The most common finishes are Swedish finish (acid cured), or a Water based finish (two-component). 

 

Swedish finishes have been used for many years and has a well prove reputation.  It requires typically two coats and is quite durable, wear resistant and is fairly in expensive.  The down side is that a Swedish finish is very toxic, as it contains formaldehydes.  The release of the formaldehyde occurs during the application and one to two weeks thereafter.

 

Water base finishes are environmentally friendly and have been used for about fifteen years.  Good Quality products, which are two-component, are as durable and wear resistant or better than Swedish finishes.  The water base finishes are more expensive and require a minimum of three coats.