I went to my local hardware store to buy another can of naptha and there was none on the shelf. I asked a store employee and was told that naptha could no longer be sold in Los Angeles County until it was "reformulated" whatever that means. I tried a couple other stores and found the same thing. I did locate some Ronsonol (last can) in one local grocery store.
The hardware stores do have "mineral spirits" which the can says leaves no residue and I wonder if that is an acceptable substitute for cleaning shutters, etc. Does anyone know?