Giotto's Santa Croce frescoes are receiving the final touches of a four-year restoration in Florence, with scaffolding poised to be removed ahead of an official reveal in September.

On Friday, journalists were invited onto the scaffolding that has obscured the view of the famous 14th-century frescoes adorning the walls of the Basilica of Santa Croce's Bardi Chapel.

Estimated by art historians to have been begun sometime after 1317, the frescoes are considered to be one of Giotto di Bondone's masterpieces.

The painter and architect, hailed as the father of the Italian Renaissance, is believed to have been born around 1267 in Vicchio, just north of Florence.

He was celebrated during his lifetime for introducing a new way of painting — depicting weighty, massive figures in three-dimensional space, while imparting his characters with a human expressiveness not seen before.

Renata Pintus, who heads the masonry department at the Opificio delle Pietre Dure, Florence's famous restoration workshop, told Agence France-Presse (AFP) it had been a "privilege" to work on Giotto's famous fresco cycle.

"Perhaps the greatest emotion is feeling a bit as if you were up on the scaffolding with Giotto ... retracing the creative phases in the making of a masterpiece like this," she said.

Once virtually lost to memory after being painted over with whitewash, the frescoes began to be uncovered in the mid-19th century, but the work left scratches and pockets of white on the frescoed walls.

The last restoration work was carried out from 1957 to 1958.

From the scaffolding, restorers have been meticulously filling in damaged portions of the frescoes and conservatively layering paint over bare sections with delicate brushes, their hands protected by gloves.

The team decided to remove filling from previous restoration work, replacing it by mixtures of lime and sand that more closely resembled the original material used by Giotto.

"We tried to resolve the conservation issues affecting these wall paintings, caused by their long and rather troubled conservation history over the centuries," Pintus said.

But the partially destroyed frescoes have offered up a bright side, she said.

In some cases, the lost paint layers revealed "preparatory stages" where Giotto laid out his figures or architectural elements before the final layer, said Pintus.

After addressing structural problems such as loss of adhesion and exfoliated paint, the restorers then used reversible techniques - including watercolor paint - to "stitch" everything back together, she said.

Stefano Filipponi, head of the Opera di Santa Croce, which manages the church and oversees its conservation, told AFP that visitors will notice the difference when the frescoes are officially unveiled to the public in September following the renovation, which has cost more than 1 million euros ($1.16 million).

"They will certainly be able to appreciate Giotto's painting with greater clarity because the work carried out today, using the technologies we now have, has made it possible to free the original painting completely from any kind of glaze or covering," he said.

"It is something extremely direct, narrative and engaging," he said of Giotto's work.