Gold-borax toner

The other way to make a gold toner. Every other gold formula in this formulary reaches gold(I) with a sulfur ligand — thiosulfate, thiocyanate, thiourea. This one uses no ligand at all: four grams of borax, and time.

It is also the oldest architecture in the batch. The Getty Conservation Institute’s atlas records that most of the nineteenth-century toning recipes for collodion printing-out papers called for a borax-gold chloride solution, which is exactly what this is.

Ingredient	Quantity	Form the source specifies
Borax (sodium tetraborate decahydrate)	4 g
Chloroauric acid	8 mL of a 1% solution	printed as "gold chloride, 1% solution"; the kit supplies it ready made and the instruction is to add the entire contents of the bottle
Water	500 mL, added	at 38 °C; Distilled water at 38 °C. The kit states no make-up volume: the bath is 500 mL of water plus the 8 mL of gold stock, and the strengths on this page are computed against that 508 mL and labelled as such. A 500 mL brown glass storage container is specified for it.

Purpose

To tone a printed-out silver image towards blue, and to hold it through the fixer. The kit’s own phrase is alkaline gold toning, which will cause a shift in print color towards the blue.

The second half of that purpose is the one a silver-gelatin printer will not expect. A printed-out image is finely divided silver in a thin salted or gelatin layer, and a plain hypo fixer thins it. Gold plated onto the image before fixing is what survives the bath, which is why toning comes before fixing in every printing-out process and after it in every developing-out one.

Recommended uses

Salted paper and printing-out paper, which is what the kit is for.

Where a cold, blue-toned print is wanted. The kit’s colour direction is towards blue and it says the print gets colder the longer it stays in.

Where a sulfur ligand is not wanted in the bath. The thiocyanate toners dissolve finely divided silver while they plate it; this one has nothing in it that does. That is a real difference on a printed-out paper, whose silver is about as finely divided as photographic silver gets.

Where the bath is to be kept. The kit specifies a 500 mL brown glass storage container for it, which is a statement that the solution keeps.

When another formula is preferable

• Where warmer reds and maroons are wanted along the way, the gold-thiocyanate toner, whose colour path runs through them before it reaches blue, and which is published with a replenishment scheme.
• On a silver gelatin print, Kodak’s GP-1 for protection or T-21 for a brown tone: this bath is not published for developed-out papers and no source read for this course gives times for it on one.
• Where the toning must be quick. An alkaline gold bath is the slow route by design; Reilly records that a sodium acetate toner of this class generally needs twenty-four hours to ripen before it will work at all. This kit’s borax bath is used the same day, which is worth knowing as a difference between the two alkaline toners rather than as a contradiction.
• Where gold is not affordable. The kit’s own advice is to trim the print’s edges before toning to conserve the toner, which tells you what the constraint is.

Mixing

One bottle, warm water, two ingredients, in this order.

1. Distilled water at 38 °C, 500 mL, in the mixing bowl.
2. Borax, 4 g. Stir until the solid dissolves — this is why the water is warm.
3. The gold: the entire contents of the kit’s 1 per cent gold chloride bottle, 8 mL. Stir until homogeneous.
4. Into a 500 mL brown glass storage container.

The brown glass is not decoration. Reilly’s storage instruction for a gold stock, on the chloroauric acid page, is to keep it in the dark, because light reduces dissolved gold.

🧮What half a litre of this bath carries

The kit states no make-up volume; the liquid is 500 mL of water plus 8 mL of gold stock.

8 mL × 1% = 0.08 g, in 508 mL = 0.157 g per litre

Gold chloride

4 g in 508 mL = 7.87 g per litre

Borax

0.157 g of gold salt per litre, which sits inside Reilly’s published range for a matte salted paper — 0.1 to 0.2 g per litre — and between Kodak’s GP-1 at 0.10 g/L and its T-26 at 0.41. Four independent sources now agree on the order of magnitude of a gold toning bath, and this one is in the middle of the range for the paper it is sold for.

Reilly’s own borax bath, printed in the same chapter, is 0.4 g/L with 10 g of borax — two and a half times this one on both counts, and exactly his figure for glossy albumen. A kit sold for salted paper and a handbook written for albumen give different numbers for the same architecture because they are toning different papers, and the strength rule is what reconciles them. It is under Variants.

The borax is in enormous excess and is not a reagent in the usual sense. At 381.37 g/mol for the decahydrate it gives about 20.6 mmol/L, against the gold’s roughly 0.46 mmol/L: about forty-five to one. That is the ratio of a buffer to the thing it is buffering, not of a ligand to a metal, and it is the arithmetic behind the mechanism below.

Half a litre of bath contains eighty milligrams of gold chloride, which is why the kit tells you to trim the print before you put it in.

Behaviour

Six to twelve minutes at 21 °C, which is the only time and temperature published for this bath.

You cannot judge it wet. The kit is explicit: it is difficult to judge the end result of the toning until the print is fixed, washed and dried, and you will have to experiment to gain experience. The cold tone increases on fixing and on drying, so a print pulled at the colour you want will end up colder than that.

Longer is colder. In general the print develops a colder tone the longer it is in the toning bath.

The bath keeps. A brown glass storage container is specified, which is not what a supplier says about a solution meant to be mixed and discarded. No shelf life is published and none is invented here.

The intermediate wash before toning is part of the process and has its own rule. The free silver nitrate is washed out in a tray rather than under running water, changing the tray until one comes out that is not cloudy — and the kit warns against over-washing, because the image can be lost.

Toning may be retoned. The kit notes that prints can be re-toned after the final wash, provided they are re-washed thoroughly afterwards to remove the toning chemicals.

Image characteristics

Towards blue, and colder the longer it tones.

Colder still after fixing and drying, which is the property that makes this toner hard to learn.

The full scale survives the fixer, which is what the gold is for.

No warm intermediate stage is published for this bath, unlike the thiocyanate toner, whose supplier describes a path through red and maroon. Whether that difference is real or simply unreported is a good question and appears under Experiments.

The mechanism

This is Ware’s second route to gold(I), and it is the one with no sulfur in it.

⚗Gold(I) without a ligand

Gold in the salt you buy is gold(III), and silver oxidises only to silver(I), so a plain gold(III) bath spends three silver atoms for every gold atom deposited: it bleaches the print faster than it tones it, and Reilly’s description of that result is flat, lifeless and reddish. The equations are on the chloroauric acid page.

A useful gold toner works with gold(I), one silver for one gold. Ware gives two ways to get there. The first is a sulfur ligand — thiosulfate, thiocyanate or thiourea — which both assists the reduction and stabilises the product; that is T-21, GP-1, T-26 and the thiocyanate kit.

The second is a plain mild alkaline buffer — acetate, borate, carbonate or chalk — in which gold(III) slowly oxidises water instead, over as much as twenty-four hours. Borax is the borate. That is the whole of the mechanism of this formula, and it is why there are only two ingredients in it: one is the gold and the other is the alkali that reduces it.

Why the bath is slow, and why Reilly’s ripening figure is not this kit’s time. An alkaline gold bath has to convert its own gold before it can tone anything, and Reilly’s account of a sodium acetate toner is that it generally needs twenty-four hours to ripen. This kit gives no ripening period and a 6-to-12-minute toning time. The two statements are about different alkalis and different concentrations and the course does not reconcile them; what they share is the direction — an alkaline gold toner is the slow, self-reducing kind, and its rate depends on how alkaline it is.

How to read the bath. Reilly’s test, on the chloroauric acid page: the acid stock solution is yellow and relatively inactive, and as alkali converts it to the active state it goes colourless, so decolorisation is the best guide to the condition of the bath. Made too alkaline it tones faster but dies faster, and can end up holding plenty of gold while toning nothing at all, with no sign of it other than the toning stopping. That is the failure mode of this formula and it is invisible.

What the toning leaves behind, and why fixing follows. The chloroauric acid page notes it in one clause: toning in a chloride bath leaves silver chloride in the paper, so toning is always followed by fixing. The kit’s sequence — tone, then fix for ten minutes, then wash for an hour — is that consequence, not a convention.

Why no sulfur ligand also means no etching. The thiocyanate toners dissolve finely divided silver while they plate it, because thiocyanate is a strong silver ligand; the sodium thiocyanate page gives the formation constant. Borax does nothing of the kind. On a printed-out paper that is a real difference in what the toner does to the highlights, and it is the strongest argument for the alkaline route.

Function of every ingredient

Borax, 4 g, so about 7.87 g per litre. The alkaline buffer, and the whole reason this formula works without a sulfur ligand. In a mild alkali, gold(III) reduces itself at the expense of the water, and what is left is the gold(I) that plates one-for-one onto silver. It is present at about forty-five times the gold by moles, which is the ratio of a buffer rather than of a ligand. More alkali makes a faster bath that dies faster — Reilly’s warning is that an over-alkaline gold bath can hold plenty of gold and tone nothing, with no visible sign. Less makes a bath that stays yellow and inactive. It also has to dissolve, which is why the kit’s water is at 38 °C: borax is not very soluble cold. Its own page carries the classification and the handling.

Chloroauric acid, 8 mL of a 1 per cent solution, so about 0.157 g per litre. The gold, and the only substance that ends up in the print. The kit prints it as “gold chloride”, and the course’s reading of that name in the photographic literature is this substance rather than gold(III) chloride proper — the two are about 50 and 64.93 per cent gold, so a gram of the wrong solid is roughly thirty per cent more gold than the formula intended. Note the form of the quantity: 8 mL is not a quantity and 8 mL of a 1 per cent solution is, which is why the strength travels beside the volume here as it does in Kodak’s gold formulas. More gold tones faster and, past a point, deposits gold superficially so that the layer is largely removed in the fixer — Reilly’s warning, and precisely the failure this toner exists to prevent. Less tones slowly and eventually not at all; there is no published replenishment scheme for this bath, unlike the thiocyanate kit’s.

Water, 500 mL of it, distilled and at 38 °C. Distilled because a gold bath at 0.157 g/L is not a place to introduce whatever a tap supplies, and warm because the borax has to dissolve. The kit states no make-up volume, so the bath’s volume is not published and the strengths above are computed against the 508 mL of liquid it names and say so.

Interactions

With fixer, and the kit gives the rule in one sentence. The print need not be washed between the toning bath and the fixer, but be careful not to contaminate the toning bath with the fixer. Reilly’s version, on the chloroauric acid page, is that a gold toner is ruined by even a trace of fixer. Separate tongs.

With free silver nitrate on a freshly printed sheet. The intermediate wash exists for this. Silver left in the paper takes gold out of the bath before the image gets any, and the kit’s own criterion — wash in trays until one comes out clear — is how you know it has gone.

With over-washing, in the opposite direction. The kit warns that the image can be lost in that intermediate wash. It is a printed-out image with free silver around it and no gelatin to hold it down.

With acid, which takes the buffer out of its working range and is also everything Reilly’s yellow-bath test is about.

With metal. Ware records that these gold compounds are corrosive and oxidising, attack most metals and organic matter, and will stain skin a spectacular purple. Glass and plastic throughout, and the kit’s own container is glass.

With light and organic matter, both of which reduce dissolved gold — hence the brown glass.

With drying. The tone gets colder on drying; this is a property to plan around rather than a defect.

Variants

The gold-thiocyanate toner, the other supplier’s kit for the same papers: 50 mL each of a 2 per cent ammonium thiocyanate and a 0.2 per cent gold stock in a litre of water, at 0.091 g/L of gold, with a published replenishment scheme and a colour path that runs through red and maroon on its way to blue. See its page. Sulfur ligand against alkaline buffer, on the same processes.

Reilly’s Borax Bath, which is this formula’s own architecture at a very different strength: borax 10 g, 1 per cent gold chloride 40 mL, water to make 1 litre — 0.4 g of gold chloride per litre against the kit’s 0.157, and two and a half times its borax. The two are not in conflict; they are the same bath tuned to two different papers, and Reilly’s own strength rule says which is which. 0.4 to 0.5 g/L is his figure for glossy albumen; 0.1 to 0.2 g/L is his figure for matte salted papers, which are porous, tone quickly and would over-tone in the stronger bath. A supplier selling a salted paper kit at 0.157 g/L and a conservation handbook giving 0.4 g/L for albumen agree exactly, once you know which paper each is for.

Reilly’s sodium acetate toner, the other alkaline gold bath — fused sodium acetate 20 g and 40 to 50 mL of a 1 per cent gold stock to the litre, which generally needs twenty-four hours to ripen before it will tone anything. It has its own page, and its ripening time is the clearest illustration there is of what a mild alkali does to gold(III).

Kodak’s three silver-gelatin gold formulas — GP-1, T-21 and T-26 — all of which are the sulfur-ligand route and all of which are for developed-out papers.

The nineteenth-century borax baths themselves, which the Getty atlas names as the commonest toning recipes for collodion printing-out papers. The atlas gives no quantities, so they are recorded here as the ancestry of this formula and not as formulas.

No course variant is offered. The kit publishes two ingredients, a temperature, a time and a container, and there is nothing in that the course could change without changing what the formula is.

Safety

Level B, from borax and chloroauric acid, and their own pages carry the classifications, the exposure information and the first aid. Neither is restated here.

This is the mildest formula in the toner batch, and it is worth saying why in the same breath as saying it: there is no sulfide, no selenium, no thiourea, no persulfate, no ferricyanide and no acid in it. What is left is a borate buffer and a very dilute gold salt, worked at 21 °C.

The controls that matter, from the two chemical pages: nitrile gloves whenever the gold solid or its stock is handled — the aggregated classification gives severe skin burns and serious eye damage unanimously — splash goggles for the stock, plastic rather than metal for stirrers and trays, and hands washed before eating. Borax’s own page carries its classification, which is the reason it is at Level B rather than Level A, and it should be read before the powder is weighed.

The gold is weighed only if you are making your own stock. In the kit it arrives ready made, which is one fewer powder on the bench.

The fixer that follows is a separate formula with its own hazards, and the print is going into a tray of 100 g/L hypo immediately afterwards.

Storage

In a 500 mL brown glass container, which the kit specifies. Dark, because light reduces dissolved gold.

Away from organic matter, for the same reason.

No shelf life is published and none is invented here. What the sources give instead is a test: Reilly’s rule that a yellow gold bath is inactive and a working one is colourless, which is the best available statement of this bath’s condition at any moment.

Label it with the gold concentration, because a 1 per cent stock and a made-up 0.157 g/L bath look identical and one is worth six times the other.

Never in metal, including the closure.

Incompatibilities

Fixer, in the bath. The kit’s own warning.

Acids, which take the buffer out of range.

Metals, with the gold.

Light and organic matter, with the gold stock and the bath.

Sulfide and selenium toners, in the waste bottle.

Developer, in either direction, where one is in use at all — though on a printing-out process there is none.

Waste

A gold-bearing stream with a little silver in it, in small volume: half a litre of bath has had eighty milligrams of gold salt in it.

The much larger silver stream is the fixer and the first wash, not this. Open question 1.3 and the disposal ruling are about exactly that stream for the printing-out processes.

Not acidified, and not combined with any sulfide or selenium waste.

Collect it, label it, and follow the silver-bearing waste SOP, the general chemical waste SOP and the disposal ruling. Local regulation decides, and this course cannot tell you what it says where you are.

Troubleshooting

The bath is yellow and nothing is happening. Reilly’s test says a yellow gold bath is inactive: the alkali has not converted the gold. Check that the borax dissolved — 4 g will not go into cold water readily, which is why the kit warms it.

The bath is colourless and still nothing is happening. Reilly’s other failure: a bath made too alkaline tones faster and dies faster, and can end up holding plenty of gold while toning nothing at all, with no sign of it. Mix fresh.

The print lost density in the fixer. The toning did not go far enough, or the intermediate wash was skipped so the gold went to free silver rather than to the image.

The print lost density in the intermediate wash. Over-washed. The kit warns about this explicitly: change trays until the water comes out clear and stop.

The print came out colder than intended. Expected. The cold tone increases on fixing and on drying, so the print is pulled warmer than the result you want.

Uneven or mottled toning. The intermediate wash prepares the surface; a print that goes in unevenly tones unevenly.

The bath tones the first print well and the third badly. There is 80 mg of gold salt in the container and no published replenishment scheme for it. Mix a fresh bath, or use the thiocyanate kit, which does publish one.

Purple stains on your hands. The gold. Ware records the staining as characteristic; the gloves were the control.

Experiments

Plot the colour against time, on dry prints only. Identical sheets pulled at 2, 4, 6, 9 and 12 minutes, all fixed, washed and dried together. The kit says the result cannot be judged wet and that you will have to experiment; this is that experiment, done once, producing a set of reference prints you keep.

Compare the two routes. The same paper, half in this bath and half in the gold-thiocyanate toner, both at their published strengths and times. Sulfur ligand against alkaline buffer, one metal. The thiocyanate bath dissolves finely divided silver while it plates; this one does not, so the highlights are where the difference should appear first.

Watch the bath decolorise. Mix the formula and photograph the solution against a white card at intervals from mixing. Reilly’s test is that the yellow acid form is inactive and the colourless form is working; on this bath, with this alkali, that transition has a timescale nobody has published.

Vary the borax. The formula at 2, 4 and 8 g of borax, everything else held, each on an identical print. Reilly’s claim is that more alkali means faster toning and a shorter-lived bath; this is that claim as three prints and three bath lifetimes.

Measure what the gold saves. Two identical printed-out sheets, one toned and one not, both fixed for the same ten minutes and read for maximum density. Holding the image through the fixer is the formula’s first purpose and the easiest of its claims to quantify.