a few sheets of the 90 lb cover stock as well, and might even (as insurance) try floating a few sheets of plain copier bond (that I use in my laser printer), since the descriptions and illustrations of the floating tehchnique strongly suggest the paper should be thinner and more flexible than what I've been using (more like typing or copier paper than, say, the base for RC photo paper). Gotta find a place to dry the stuff, too...

I say again: Ack.

04-26-2006, 09:44 PM
I didn't read all the previous comments but I would like to add a comment regarding the number of trays used. I hope I'm not speaking out of school here and if I am just tell me.

With van dyke I use only one tray. It's a plastic dishpan tray I got at target for a couple bucks. I'm not familiar with salt prints so don't know if this applies.

1. wash print, when through dump out in sink. The paper clings to the bottom of the tray so no problem.

2. pour in appropriate amount of toner, when through dump in sink or back into container.

3. pour in fixer, when done dump out in sink or pour used into container.

4. pour in hypo clear, when done dump out in sink.

5. pour in water for wash and wash app. amount of time. I usually wash in static baths and change water 5 or 6 times.

Theres no rinsing between steps, just dump one out and pour the other in.

FWIW Just thought I'd throw this in. It could save you some counter space.

05-06-2006, 12:04 AM
Thanks, buggy, I'm now using a variant of that. I did find today that prints washed before fixing in approximately 2% sodium chloride solution showed no sign of blackening in the wash, while a couple that I did without the salt (which I thought was fading the print) show no less fading but lots more bladkening after washing.

However, I'm making progress -- I know more things that don't work.

Wausau Exact Glossy Coated (inkjet paper for photographs) curls like mad when I apply the solutions, which made me think it might be gelatin sized, but it doesn't stand up well to being wet long enough for processing (blistering, the two coated layers coming apart), takes up too little chemical to give good density, and fogs a bit.

OTOH, Strathmore Bristol seems to be a big improvement; still non-zero fog, but it's not bad at all, took enough chemical (drip-and-brush for both salt and silver) to print to a full, rich black, which then softened to a rusty brown in either the salt wash or the fixer. Highlights are almost white, quite acceptable. And it holds up pretty well in the processing; not much worse than some fiber base silver gelatin papers (after washing for two hours, no sign of separation, though it did peel and edge crush a bit when I worked a fingernail under to get it off the bottom of the tray). Even dries almost flat!

I'm not toning yet -- gold chloride is a little out of my budget, and I'm not very happy with the idea of using selenium where I have no way to dispose of it properly -- but I need to look at formulae a little more and see if I can do something to cut down on the reduction of the print in the pre-wash and fix. Meantime, I'll have to try some VDB rex on this paper... :) Attached files http://f295.f295.org/uploads/03saltprint_5824.jpg (http://f295.f295.org/uploads/03saltprint_5824.jpg)

05-06-2006, 06:59 AM
Hey, now you're talkin', Don. This has that WHF Talbot air about it. Isn't it fun to make 150 year old prints with your own negatives?

05-06-2006, 09:37 PM
Any paper made for digital processes has the potential for freakish chemistry.

There are countless proprietary processes for digital papers now including clay coating of all things to make them hold ink, dry & not bleed.

We have run into dry mounting issues with mystery materials people bring in, thinking it's ' a photo'. Some of them seem to have the ink just suspended on the surface.

If you get good results, I guess I'd be the last to say 'don't do it'. Personally I'd either avoid or try to get technical info to the extent the papermaker will tell you if I had an inkjet paper.

05-06-2006, 10:44 PM
Murray, the inkjet paper didn't give good results -- fogged and didn't hold chemistry (I now suspect it is in fact clay coated, like the paper in a glossy magazine, specifically to keep the ink from penetrating and spreading). The Strathmore Bristol that gave good results is a common art paper touted for mechanical drawing, pencil, pen and ink, and airbrush. It's marked as acid free, but apparently doesn't have whatever is in Canson Montval watercolor paper that makes that fog so badly.

Given the price and the results to date, I'll be using the Strathmore Bristol for the foreseeable future.

05-06-2006, 11:35 PM
I'm gonna need to get some Strathmore Bristol. It sounds like a good paper.

The wooded area print above is very very nice indeed.

I just re read this whole thread and saw your comment about adequate washing (clearing) before the fix. I have been experiencing muddy highlights lately and thought I was washing long enough but maybe not. I usually go around 10 minutes but maybe I need to do more like 15.

05-07-2006, 11:08 PM
Buggy, I was pretty pleased with a couple minutes in a 2% salt solution before the fix. The idea of the pre-fix wash is to ensure there's no residual silver nitrate, to avoid forming sensitive compounds that might remain after fixing. The salt bath converts all remaining silver nitrate to silver chloride, which the fixer can happily dissolve away. The prints I so treated showed no sign of blackening later, as others have when I didn't pretreat before fixing.

Salt's cheap, too, much cheaper than a bunch of extra distilled water (I don't use tap water for *anything* photographic, except washing prints). For this, you could even use table salt, rock salt for making ice cream, etc. instead of the more expensive high purity varieties.

BTW, I just found Strathmore Bristol listed as a good paper for VDB in Jan Arnow's (1982) Handbook of Alternate Processes (on loan from the library). :D

05-08-2006, 04:38 PM
I'm writing that down about the salt wash before the fix. In fact I'm gonna prepare that wash right now before I forget, that way I'll have it when I finish my current print that's cooking now.