I use oil and wax for plywood. It is an impregnation based on modified vegetable oils. For uniform distribution, the agent is applied to the pre-sanded surface with a brush, roller or cloth swab. Excess impregnation is removed with a clean cloth. This was suggested to me at https://zelta.ca/services/staircase-renovation/ when we ordered the flooring in the kitchen. And there is always high humidity.