Shellite vs naptha? Bark vs pre-powder?

[SpireCatalyst]

I apologize if this is a repeat post, i tried to search but to no avail...Is there any significant difference between the two? SWIM is using a tech that uses shellite but here in the ol' you ess of ay its not readily available, so naptha it seems is my next choice. Any advice would be greatly appreciated, this is SWIMS first extraction, using MHRB. And also plans on ordering approx 250g and didn't know if there is a real difference between bark and powder, powder would be easier but if its unreliable he'll just powder the bark himself. Thanks. oh ya, using the lextek

 

[MIA]

Swim would also love to hear some discussion on both these questions. Bumping an old topic since this is all search yeilded.