Swim has some acetone and the MSDS states that it is 99.5% pure, should it be dryed with epsom salts or is the amount of water negligable for fasa precip use ?

Also SWIM thinks somone has a method for drying acetone using a funnel loaded with dry mag sulphate in there blog but Swim cant seem to find it, any ideas ?

Is the .5% impurity clearly stated as being water?

I always added a pinch of mgso4 to my acetone anyway, then I can tell by how it settles in the acetone if it needs further drying.

Yes clearly.

.5% of water is gonna yield very little loss, if you want to go ahead and you epsom for the drying then go ahead.
SWIM should be recycling his solvent, not evapping it.