Bromoil and oil pigment printing

Writer / Terry King

A description of the process.

Always be careful when handling chemicals. Read the health and safety instructions.

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Image right: The End of Maerdy Colliery South Wales – bromoil

Bromoil was developed in the early years of the century to enable ‘control’ to be exercised over straight black and white silver prints. It superseded oil prints which worked on the same principle but required a contact negative. Both the bromoil, (bromide plus oil), and the oil pigment print depend on the lithographic principle that wet rejects oil and dry accepts it. If the gelatine in a photographic print is treated so that the shadows are tanned, that is made less able to swell when soaked in water, then the shadows will accept oil based inks and the highlights, replete with water will reject them.

Pigment Print

An oil pigment print is produced by coating water-colour paper with three layers of gelatine, I use photographic gelatine of about 260 Bloom) first a 5% solution and then on drying, first one and then another 7% solution. There are many different ways to achieve good results. I use two different methods of coating. The first is to make up a tray of the gelatine at the appropriate dilution. The gelatine must be kept at above the melting point of gelatine, about 104 F or 40 C. The paper, I use a 300 gsm watercolour paper, is immersed in the gelatine for three minutes for each coat. Agitate the gelatine bath to avoid the development of bubbles. As you remove the paper from the tray wipe the paper across the edge to remove any last hint of bubbles. Hang the paper up to dry in a flow of warm air. Repeat for each coat.

Alternatively coat the paper with a hake brush but make sure that the gelatine is above the melting point of gelatine and flows well. Repeat for each coat. There may be an advantage in adding a very small amount of chrome alum to the 5% coat but not subsequent coats. The alum helps the 5 % coat to bond with the paper. The amount used should be very small; in old terms a one grain solution, that is one grain to a fluid ounce or.05 g in 30 ml, which can be added to a litre of the warm gelatine. When this has been sensitised using a 2% solution of ammonium dichromate in water,or a 3% solution of potassium dichromate, at 17C , allowed to dry in the dark and exposed under a negative, and then washed for an hour, finishing with warm water (under 38C), the resulting gelatine matrix will be ready to receive ink in the same way as the bromoil matrix the recipe for which follows.

Image right: Bromoil prepared with sponge decorators’ roller

1Use either B&W printing paper with no super-coating, (there are rare boxes of Kentmere Document Art still around) or or a super-coated paper where the method is different. If you are using non super-coated paper make a slightly overexposed print such that the highlights are slightly veiled. Avoid large areas of very dark tone. With supercoated papers it is best to make a very dark print, e.g.

This print is on the Hungarian paper Foma which I prefer; Ilford gallery and Multigrade Warm Tone both work well.

2Develop the non supercoated paper using a developer containing no caustic soda, eg Ilford PQ Universal develop the supercoated paper in an amidol developer:
sodium sulphite 14 g
potassium bromide 0.5 g
water 568 ml
scatter 4.5 g of amidol over the surface of this solution in the tray and agitate until dissolved.

3Rinse.

4Fix in a 10% solution of plain hypo for 10mins.

5Wash for three hours.

6Blot off until no dampness shows.

7Dry in warm until crackly.

8Soak in cold water for five minutes.

10Wash for 10 minutes.

11Fix in 10% hypo for 10mins. If you do not fix at this stage your silver picture will reappear!

12Wash in running water for thirty mins.

13Soak in warm water (30 C for non super-coated paper and 40 C for super-coated papers, allow the water to cool during the soak) at the start for twenty mins. or until relief image shows.

14Swab to remove scum.

15Dry.

16Resoak at room temperature until relief shows.

17Blot until there is no sign of surface dampness.

Image right: Downs – bromoil

From this point the processing of the bromoil and the oil pigment print are the same:

 

18Spread a little oil based litho ink on a piece of glass and with light dabbing motions of the brush transfer ink to another part of the glass; work from the transferred area.

19Ink up, using a Boots imitation badger shaving brush*, with a dabbing motion and very little oil based lithographic ink, only on the very tips of the hairs of the brush, until the whole image is covered (better results can be obtained with genuine bromoil brushes with a stags foot shape and fairly soft hair; modern bromoil brushes that I have used proved a little too hard ). Highlights need softer ink achieved by adding a drop of plate oil (boiled linseed oil) to the ink before it is spread on the palette. One can even use a spotting brush for the highlights if the ink is of the right consistency. Ink for the shadows can be stiffened by adding a tiny amount of light magnesium carbonate.
* The student who used her husband’s amber handled genuine badger hair shaving brush was not seen again.

20After you have obtained an overall grey tone. Stop adding ink to the brush and then use an oblique light stabbing and twisting movement which has the effcct of reducing the ink from the highlights and transferring it to the shadows thus increasing contrast. It will be seen that the darker the overall grey tone before you start the hopping action, the darker and contrastier your print will appear.

21With super-coated paper as you work the print may dry of before you have reached the depth of tone you need. If so, re-soak and dry off with lintless blotting paper or cotton wool until no dampness shows and then continue with the inking process. With super-coated papers it may help to abrade the surface of the paper slightly. A very effective way of doing so is to ink up until you have achieved an image then soak the paper, remove all the ink and then start the inking process again.

22A smoother effect can be obtained by inking up using a foam sponge decorators’ roller or a brayer which needs to be of very high quality preferably made of hardened gelatine A decorators roller costs pennies while a quality brayert costs hundreds of pounds.

23Leave the print for some days to harden. After the print has hardened it is easy to introduce local colour with oil pastels using small shavings rubbed in with the finger to obtain delicate shading.

24Alternatively run the print face down onto soaked printing paper, between a sandwich of lintless blotting paper, through an etching press. This will give a bromoil transfer. Re-ink and repeat for an edition of up to twelve prints There is no guaranteed method of removing ink. For example very delicate manipulations can be achieved by working with the work piece under the surface of the water. Synthetic bath sponges can prove very effective, The tool for blotting can be lintless blotting paper from art print suppliers or cotton wool from the pharmacy but be careful to avoid leaving strands on the print. The light magnesium carbonate is sold at pharmacies as some use it as a foot powder for sweaty feet. Plate oil is also available from art printing retailers who are, of course, the source for lithographic inks in a wide range of colours. There are many different methods which can be adjusted to suit one’s working methods or personality. It is worth adding that over the years a pattern has emerged that accountants are usually good at oil prints and bromoils. This observation arises from a very small sample and is almost certainly not statistically significant.

There is no guaranteed method of removing the ink. For example very delicate manipulations can be achieved by working with the work piece under the surface of the water. Synthetic bath sponges can prove very effective,

The “tool” for blotting can be lintless blotting paper from art print suppliers or cotton wool from the pharmacy but be careful to avoid leaving strands on the print. The light magnesium carbonate is sold at pharmacies as some use it as a foot powder for sweaty feet. Plate oil is also available from art printing retailers who are, of course, the source for lithographic inks in a wide range of colours.

Image right: The Old Ghetto, Venice – bromoil

There are many different methods which can be adjusted to suit one’s working methods or personality. It is worth adding that over the years a pattern has emerged that accountants are usually good at oil prints and bromoils. This observation arises from a very small sample and is almost certainly not statistically significant.