In this video

The final step, as mentioned in the video, is to seal the stained wood. This is particularly important for stairs, which experience heavy foot traffic and require durable protection. Apply a high-quality clear protective finish, such as a polyurethane or a floor-grade wood sealer. Apply multiple thin coats, allowing adequate drying time between each coat as specified by the product manufacturer. For best results and enhanced smoothness, lightly sand the stairs with a very fine-grit sandpaper (e.g., 220-320 grit) between coats, then wipe thoroughly with a tack cloth before applying the next coat. This sealing process protects the stain and the wood from wear, moisture, and scratches.