The panels - now on view in Antwerp - represent the story of John the Baptist and were painted by order of Queen Isabella of Castille in the late 1400s for the Miraflores cloister in Burgos in Northern Spain. In the early 19th century, the altarpiece was split, with the panels landing in various museums and collections.

Juan de Flandes is one of Flanders' masters (although he only found fame once hired by the Spanish court), and so it is only right that two of the five panels wound up in the hands of the army of conservationists, historians, scientists and photographers of the Royal Institute for Cultural Heritage.

It was here in a quiet, sunlit atelier overlooking Brussels' Jubelpark where I met Livia Depuydt's team of painting conservationists and restorers as they put the final, painstaking touches to these oak panels, which include the scene from the banquet of Herod where a young woman serves up John the Baptist's head on a platter.

Conserving History
Pre-empting any purist streak I might have, Depuydt begins by telling me the principles of the institute (known locally by its Dutch initials KIK): there should be as little intervention as possible, it must be reversible, and it should be invisible. But that's only after the artwork has been studied, photographed, undergone radiographs, cleaned and any loose parts fixed.

All the artwork that arrives at KIK is subject to the same routine. Just as an indication of how busy these folk are, the digital photo library boasts more than one million images, keeping an accurate record of every piece that passes through these doors. And taking all these images is also part of the conservation process.

"Of course, we examine an artwork with the eyes," says Depuydt, but her team also uses radiographs to determine the condition of a piece and infrared images to see underlying sketches, which can give crucial information as to the techniques employed by the artist.

The next stage is to ensure that the work can hold up to restoration techniques. "If things fall apart, then it's finished," says Depuydt. Then, the work has to be cleaned. "Varnish, for example, turns a painting yellow over time, so we have to remove the varnish," she explains. Only then does the delicate task of touching up a painting begin. Depuydt explains that her workshop uses stable pigments - "so that the colour we add doesn't change over time" - and uses products that differ from the original. "This is to ensure reversibility."

Any previous attempts to restore the paintings are left in place. "If it's well done, then we leave it there. We don't take it away just to redo it," explains Depuydt. And while the principle aim is to conserve the paintings, I get to watch as a restorer, working on one of the panels, carefully rebuilds a detail, using other works by Flandes as a reference.

Holistic approach
The raison d'être of the institute is to provide a one-stop shop for curators of public and private collections. Aside from the painting atelier, there are specialised units dealing with textiles (hardly surprising given Belgium's long tradition in tapestries), metals, glass and stained windows and sculptures in polychromed wood.

Stopping off in the textiles department, director Fanny Van Cleven shows me some pieces that have definitely seen better days, with either holes or which have been mended with bright fabrics that clash with the original work. Much of KIK's work involves providing backing support for these delicate, aged fabrics and repairing the damage.

"We try not to add too many materials or colorants. We put support behind a hole so that the weight of the fabric doesn't create any tension, and what we add is always very neutral." explains Van Cleven, showing me some creamy coloured tapestry wools used to fill in the gaps.

Over in sculptures, another artist is carefully removing layers of paint that have been added to a statue of Christ on the cross. "Sometimes, it's easy. We can use a solvent to remove the paint layer," he says. But in this case, that's not possible so he's removing the layers with a scalpel and a microscope, a project he describes as a multi-year task.

Finally, the pièce de resistance is the laboratory where analysts study a painting's pigments and binding agents (egg whites were often used in paints) and ascertain the condition of some of the nation's treasures. I spy a slab of stone from the Stoclet Palace, a UNESCO heritage site on the Tervurenlaan in Brussels, which is being checked for porosity.

Now that they've received their holistic treatment, the two Juan de Flandes panels join two others for a special exhibition at the Museum Mayer van den Bergh in Antwerp. The exhibition includes an explanation of the work that was carried out by KIK. The fifth panel - in fact the central panel, which is the largest - is in a private collection in Madrid and too delicate to be transported.

Juan de Flandes and the Miraflores altarpiece
Until 7 November Museum Mayer van den Bergh Lange Gasthuisstraat 19 Antwerp
http://tiny.cc/mayervandenbergh

Keeping it real
The discovery of a painting that's possibly by a famous artist is a thrilling occasion, but it doesn't always have a happy ending, thanks to the many fakes that haunt collectors' nightmares.

Earlier this year, a painting from a private collection thought to be by Wassily Kandinsky was sent to KIK for analysis. Alas, this was yet another of the Russian avant-garde forgeries that flooded the market in the post-Cold War era.

In the wake of Perestroika, Western collectors became keen on paintings of this genre, which are from about 1900 to 1935 and include schools such as Futurism and Abstraction. The Kandinsky painting had followed in the footsteps of a series of paintings attributed to Liubov Popova, which were also found to be copies thanks to the highly specialised techniques used by the institute to examine the pigments in the paints.

Steven Saverwyns, head of the institute's laboratory (which is dominated by space age machinery I can't possibly ever understand), is keen to emphasise that minimum interventions are made to ascertain authenticity.

Most commonly, the tiniest sample of paint is taken to measure the colour spectrum of the pigment, although the institute now has a laser system that takes images without requiring samples. The spectrum is compared to samples in a digital library. With synthetic pigments in particular, the institute is able to determine their earliest usage.

In the case of the Kandinsky piece, pigments that post-dated his lifetime were found, allowing KIK to confirm that, unless he had come back from the dead, the painting, while beautiful, was definitely not his.

www.kikirpa.be