We know that plaster has been used since Egyptian times. We use it to repair broken limbs and decorate buildings, and a whole range of specialised skills like plastering ─ sometimes with stucco or staff ─ and pattern (mould) making revolve around this age-old material. So what exactly is staff? Basically fibrous plaster: in other words plaster that has been reinforced with hemp, jute or coarse cloth. It is used in architectural embellishments like capitals for column tops, acanthus leaves, cornices and rosettes. Moulding these ornamental pieces and then fitting them on to walls and ceilings is challenging work.
 
3 questions for Mr Peyssou, specialised fibrous plasterer with the company Soe Stuc et Staff:
 
What did your work in restoring the rotunda at the Grand Palais involve?
When you work with staff there are different options, and we chose moulding. Based on the original drawings, we made our own full-scale drawings of the ornamentation, and after these had been approved by Alain-Charles Perrot, the chief engineer responsible for historic monuments, we made scale models in clay. We used these to make the elastomer (synthetic rubber) moulds in which we cast the plaster. When they come out of the workshop, they have to be fitted into place. To facilitate adhesion to the ceiling we fasten wadding (fabrics dipped in plaster) to them.
 
How do you get into the trade?
I come from a family of plasterers that goes back generations. I learned my trade from the Compagnons du devoir, a craftsmen's organisation that goes back to the Middle Ages. I learned the basic plasterer's skills and went on to master staff and stucco after I joined Soe, Stuc et Staff. These skills all form a whole: when you know them all you can pick the best technique for each job.
 
What does it mean to you to be working for the Grand Palais?
It's a grandiose project with a lot of prestige, on a completely different scale from what we usually do in private homes. It was like entering the skin of the workers at the end of the 19th century who never got to do the job themselves because of the deadlines. It's a once-in-a-lifetime experience!
 

The art of mosaic is almost as old as civilisation itself. We know that it existed in Mesopotamia and then in Greece in the third century BC and was considered as "painting for eternity". At the time, mosaics were set directly in place using a form of plaster bond. There was no room for mistakes and mosaic workers were among the most skilled craftsmen. Since then techniques have changed. Richard Boyer, manager of the Paris branch of the company Socra, which restored the mosaic floors of the loggia in the Grand Palais on avenue Winston-Churchill told us more.
 
Why did the mosaics in the loggia need restoring?
Originally, the floors in the loggias were paved with marble mosaics, but these were modified in the 1960s to make way for glass tiles intended to allow light into the rooms below. When these glass pieces were removed to reproduce the original layout, it became clear that some mosaic was missing and some had been damaged. Half of our work consisted of replacing the missing tesserae and the other half of restoring what had been damaged.
 
So what exactly is a mosaic?
Generally it s a figurative or geometrical decoration made from small cubes assembled together. These tesserae can be made from different materials: glass, marble, ceramics, or terracotta. The tesserae in the loggia were made from limestone or marble.
 
How many tesserae did you use?
Given that it takes over 6,000 tesserae to cover one square meter, and that the area of the loggia is around 126 m2, we used some 756,000 tesserae! The whole job took nearly six months.
 
How do you organise the work?
The first step was to take samples of the materials and colours used in the loggia. We used them to select and order the marble we would use.
We then made a tracing of the existing decoration or significant motifs.
For the missing areas, we copied the models using the indirect method invented in the 19th century by Gian-Domenico Facchina, a mosaic restorer. Instead of setting the tesserae cubes directly on the floor in situ, you apply them, hand-cut with a martellino (a small mosaic hammer) or pincers, face-down on to a flexible medium like brown paper or polyester film.
 
So far this was all done in the workshop?
Yes, it was much more practical. Similarly, we assembled the mosaic in panels to make them easier to handle. It was only afterwards that we returned to the Grand Palais to fix the panels to the floor using fresh mortar. With the effect of the humidity the backing medium peeled off. We then joined the old and new parts together using a grout between the cubes, and sanded the new panel lightly to soften the texture of the marble and make it look more like the original.
To restore the existing marble, we injected a lime-based grout to fill cracks below the surface. Where it had become too badly detached, we removed the mosaic to work on the base before setting it in place again.
 
The reverse technique was only invented in the 19th century?
Yes. The art of mosaics, very popular in Ancient Greece and Rome, had gone out of fashion. It found favour again in the 19th century. It became clear that Gian-Domenico Facchina's reverse technique cut costs tenfold and produced a far sharper end result. His last big project was the Paris Opera House in 1867. After that, mosaic art really took off again and became massively popular.
 
How did you get into the trade?
I was always and attracted by art and, at the age of twelve became really interested in archaeological digs! I studied history of art and specialised in archaeometry (scientific methods for the study of archaeological materials) at Bordeaux University.
I joined the company Socra in 2000 to learn about restoring. The company was founded in the 1960s and has a workshop in Périgord, in the Dordogne, devoted to the restoration of décors, stone and metal sculptures, medieval tiles and of course mosaics. Today I'm in charge of the Paris branch, which employs several restorers, and more specifically with technical studies, quotations and monitoring restoration projects.
 
What does it mean to you to be working for the Grand Palais?
It's fascinating, especially since this is not the first restoration job we have done for the building. We did Recipon's Quadrigas in 2003, the mosaics for the upper part of the loggia, the stoneware mosaics that decorate the walls on avenue Franklin-Roosevelt, and the bronze statues in front of the palais de la Découverte facade. It's become a kind of second home to us!

The Jehanno family have been working with wood for the last four generations. After studying at the Ecole supérieure du bois in Nantes, Olivier Jehanno is today the engineer in charge of construction joinery projects commissioned by the Charpentiers de Paris. He executed the new woodwork for the Queen's Rotunda.
 
What did your work for the Grand Palais involve?
We made the five wooden structures used in the Queen's Rotunda. These are large folding and double-leaf doors. The wood used is French oak. Every historic building has its own joinery "profile". In the Grand Palais this is characterised by the style of the mouldings, notably those on the large wooden panel in the lower part of the door. We base our joinery work on the architects' plans and on the existing woodwork. We take measurements, trace back the original mouldings, and study the profiles; in short, we take the time to study the work of our predecessors. We then go to our design office and make our drawings. What is really interesting is to analyse the existing woodwork, see the different assembly techniques used, research the production methods and find a design that is similar to the way the craftsmen worked at the time.
 
How long did the work take and how many people were involved?
The project required three months at a workshop in Bagneux near Paris, and a further two months to fit it all into place. In all, fifteen people worked on the project: me, two draughtsmen, ten skilled workers for the production and four for the fitting on site. My jobs are to coordinate the design office, interface between the main contractor and the architect-in-chief for historic monuments, and make sure that everything is going smoothly in the workshop.
 
What does it feel like to be working for the Grand Palais?
I really like buildings that carry so much prestige. To work on sites like this, you have to take an interest in their history, and acquire an in-depth knowledge of the heritage. It's a fascinating experience on both the professional and cultural levels. It's the first time that I've worked at the Grand Palais and I must confess that I do take a certain amount of pride in being involved!

Quadriges talked to Madame Thomas, quantity surveyor and project manager at Trouvé, a specialised painting and decorating firm
 
What did your work at the Grand Palais consist off?
Our company did the white, ivory and mignonette green paintwork on the staff caissons in the rotunda and the south-east gallery.
 
What stages did the work involve?
We began by doing some research into the paint originally used at the end of the nineteenth century. By scraping off samples of the paint and taking them to the laboratory for analysis we were able to work out the formulae used at the time. We then went to the factory and made paint specially for the Grand Palais. This we applied with rollers before finishing the job with a patina using cloth and sponge.
 
Why did you add the patina?
It brings a light, decorative transparent effect that is pleasing to the eye.
 
What about the stats? How many pots of paint did you use and how many people worked on the job?
For the 800 m2 (8,600 sq. ft.) of the south-east gallery and the 200 m2 (2,150 sq. ft.) of each rotunda, we used around one hundred pots of paint and had five people working on site.
 
What exactly does your job as quantity surveyor involve?
I do the initial study for the project, cost it and then supervise the whole operation: organizing the work on site, scheduling, etc. I joined Trouvé in 1987 after leaving school with a professional baccalauréat diploma in finishing, interior decoration and layout. Almost all house painters are trained as decorators. The rest you gain from experience as you go along.
 
6/ How did it feel to be working for the Grand Palais?
It's a source of pride to be revitalising the work of our predecessors, and contributing to safeguarding our heritage. For the last 22 years I've been working exclusively on historic buildings: theatres like the Odéon, the Comédie-Française, and the Gaité-lyrique, and the Louvre Museum… You feel good in places like this. You really want to put something into it. More than elsewhere.

Since the end of January, Boullet, a company specialised in fire safety, has been working on the glazed firebreak floors in the rotunda. Marketing director Cyrille Schroers talked to us about the project.

What has your work consisted of?
At the centre of the mezzanine floor in each rotunda is a glazed oculus with a diameter of 3 meters. We have been bringing this into line with fire safety standards that required 90-minute retarding capability. Above this glazed firebreak complex, we are installing glass slabs on which visitors will be able to walk. This is why we guarantee that the floor will be able to bear an excess load of 500 kg/m2.

What makes the work so special?
This is delicate work that means reconciling technical constraints with respect for the original style of the building. The new glass slabs we have made for the rotundas use the same structure, the same geometry and the same engravings as those that were designed at the end of the 19th century. There is another example in the Fine Arts staircase in the Grand Palais.

How does it feel to be working at the Grand Palais?
It is a real thrill to be working in a historic building that has Europe's biggest glass roof.