"The Singing Choir of Della Robbia' shows Frank Mason's striking use of light and color. Mason mixed his own paint materials to get his infinite variations in shades.

The tranquil "Peacham New Moon" is one of Frank Mason's landscapes that celebrates a summer home he and his wife shared in Peacham, Vt.

Frank Herbert Mason, who died this past summer, was a rare artist who studied and used the paint materiials of painters from the 17th and 18th century. His first posthumous show opens at New River Fine Arts Gallery.

Frank Mason may be gone, but he still smiles out at the world from his own Facebook page. It’s a wonderful resting place for an artist who was forward-looking as a teacher, writer and art preservationist, even while he grounded his light-infused painting in techniques centuries old.

Mason, vocal protector and student of the masters’ art, died at age 88 on June 16. New River Art Fine Art Gallery, 600 Fifth Ave. S., is opening the first posthumous show of his available works Friday: paintings and the portfolio of Mason’s drawings for his vast “Gloria in Excelsis Deo,” a series of 68 oils and 139 drawings that explore the life of Christ.

For New River consultant John Gillespie, this show will be like spending his days amid the luminous colors of Rubens and Rembrandts. Mason was one of the few artists in the world who knew how they created their paints, having studied extensively with the late Jacques Maroger, the Louvre’s lifelong detective of chemistry in the masters’ oil-based media.

“Frank was an amazing man. He could have had a career in contemporary art — easily — and made millions. But he dedicated his life to this kind of art, and there was no one like him around today,” Gillespie said several days before the opening Thursday reception.

Gillespie has been watching Mason for at least 15 years, from his own gallery in Pittsburgh and through two galleries he’s worked with here. Although this show may be exhausting for Gillespie because the gallery is just coming off an exhibition embracing four generations of Pissarro family works, just talking about Mason re-energizes him.

“He was an unusual man who stuck to his principles. And because of that he created work that no one else today really can,” he said.

It’s a fortuitous show for buyers, since Mason’s work is rated as a good purchase, and comes ahead of the potential publicity from an upcoming documentary, “The Maestro Upstairs,’ scheduled to air on PBS next spring.

Maestro? “He was an incredibly talented pianist. He had a piano in his studio and sometimes students would come and he’d simply play for them,” Gillespie said. “And he was a wonderful writer. That’s how he was able to get the attention for the problems in art preservation that he did.”

Mason raised an articulate and continued warfare against the treatment of famous art, which he saw as being ruined at the hands of overzealous restoration. Among his targets were the Sistine Chapel, where Michelangelo’s ceiling frescoes were apparently being cleaned down past their varnish into and through some of the gradient colors that gave the works their dimensions.

In 1975, Mason and some of his colleagues and students protested in front of the Metropolitan Museum of Art in a publicized event that reflected his beliefs about professional conservation of the day: “The least safe place for your paintings is a museum; they will be skinned alive.”

Mason and art analysts and conservators who in ever larger numbers began to agree with his observations, founded the group ArtWatch, which publicizes questionable lending or sales and harmful restorations. People outside the art world will know them as the sentinel of the oncoming Taliban campaign to destroy historic Buddhist art in Afghanistan.

A realist in a world of expressionism, abstraction and installation, Frank Mason never strayed from his decision to depict, in sumptuous color, scenes from life around him. Until late in life, he hand-ground the pigments for his own paints to get precise colors and prepared his own canvases. He never painted from photographs, which he felt was reduced the artist’s understanding of the living being to photocopy-ism.

That dedication did not guarantee Morgan a place in the avante-garde show halls of Art Basel. But it created a market in lofty places: a Mason painting hangs in the Church of San Giovanni de Malta in Venice; his commissions are in the King Faisal Naval Base academy in Saudi Arabia and behind the altar of St. Patrick’s Old Cathedral in New York.

He was a member of the invitation-only Salmagundi Art Club and for 57 years taught at the Art Students League of New York, alma mater to names such as Georgia O’Keeffe, Thomas Hart Benton and Will Barnett.

This show has some of Mason’s most evocative work: his evocative “Block Island Beach Scene” and his dramatically lighted “Garden Glory.” Drawings in sepia chalk distill his graceful drawing and constant eye for color effect, as in the bright bolt of white in “St. Paul with Roman Soldiers in Landscape,” and “Angel of Death,” created on green gesso.paper.