Do we really have to sand the table before we varnish it? Can't we just go over the old coat?

How to say “Do we really have to sand the table before we varnish it? Can't we just go over the old coat?” in French

In French

On est vraiment obligés de poncer la table avant de la vernir ? On ne peut pas juste passer une couche par-dessus l'ancienne ?

Do we really have to sand the table before we varnish it? Can't we just go over the old coat? in other languages