I recently bought a house and decided to remove the carpet from the stairs and install hardwood instead. To save money, I decided to buy unfinished stair treads and risers and to finish them myself. This is my first time with woodworking, so please bear with me here.
After researching on the web, I bought sanding paper, oil-based stains and polyurethane, and started working.
My first and perhaps only problem is that despite sanding for a long time with an ROS, the wood just does not seem smooth. The density of the wood seems unequal and I can see small gaps along the grain in some areas. Those areas are smooth to the touch when I run my hand along the grain, but not across the grain. See below:
Giving up on sanding, I decided to apply stain on the surface. The areas with gaps absorb more stain, and it actually creates a good-looking color effect. However, we can clearly see that the darker areas are "rougher":
Applying 2 coats of oil-based poly over this does not really fix the problem. It looks like light reflects differently on the darker areas and it doesn't look very good when placed under the light.
Is all of this normal? Is it because of bad wood quality? Did I just not sand enough?
Thanks for your help.
Note: the wood used is a smaller piece just for testing purposes prior to finishing the actual stair treads.