How to make art with coffee rings

Rather than coffee staining our teeth, or coffee table, let’s use this staining power creatively to make a ‘molecular’ work of art.

Hints and tips for coffee art

• Make sure that the coffee is very, very strong. We used approximately three times the amount of filter coffee needed for a standard cup and around a third of the amount of water – it needs to be very concentrated to colour the paper.
• To make a background like ours (to look like parchment paper) you can use tea or coffee. If using tea, soak the tea bag in cold water for a minute or two and then rub the soaked tea bag directly onto the paper (try not to get it too wet), before placing the tea-soaked paper into a preheated oven at about 80 °C until it is dry.
• Keep an eye on it because it will not take very long to dry. For coffee, brush a coat onto the paper and then put it into the oven at about 80 °C until it dries. Repeat if the colour is not as dark as you’d like.
• After the background is complete, ensure you draw dots to mark the places of atoms for your molecule. This is an important step because drawing the molecule freehand, without any guide marks, will most likely result in you running out of space.
• Using a thin paintbrush dipped in coffee, carefully trace out the shape of the molecule (once only). It is tempting to continue to go over it multiple times quickly to try and get a more defined figure, but it is important to allow the first coat to dry before you do the second, if you want a well-defined molecule.
• Putting more coats on top of a wet coat will just result in the coffee spreading to the surrounding paper and you will get a more abstract-looking molecule. For best results, put the paper back into the oven at about 80 °C between coats, allowing for a quick dry.
•  In total, your molecule will probably require six to seven coats to look well-defined and, using the oven method, you should have a perfect coffee-coloured compound in no time.
• If you’d like to burn the edges to make it look more ancient, you can use a match or a lighter, holding it to the edges of the paper and blowing out the flame once you have got the desired look. Do each little piece slowly, otherwise, you risk burning too much and losing some of your molecules.

While you are creating your masterpiece, you might like to reflect on some interesting articles about coffee.

Coffee can be good for you

A study has found that if the coffee beans have been highly roasted then the drink is less beneficial for your health. Concentrations of chlorogenic acid were found to be reduced on roasting and so the potential positive effects of this polyphenol (such as improving the function of the circulatory system and reducing the risk of developing high blood pressure) are diminished.

Also, in 2017, a large review of studies showed that moderate coffee drinking is safe, and 3-4 cups a day may have some health benefits.

This included finding a lower risk of liver disease and some cancers in coffee drinkers, and a lower risk of dying from stroke. However, the researchers could not prove it was due to coffee, so experts advise that you should not start drinking coffee for health reasons.

When is the best time to drink coffee?

Interestingly, the time at which we drink our coffee may alter its effect. If we consume coffee during times of peak cortisol (a hormone that is produced in our bodies to make us feel more awake and alert) production, research has shown that the effect of the caffeine will be greatly diminished and our bodies will build up a greater tolerance to the effects of caffeine.

For many people the optimal times for consuming caffeine appear to fall somewhere around 9.30-11.30 am and 1.30-5.00 pm.

Does coffee or tea stain teeth more?

Our tooth enamel is prone to staining as it contains microscopic pits and ridges that can hold particles of food and drink. Pigments from dark-coloured drinks such as coffee and tea can become embedded in the cracks and ridges causing yellowing staining of our teeth.

A dentist recently claimed that black tea can stain our teeth more than coffee. Many assume coffee has a greater staining power because it is darker in colour than tea, but looks can be deceptive.

The high levels of tannins (a family of compounds containing phenolic groups) in tea, including theaflavins and thearubigins, are believed to be responsible for the greater staining.

Tannins from plants, particularly oak bark, were once used in the process of tanning leather (they preserve the animal skin by binding to collagen proteins, making the skins stronger, stiffer, waterproof and resistant to bacterial attack).

Comparing the staining properties of coffee versus tea makes a really interesting science project!

Watching coffee dry

You may find this (microscopic) video of the coffee ring effect interesting – watch as spherical particles get swept to the edges.

Finally, add a drop of whiskey

On drying, drops of whiskey have been shown to produce unique patterns that might provide a tool for authorities investigating counterfeited products.

Research showed that when American whiskey was diluted with water down to about 20–30% alcohol content, on evaporation, the droplets began to leave web-like patterns on the glass.

The patterns arise because hydrophobic compounds within the whiskey aggregate when the water is added – each whiskey has its own flavour profile, made up of thousands of different compounds, including different hydrophobic compounds, so different brands gave unique motifs.