Growing Your Own Ink - Conclusions and Printing

Growing Your Own Ink
by Phil Shaw MA(RCA)

Conclusions

So what are my initial conclusions after eight or nine months of testing? Well, of the ninety or more species tested so far, 15 domestic plants and 5 tropical and sub-tropical plants have released significant amounts of colour. This is not to say that the others produced nothing. Many tree and shrub clippings produced (sometimes with monotonous regularity) a variety of browns, due almost certainly to the large amounts of tannin which they contain, and these are often good sources of black when combined with Ferrous sulphate (Fe).

Fig. I. Spectral reflectance curve of standard process cyan shown in bold, compared with the reflectance curve of an indigo print sample, indicated by the shaded line. In the standard sample the peak around 470 nm. is that area of the spectrum responsible for blue/green, or cyan reflectance. It can be readily seen that the indigo sample has only a very modest peak in that area, along with a pronounced peak around 700 nm. the area responsible for red reflectance. In simple terms, we can determine from this that the colour being represented is a fairly dull blue, which also contains a touch of red - in other words indigo.

Fig. 2. Spectral reflectance curve of standard process magenta shown in bold, compared with the reflectance curve of an elderberry/mahonia ink sample indicated by the shaded line. Whilst the two samples show similar reflectance at the red end of the spectrum (650-700 nm.), they differ considerably in the violet, blue, green and yellow (400 nm - 600 nm.). There is however a general similarity in the overall peaks and troughs, demonstrating that this particular combination may be capable of adjustment.

Fig. 3 Spectral reflectance curve of standard process yellow shown in bold, compared with the reflectance curve of a Persian berry (buckthorn) ink sample, indicated by the shaded line. As with Fig.2 the vegetable ink sample conforms in general terms to the standard sample, though there is too much reflectance in the blue (430-500 nm ) and not enough reflectance in the green (510-550 nm). Once again this suggests that adjustments could be made that would bring the vegetable ink sample more in line with the standard. More recent tests with weld have demonstrated, at least to the naked eye, a greater degree of conformity with standard process yellow, though spectrographic tests have not yet been applied.

Tests Courtesy of Davison Chernographics Ltd

Of those domestic plants which produced positive results, I should say that at least nine or ten would be worth cultivating as realistic alternatives to traditional colour sources. In fact it should be possible, in my opinion, to obtain a complete range of colour from as few as three or four different species; Elder (Sambucus nigra ), Mahonia (Mahonia aquifolium, and other varieties), Selenium (Selenium intrusum/scabrum) and Buckthorn (Rhamnus sp.) for example.

These four plants have the added advantage of being shrubs and will, with the exception of Selenium (which should be regarded as a half-hardy sub-shrub), go on cropping year after year with minimum of attention. Beetroot, red cabbage and red onions also provide strong colourants. In the case of red cabbage I got an almost perfect magenta for colour separation work, but unfortunately it was rather fugitive, fading considerably within two weeks in direct sunlight. This problem however, may not be insurmountable, for after talking to a couple of organic chemists, it seems that there may be a number of additives that might fix the colour more permanently and this will be one of the problems I shall be addressing in future research.

Of those species which can only be grown in warmer climes, brazilwood (Caesalpina sappan, C. crispa and C. echinata) and turmeric (Curcuma longa) leap to mind immediately. Both of these provide brilliant hues and it is a pity that brazilwood simply cannot be grown without hothouse conditions, though turmeric is so cheap to buy in powdered form, particularly in Asian stores, that I would be tempted to class it as a domestic species, certainly from the point of view of availability. Turmeric is probably the cheapest yellow pigment of any kind that is currently available!

Printing

As I have already stated, one of my aims was to produce a range of process colours and this has been the main focus of my attention, though of course, the process of testing has revealed a great number of other usable colours.

In March 1995 I was at the stage where I certainly had a potential magenta in elderberry or mahonia, a definite blue (cyan) in solanum and I would use turmeric for the yellow. However, I’d invested so much time and effort into the research that I was too nervous to grasp the nettle and see if it worked! In fact I needn’t have worried, the first print test though not a resounding success, did surprise me very much, for there in front of me in the racks, was an (almost) full colour reproduction of a photograph I took at a Crystal Palace ‘Fruit and veg’ stall. The blue, partly because I had such a small sample to work with, was over-extended, the magenta (from elderberry) was close if not perfect and the yellow quite adequate (I used 65 lpi separations on a 90 tpi screen). Figures 1, 2 and 3 demonstrate the not inconsiderable differences between the vegetable samples and standard process colours, but they are close enough to suggest that with chemical modification these discrepancies could be minimised.

Phil Shaw MA(RCA)
Associate Lecturer
Middlesex University
Faculty of Art Design and Performing Arts
Cat Hill
Barnet
Herts EN4 8HT
England
E mail Phil 9@MDX.AC.UK
Tel 0181 362 5059/5070

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