It penetrated the wood and filled the pores like a primer. It sands and fethers very well, which means it will be easy to repair. I was not impressed with the gloss though. I am going to check with the rep to see if a additive can help the gloss. There are some alternative to consider if you wish.
Urethanes are very difficult to repair.
It adheres to all types of surfaces. My KR2S sits painted with Smooth Prime awaiting it's top coat. Something that I thought I'd be doing last year.