The Raising of the Cross is on display in the Bredius museum after art experts confirmed it was a genuine Rembrandt, not a fake as previously thought. Photograph: Koen van Weel/EPA

It was always believed that the Dutch master’s disciple painted The Raising of the Cross, but today, according to experts, Rembrandt painted it himself

An oil drawing by the renowned Dutch artist Rembrandt that was thought to be a copy and had been neglected for a century has been revealed by art experts in the Netherlands.

Long believed to be the work of a pupil of the 17th-century master famed for works like The Night Watch and The Anatomy Lesson of Dr. Nicolaes Tulp, the 1640s oil sketch Raising of the Cross was originally created.

The drawing, which has been on display at the Bredius Museum in The Hague since it was purchased in 1921, was identified as a Rembrandt painting on Thursday according to modern scientific procedures.

Johanneke Verhave, who repaired the drawing, remarked, “The quality of the details are so well done that I am convinced that this is a Rembrandt.”

Painting partly obscured by heads of people viewing it closely. The image is mirrored in a reflective wall on the right

Crowds gather to inspect the newly verified Rembrandt on Thursday. Photograph: Koen van Weel/EPA

The picture was initially “rediscovered” by Jeroen Giltaij approximately a year ago while doing research for a book on Rembrandt. They examined it together. Giltaij was the former head curator of ancient paintings at Rotterdam’s Boijmans Van Beuningen museum.

“I looked at this work again and again. At the brush strokes. They are brilliant,” Giltaij told Agence France-Presse. “Just a few broad brush strokes” convinced him the sketch was indeed the genuine article, he said.

Abraham Bredius, the founding curator of the museum, made his first purchase of the artwork in 1921. Like others, he believed the drawing to be an original by Rembrandt. However, over time, art professionals regarded it as a “crude imitation.”

For his Big Book of Rembrandt Paintings, which includes all 684 of the Dutch master’s pieces, Giltaij reexamined the drawing.

“When I was looking at it, I thought Bredius was right. I think this is indeed a Rembrandt,” he said.

The apparent lack of detail in the brush strokes was one of the primary justifications made by art experts to support their claim that the drawing was an imitation.

“You have to remember, this is an oil sketch. Rembrandt is usually very precise and refined, but this is very rough,” Giltaij said. “The reason is the oil sketch is a preparatory sketch for another painting. He wants to show the composition, a rough idea of what the actual painting could look like,” he said.

The drawing also reminded viewers of a Rembrandt painting from 1633 with the same title, The Raising of the Cross, which is now on display at Munich’s Alte Pinakothek.

Infrared reflectography and X-ray scans of the drawing, according to restorer Verhave, revealed intriguing details. According to the study, the artist made multiple adjustments to the drawing as it was being painted, indicating that the composition was the result of a creative process. “This indicates that the painter was altering his thoughts as he worked. It was obvious that he wasn’t imitating another artwork.

The study also revealed that the painter’s brush technique matched that of the renowned master.

The Rijksmuseum in Amsterdam received the study from the two specialists and did its own examination. The Bredius museum said, “Regarding the utilization of materials, the researchers of the Rijksmuseum could not uncover anything to refute an attribution to Rembrandt.

Thanks to Agence France-Presse at The Guardian whose reporting provided the original basis for this story.