As a top student of Prof Silpa Bhirasri, the father of Modern Thai Art, Sawasdi became one of the few Thai artists, including late masters Jirt Buabusaya, Fua Haripitak, Tawee Nandakhwang, to draw on European movements such as Impressionism, Post-Impressionism, Expressionism and Cubism.
After graduating from Silpakorn University in 1948, Sawasdi studied further at the Academy of Fine Arts in Rome, where he learned Western art techniques and later shared them with his students at Silpakorn University, where he taught until he retired.
Known among his thousands of students as "the gentle teacher", Sawasdi's legacy continues with his son Parinya, who is also an art lecturer.
Being a long-time fan of the master's work, I was given a chance to interview him a few times. He spent most of his life capturing nature on canvas, be it the sand and the sea, mountains or even his garden at home.
"Working with water colours requires determination. Art, especially painting, has become a part of my life," the artist once said.
"Most of my pieces reflect nature, which is the main source of my inspiration and serves as my master and teacher. I'm very proud and happy to create these works and will be even more happy to see my audience consume this inspiration and share their dreams with me through painting."
Even immobility couldn't stop Sawasdi from putting paint on canvas. Sichang Island in Chon Buri was one of his favourite places. On weekends, he would pack up his painting materials and catch a bus on his own to the island. He had been doing that for decades. He also loved fishing, which probably explains why many of his paintings capture the charming scenery of fishing boats.
Seven or eight years ago, I was given the opportunity to cover a painting study trip to Cambodia with Sawasdi and other Thai artists. The master was one of the most productive in the group, spending hours sitting in front of Angkor Thom or Angkor Wat, waiting for just the right light to shine on the World Heritage Site. He was always the last one to make it back to the bus.
Last summer, the National Gallery hosted a "Retrospective Exhibition by the National Artist Sawasdi Tantisuk". This was the last chance admirers had to marvel at the master's works during his lifetime.
Though some of his pieces still hang at the National Gallery, some belong to local collectors, international art museums and private collections overseas.
His works, that have often been put under the hammer at Christie's and Sotheby's, were known to bring in millions of baht.
With Sawasdi gone, Sichang Island will be lonely.
Still, his efforts to lay a strong foundation for Thai modern art will always be remembered and preserved for the next generation.
Rest in peace, Acharn Sawasdi. Through your masterpieces, your spirit will live with us forever.