With any refinishing of wood work there are always surprises lurking underneath the darker colours; usually in the form of damage, previously repaired damage, or poorly repaired damage that must be dealt with.
I use Mohawk Finishing Supplies and their products for the most part; Mohawk has everything I need to repair and finish a piano along with years of experience in the products and the use of them.
The owner of the Mohawk franchise here in Vancouver, has regular presentations and workshops one can attend here to learn the proper use and applications of their products.
Of course these products can be purchased from any of the furniture refinishing supply houses.
Piano Cabinet Repair Supplies