You have what appears to me to be Yellow Pine treads which are generally covered with something if used in the main living portion of a home. The risers would be a different material (comommon pine, FJ pine, plywood are the most common), and as such all will take stain differently. Just something to consider.

Before you go cap treading its better to first understand Run and rise along with FFT. Finished floor thickness at landing and adjoining levels along with maximum nosing compliance.. Theres a lot of handymen that will gladly put you right out of code compliance while taking your money and installing topical cap treads. Your local municipality should have clear staircase compliance on their website or in office.

I am considering cap a treads so I wonder the cap a treads held on the long run? Still happy about this option? Thanks.