UV – Van Gogh’s enemy

• Science
• Lower Secondary (Key Stage 3)

Introduction

Masterminds & Masterpieces – an interactive lesson with an experiment to help students discover the influence of UV light on their own pictures, and also on the work of Vincent van Gogh. Students can carry out this lesson independently. Note: You need patience for this experiment (at least 2 weeks). (Age 12 <)

Instructions

General learning objectives

• Students find out what UV light is;

• Students learn about Vincent van Gogh;

• Students discover what the effects of UV light on paintings can be;

• Students come to understand why the effects of UV can differ according to colour and type of paint;

• Students investigate how to protect a painting from UV light;

• Students find out what UV does to their own work.

A curious, inquisitive attitude is required for the conservation and management of art and also for science and technology in general. This lesson is part of the Masterminds & Masterpieces series and makes use of the cross-curricular added value of inquiry-based learning (experimenting, trying out, looking, comparing, etc.). Masterminds & Masterpieces is a collaboration between the Van Gogh Museum and ASML.

Connection to the curriculum

- This lesson is connected to the subjects Physics and Science.

Materials required for the experiment

• 2 sheets of heavy-duty drawing paper

• a sheet of thick paper or card (size: 1/2 of your drawing paper)

• drawing pencil and felt-tip pens in at least 5 colours

• paper clips

• ruler

• sunscreen spray

• optional: writing paper or tablet

Variations

- This lesson can be taught in conjunction with the lesson UV – Van Gogh’s friend?

- The first part can be shortened by not asking the students to do a picture but instead to use a ruler and felt-tip pens to draw a number of lines in different colours on the paper.

- The various parts of the lesson can be used as separate assignments, spread out over a number of moments during the day or week.

the effects of ultraviolet light on the work of Vincent van Gogh

UV – 

Van Gogh’s enemy

What will you learn in this lesson?

During this lesson, you will discover and experience what UV light is and what its effects on paintings can be. You will also learn who Vincent van Gogh was. Then you’ll do an experiment. 

Conservator-restorer?

The conservator-restorer is a sort of doctor for paintings, who examines the condition of a painting. Is it damaged? Showing signs of age? Does it require treatment? The conservator-restorer takes care of the painting and protects it as much as possible from negative outside influences. Such as UV light.

She’s a conservator-restorer. She examines and takes care of works of art and old objects, repairing any damage.

One of the tasks of museums is to study their collections and to preserve them for the future. A conservator-restorer plays an important part in this work.

What kind of machine is this?

This is a microscope. You can use it to look at paint, very close up and strongly magnified. In this case, it’s the paint of Vincent van Gogh’s Sprig of Flowering Almond in a Glass.

What is this person’s job?

What is UV light?

Ultraviolet (also known as UV, ultraviolet radiation, or UV light) is a part of the sunlight that’s invisible to the human eye. As UV light has a shorter wavelength (between 100 and 400 nanometres) than visible light, it is more energetic. This means that excessive exposure to this radiation can be harmful to human beings, but also to people. UV radiation is invisible, but you can detect it with your skin. This is because UV makes your skin change colour.

Who was Vincent van Gogh?

- lived from 1853 to 1890;

- grew up in the Netherlands;

- lived in four countries (Netherlands, England, Belgium and France);

- decided to become an artist at the age of 27;

- made almost 900 paintings, lots of drawings and wrote hundreds of letters;

- wasn’t famous during his own lifetime;

- is now a very well-known artist. In 1990, someone paid 82.5 million dollars for one of his works.

Almond sprig

In the first two slides, you saw the conservator-restorer working on Vincent’s painting Sprig of Flowering Almond in a Glass. Vincent painted it when he had just moved to Arles, in the south of France.

On 2 March 1888, he wrote to his brother Theo: ‘There’s a hard frost here, and out in the country there’s still snow — I have a study of a whitened landscape with the town in the background. And then 2 little studies of a branch of an almond tree that’s already in flower despite everything.’

What effects does UV light have on Vincent’s work?

1. Colours become brighter
2. Ageing
3. Discoloration
4. Colours become deeper

Why does the conservator-restorer remove the layer of varnish?

1. Varnish burns into the paint under the influence of UV
2. Vincent didn’t like varnish
3. She didn’t have anything better to do
4. Old varnish was making the work look more yellow/brown

Paintings obviously don’t really ‘wilt’ like the one in the picture. Vincent knew that not all of his paints would keep their colour permanently and that his paintings might not remain exactly as they were when he painted them. He compared this to flowers fading. Those were his own words.

What causes these effects?

the composition of the paint

Paint is made up of individual pigments and binders. The pigments are the solid parts of the paint, and the binder is the liquid part, which also becomes solid after drying.

the discoloration of the pigments

Some pigments, but not all, change colour under the influence of UV light. This is a completely normal form of ageing. One pigment becomes darker, while another fades.

the discoloration of the painting

An artist may use quite a lot of different types of paint to create a painting. After lengthy exposure to light, the colours can change, but they don’t all change, and not all in the same way either. Some parts of the painting change colour more than others. Sometimes the paint hardly changes, if at all. It depends entirely on the composition of the paint and particularly on the pigments in it.

conclusion

UV light can make paint change colour over time. This depends on the composition of the paint: some pigments in the paint fade, while others become darker. This means that a colour can turn a different shade, as has happened in some of Vincent’s paintings. As you saw in the video, a conservator-restorer is trying to protect the painting from discoloration as much as possible.

Experiment: UV as an enemy?

Discover the effects of UV light on your picture.

What do you need?

• 3 sheets of heavy-duty drawing paper
• marker pens (at least 5 colours)
• an HB pencil
• a ruler (optional)
• paperclips
• sunscreen spray

Or you can use static transparent UV-resistant window film instead of sunscreen spray. This has the same effect on a painting as glass in a frame does. 

demonstration

Go to the next slide for a demonstration of the experiment.

Steps:

• Make two pencil drawings.
• Trace over the lines with marker pen or colour them in.
• Take a drawing and cover half of it with thick paper. Secure the paper with paperclips.
• Take the other drawing and cover half of it temporarily. Spray the other half with sunscreen.

1

• Attach the drawings, including the sheet of thick paper and sunscreen, to a window that gets plenty of sun.
• Wait for at least 2 weeks in the summer, and longer in the autumn, winter and spring. 

2

Wordweb

Use this wordweb to write down your questions and everything you noticed.

Weeks later... What did you notice? And what questions do you have?

Compare your results and Inssaf’s. Write down your conclusions.

Possible conclusions

Note: many effects and outcomes are possible.

The effects depend on:

- the strength of the sun

- the composition of the marker pens you used (some pigments change colour faster than others)

- the composition of the sunscreen

- the type of drawing paper

Now that you’ve finished this lesson, you know:

• what UV light is;
• who Vincent van Gogh was;
• what the effects of UV light on paintings can be;
• why the effects of UV can differ depending on colour and type of paint;
• how to protect a painting from UV light;
• what UV can do to your own drawings.