Primarily known for his landscapes of Lyon and its surroundings, Bas specialized in pastels, a medium he adopted due to his fragile health, as his paint box was too heavy to carry. Always working en plein air, he was captivated by the changing light along the banks of the Saône. He excelled in depicting the transparency of water and mist, using long, subtle strokes. Avoiding the conventional landscapes typical of watercolorists, he focused on locales such as Villeurbanne, La Mulatière, Fourvière, and La Villette.
His style departed from traditional Lyonnais painting, drawing inspiration from Fauvism. His works are characterized by broad, generous brushstrokes, marked by a strong and ample touch. However, Bas destroyed much of his own work, favoring the spontaneity of quick sketches (pochades) over fully finished canvases.
He passed away at just 41 years old in 1925, succumbing to tuberculosis, leaving behind a sensitive and luminous body of work.