Handmade stained birch stool. Stained birch is a unique 100% natural material. Stained birch is lifted from the depths of rivers after spending at least fifty years under water. After special drying and processing, stained wood becomes extra strong and non-sensitive to any external factors, like excessive moisture or dryness. That is why ZET, like other stained birch products, has an unlimited service life and maintains the original beauty of natural wood.