Plant based colours

The Painting Plants organisation is targeted towards creating paints, dyes or ink from plants to be used in different printing techniques. Researchers and artists of Painting Plants are cultivating different species of dye plants for colour research to make ink to apply in different printing techniques. Therefor they asked the WUR Science Shop and students to advise them on how to improve their method of harvesting, preparation of the plants and treatment for the production of colours. In order to gain understanding of the plants behaviour and it's colour manifestation.

Painting Plants is a small company that is interested in the use of natural colour pigments for the art and textile industry. Painting Plants would like to contribute to a more environmentally friendly way of producing natural compounds. It is known that the methods, time of harvesting and surroundings have influence on the quality and applicability of the colour.

Even though Painting Plants is growing many different kinds of plants, the methods to extract pigments and the pigment yield obtained by that methods are not sufficient to produce commercial products. Therefore, the ACT team explored the results and feasibility of using other solvents than water for upscaling and product development of paint for arts. In addition, instead of focusing on ways to upscale the plant production the consultancy team has looked into using waste products to increase the production of natural pigments. For this, the team has looked for sources that can provide the pigment-containing material such in bulk. Examples of such materials are flowers being leftover from the auctions, orange peels and shells of pressed fruits such as berries. The availability of such material and the possibilities of pigment extraction are explored.

The best growing conditions and the phytochemistry of the dyeing compounds of a list of plants requested for by the commissioner are described.

The students also explored the possibilities to use waste as a source to produce paint from natural pigments. Many companies were contacted that might be able to provide the students and later Painting Plants with plant waste to use for natural pigment extractions. Plant material from roses, coffee, avocados, elderberries, beetroot, carrot and sweet potato was collected. Extractions were performed based on protocols made by collecting information from the available scientific literature. The aim of the experiments was to evaluate if it is feasible to use specific food waste sources to produce paint on a large scale, taking into consideration the yield, cost, colour appearance and stability.

The results of the experiments showed that food and floral waste material can be utilized effectively for paint production. Above all waste materials used, elderberries showed the biggest promise. This source indeed produced the highest yield with the extraction methods used in the experiments, whereas carotenoid extraction proved to be the most difficult.
The biggest bottleneck is probably the lack of stability of such natural pigments. Based on the experiments the ACT team performed, however, no statements about the stability of the produced pigments can be made. Time restrictions of the project forced the omission of the stability tests, that need more time and long-term controls. As the biggest drawback of natural pigments compared to synthetic ones is indeed the lack of stability, it is highly recommended to assess the stability of the various pigment/binder combinations used in time. For this reason, the charts on which paint was tested will be handed over to the commissioners for them to perform check-ups over time.