Print Buying Direct

Environmentally Aware Printing – Bio-degradability of inks – 27th January 2010

We are often asked the question, ‘Are your printing inks degradable’?

In order to answer it, we spoke to raw materials suppliers and commissioned a series of Scientifics tests on a cross-section of ink types.

The first thing to consider is the pigment in our inks. We know from discussions with leading pigment manufacturers that pigment is insoluble in water and practically non-biodegradable. As an ink can contain up to 25% pigment, this immediately tells us that no ink can be fully biodegradable.

In our scientific tests, we determined biochemical oxygen demand (BOD) figures to establish the potential for biodegradability in an aquatic environment.

The BOD5 figure is the percentage of material that is broken down by standard micro-organisms in five days. A value greater than 60% (as applied to detergents) is considered to indicate ‘readily’ bio gradable. The figures for our inks are, in most cases, well below this. (The figure for water-based ink may seem curiously low, but remember it contains a large proportion of water- and water is not biodegradable. The figure for 28 days exposure (BOD28%) is very different, with some much higher figures. This, we believe, is the result of ‘acclimatisation’, a process by which the micro-organisms adapt and mutate a strain suitable for activity.

It suggests that our ink systems are ‘inherently’ biodegrable, but we cannot claim that they are fully biodegradable.

The only synthetic resin that is ‘fully’ biodegradable is polyvinyl alcohol. Of the natural resins, shellac and unmodified rosin are possibilities. None of these makes a good film-forming material suitable for printing inks. With solvents, the choice is much wider.

But the only true benefit of biodegradability of a wet ink is in a surface litter or accidental spillage situation, neither of which would be a likely occurrence. As many inks are only suitable for disposal by incineration, biodegradability is not a factor. When inks are suitable for disposal in a landfill, bio-degradability is neither possible nor desirable. We do now believe that bio-degradable inks would make any significant contribution to solving environmental problems.

Effects of printing inks on water -borne species.
There is no evidence to suggest that printing inks affect water-borne species and micro-organisms. We commissioned tests on a cross-section of inks to assess any effects our inks might have – e.g. mutation, mortality – on micro-organisms in an aquatic environment.

Only one of the inks, water-based, was sufficiently soluble in water to give a test result. This figure was greater than 5000mg/litre which place it in the ‘neutral’ category. A water-based ink is unlikely to reach this level, even in the potentially more concentrated environment of a sewage treatment works. It is more likely to be a nuisance because of discolouration. However, no ink products, including water-based, are suitable for sewage disposal without special treatment.

For all the other inks, we can only look again at the individual raw materials we discussed earlier.

Pigments are insoluble and readily removed by sedimentation or absorption. The Ecological and Toxicological Association of Dyestuffs Manufacturing Industry (ETAD) has reported that all the indications are that pigments pose low risks and an overview of their ecological aspects is reassuring.

Information from suppliers shows that ink resins have a low potential to affect aquatic organisms, because of their low solubility and low biological activity.

For solvents, only the aromatic hydrocarbons have been indentified as potentially waster endangering.
Peter Harrison is Joint Managing Director of The Printing House Ltd,
and Print Buying Direct of Crewe, Cheshire, UK.

Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing.

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For more information on printing and graphic design please see some of our recent blog articles;

• Environmentally Aware Printing – Solvents
• Environmentally Aware Printing – Inks
• Environmentally Aware Printing – Recycled Paper – Reproduction
• Recycled Paper – Print appearance
• Recycled Paper – Printability

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and wide format colour printing. Based in Crewe, Cheshire, in the North West of England – delivering to customers across the UK and Ireland.

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