Did Bob Ross use oil or acrylic?

Bob Ross used oil paint, not acrylic, for his wet-on-wet painting technique featured on The Joy of Painting. He used oil paints specifically because oil stays wet and workable for long time, allowing blending, soft clouds, mountains, and happy little trees directly on canvas without drying quickly. His technique relied on liquid white, which is thinned white oil paint applied as base coat to keep canvas wet and slick, enabling colors to mix and glide. Acrylic dries fast in minutes and would not allow wet-on-wet blending needed for his style. Bob Ross used his own brand of oil paints, with colors like titanium white, phthalo blue, alizarin crimson, sap green, and cadmium yellow, plus large brushes and palette knives. While some modern artists replicate his style with acrylic using slow-dry mediums, authentic Bob Ross technique is oil only. So Bob Ross used oil paint, specifically oil-based paints, not acrylic, because oil's slow drying is essential for wet-on-wet technique and soft blending that defines his landscapes.