Not a putty knife !!! Pallet knife is the term !! Its a widely used tool to create texture on the surface !! I use it mostly for mountains or rocks & trees but many artists paint the entire scene with a pallet knife !! I just like the combination of soft and hard myself !! Haven`t looked up your artist but if that is what his auction/sales show then yours would fall into the same catagory !! Subject matter is of importance to the buyer and will not make a huge difference in money on an outright sale !! Especially if the artist is not widely collected !! And from those sale figures it sounds like he is not !! Have you checked ebay to see if there are any of his paintings there ?? If so, see if anyone is bidding on them !! Sometimes lesser known artists just do not sell at all !! Especially in this economy !!