The renovation of the palm tree at de Gaulle roundabout

The Palm at de Gaulle roundabout – an installation by artist Joanna Rajkowska – was officially unveiled in December 2002. Over the past two decades, it has become a significant and iconic landmark on Warsaw's map. Due to the challenging conditions it operates in, it has become essential to replace the existing leaves with new ones. In autumn 2023, the Museum of Modern Art entrusted this task to the Faculty of Materials Science and Engineering.

The challenge was taken on by Rafał Kozera, PhD (ENG), and Kamila Sałasińska, PhD (ENG), along with their team. Initially, it seemed like a project that would be simply interesting and enjoyable. However, it soon became apparent that it was far more complex, requiring attention to numerous details and the resolution of many issues at each stage of production. Ensuring that the process was carried out with meticulous care and completed within the set timeframe became essential.

The documentation of the work on the palm, created sporadically over more than 20 years, was incomplete, and access to the installation – due to, among other reasons, formal restrictions – was highly limited. Therefore, recreating the original process and the leaves was out of the question.

Work without a handbook

Interestingly, the first concern at the outset turned out to be selecting the right color for the leaves.

– Ms. Joanna Rajkowska was given a palette of 10 or 12 shades of green – these were mixtures of different colored pigments in varying proportions – says Rafał Kozera, PhD (ENG).

After a series of tests and discussions, once a satisfactory result was finally achieved, the next step was to focus on the material.

– There is no manual for designing a palm or its leaves – says Rafał Kozera, PhD (ENG). – It had to look and move naturally in the wind. We needed to determine the properties the leaves should have – balancing stiffness with the required strength to ensure resistance to harsh weather conditions, and flexibility to achieve a natural 'swaying' effect in the wind.

This required strength tests, aging tests, and computer simulations. Ultimately, glass fabrics and a polyurethane matrix were used for the production of the leaves. In addition, the central polymer layer was designed to strengthen the entire structure. Composite molds were also created – designed by the WUT team and specially manufactured for the project by ROMA. These molds had to take into account not only the material used and the specifics of its processing but also the fact that the leaves have stems, which are made from steel rods. The use of computer simulations became indispensable to ensure the palm’s natural appearance. Over the course of the project, as new challenges emerged, the design was revised several times. All of this required testing and time – in total, around 20 prototype leaves were created.

The entire technological process was developed by a team from the Faculty of Materials Science and Engineering at Warsaw University of Technology in close collaboration with the company Lubas, which provided access to its machinery and additionally involved its specialists. Throughout the process, the consultant was, of course, the author of the installation, Joanna Rajkowska, with support from the Museum of Modern Art.

Leaf production

The palm consists of 74 leaves, each measuring about 3–3.5 meters and weighing approximately 15 kg. Not all of them are the same – there are four different leaf lengths, each suspended in a precisely defined position.

– Producing the leaves alone took us over 650 man-hours – says Dr. Rafał Kozera, PhD (ENG). – For each one, 6–8 people worked on it. Once we saw that it was working, it became a real pleasure to produce the next leaves.

Cutting one leaf took about an hour. This was done using a water jet cutting machine. After cutting, the edges had to be secured – the total length of the cutting line was over 100 meters.

The project involved 10 people from the Faculty of Materials Science and Engineering at WUT, including students and doctoral students.

– Each person who was involved in the project contributed something to the process – whether by improving it or proposing a fresh idea to solve a problem – emphasizes Rafał Kozera, PhD (ENG). –Everyone played their part.

Their palm tree

– Everyone involved in the project was eager to see the final result and witness the palm tree in its full glory – admits Rafał Kozera, PhD (ENG). – The final effect exceeded our expectations, only increasing the satisfaction and pride we feel for being part of this endeavor.

– It was a unique experience – adds Rafał Kozera, PhD (ENG). – Everyone knows where the palm is, so we were aware that we were creating something that would be visible and commented on. It will always be our palm.

Are our researchers ready for more projects like this?

– We have a flexible, easily moldable material, and the color can be changed – points out Rafał Kozera, PhD (ENG). – Polyurethanes are widely used in industry... Why not?