Planet Earth is blue (or is it) at Ground Control, Clerkenwell

Ground Control, outside the cafe

Ground Control on Amwell St

Ground Control is a small little cafe on Amwell St. If you are in the Angel/Clerkenwell area it is well worth stopping by this interesting cafe which serves a variety of Ethiopian coffees. Of course they offer the normal espresso, Americano etc. type drinks but if you want to sample their coffee properly, I think it best to try one of their coffees prepared with a V60. Tasting notes are shown on the menu on the wall. Being fairly small, there aren’t that many tables, however if you are lucky enough to get one of the two tables at the window, you will find plenty around you to look at without resorting to checking your phone while you enjoy your coffee. Behind one of the tables at the window is a set of shelves with coffee beans (presumably for sale). Behind the other table is a picture of a lady holding a jug and a basket. Vibrantly coloured circular patterns form the backdrop behind her.

coffee mosaic, colour perception

The coffee mosaic at Ground Control

The picture (shown on the left) has a flow to it, you are almost drawn into the movement of the picture. This movement comes from the many, differently coloured, coffee beans that have been used to make the picture. Each bean is orientated slightly differently so that the lines through the bean flow with the picture, rather than the beans being mere individual pieces of a mosaic. The circular patterns, the lines of her shirt, all of these are produced by orientating coffee beans this way or that. The mosaic is also richly colourful. Many of the colours stand out, but some, arranged next to each other, appear more subdued. How do we see the colours of a picture? How much of our colour perception is due to the pigment of the paint, how much due to the lighting, and how much is due to the individual colouration of the neighbouring beans?

An artist known for his unusual use of colour was Georges Seurat (1859-1891). Seurat developed the technique of pointillism in which small dots of varying colours are painted next to each other. Viewed from a distance, the colour seen by the viewer may be quite different from the multitude of differently coloured dots perceived close up. As with the coffee bean mosaic, direction was given to Seurat’s work through the orientation of the painted dots. Seurat had based his technique on the state-of-the-art science of the day. One of the scientists whose work on colour theory influenced Seurat’s artistic development was Ogden N. Rood, a physicist who’s 1879 book “Modern Chromatics” he seems to have read (in its French translation)*. Rood had carefully distinguished between two types of colour mixing, that of mixing coloured lights and that of mixing pigments. Mixing pigments had been used by all of the old masters. It is the process by which paints are mixed to produce a new paint colour. Rood however showed that if small dots of colour were painted adjacently, when the painting is viewed from a distance such that the eye cannot distinguish the two dots individually but rather mixes them in the eye, the colour produced is that of mixing coloured lights, not coloured pigments. As he explained, colour mixing through adding light of different colours was an additive process, colour mixing through combining pigments was subtractive. More about colour theory and colour mixing can be found here.

Pointillism Seurat

Georges Seurat, 1859 – 1891
The Channel of Gravelines, Grand Fort-Philippe
1890, Oil on canvas, 65 x 81 cm, Bought with the aid of a grant from the Heritage Lottery Fund, 1995, NG6554

In the late 1880s, Seurat was criticised for relying “unduly on scientific formulae”, though he himself seems to  have viewed his use of science merely as a guide, a way to help control the colour and light seen by the viewer*. The colours that we perceive can be affected by the colours they are adjacent to, as evidenced by many optical illusions. Yet even when everybody is looking at the same photo, we do not necessarily all see the same colour (I saw it as white and gold).

There is indeed a lot to the science of colour perception and some great fun that can be had with it. Seurat was aware of some of this and used science to understand how to best paint his paintings. Note how the (pointillist) border of the Seurat painting pictured on the right is a different colour at the top, do you think that affects how your eye perceives the top compared to the bottom of this painting?

Starting tomorrow, light and colour are to be combined in a three day “Lumiere festival” across London. The event looks as if it will take full advantage of the effects of different methods of colour mixing. If you are outside London, sorry! If you are lucky enough to be in London over the weekend, more details of what looks to be a fascinating science/art/experience event can be found here.


Ground Control is at 61 Amwell Street, EC1R 1UR

*”Seurat and the Science of Painting” by William Innes Homer was published by MIT press in 1964

Ordinarily I would have left the title of this post as a type of puzzle to see if anyone got the link (some posts on the Daily Grind have such puzzles, I’ve no idea whether I’m the only one who understands some of them). However, given that he passed away two days ago, here’s a rendition of David Bowie’s Space Odyssey (which is referenced in the title) sung by Cdr Chris Hadfield:


Diamonds are forever at Violet, Hackney

the outside of Violet

Violet in Hackney

Violet is not quite where I expected it to be. I had expected it to be in a row of shops on a main street, instead it is tucked away, a little cafe in a back street in Hackney. Despite the relative anonymity, Violet has won awards for the quality of its cakes. Award winning cakes are hard to resist and so, a few weeks ago I went along to Violet to try the coffee. With a couple of seats outside and a large room upstairs with seating, it is very easy to enjoy a good coffee and a cake while taking in the surroundings. The cakes certainly do not disappoint and, importantly for Bean Thinking, they know exactly what goes in them, meaning that if you are allergic to nuts or have other food allergies or intolerances, they are incredibly helpful. They definitely get a tick in the “cafe with good nut knowledge” category.

As it had been raining when we tried Violet, we decided to take a seat upstairs. Stacked in one corner of the room were a set of wooden chairs, reminiscent of those chairs that we had to stack at school. Each chair fitted almost exactly onto the previous one. At the top of the stack of chairs however, the uppermost chair did not fit exactly onto the previous chair, it was as if there was a defect in the stack.

stack of chairs, Violet

The chair stack in Violet.

The diagonal legs of the chairs resembled the multiple strata in a layered substance such as graphite. Each layer of graphite features a hexagonal arrangement of carbon atoms forming a structure very much like the chair legs in the chair stack. Graphene, a material of which there is currently a lot of hype, is a single layer of graphite. The carbon equivalent of one chair leg on its own. Carbon is a fascinating element. If, rather than being arranged in layers, it is arranged into a more 3D crystal structure, then you get diamond, a colourless, extremely hard crystal structure, very different from graphite. It is in diamond that defects in the stacking structure (such as with the uppermost chair) can cause spectacular effects.

If the carbon atoms are arranged into a perfect crystal structure, (the equivalent to the chairs being perfectly stacked), then diamond is colourless. If on the other hand, something happens to disrupt the structure, perhaps there is one carbon atom missing in the structure or maybe another, impurity element, such as nitrogen, has got in, the way that the electrons in the diamond react to light changes. This means that it can take on a colour. The introduction of nitrogen for example, in concentrations of only 0.1% will make the diamonds more yellow or orange. Red diamonds are a consequence not of impurities but simply defects in the crystal arrangement. The equivalent to that one last chair in the chair stack changing the properties of the stack completely. Knowing that the colour of a diamond is a result of a defect in the arrangement of carbon atoms in the structure offers us two possible viewpoints. Either people who buy red diamonds are paying a premium for defective goods, or, beauty takes many forms and what is beautiful is not necessarily what is regular and perfect. I know which view of the world I prefer to take.

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Violet is at 47 Wilton Way, E8 3ED