I needed a VG option for my last fluid PG/VG proportions. I made a 10% BA option in VG by mixing 10g Bachelor's Degree with 90g VG. Warm was applied up to 55 levels C as well as the mixture was stirred and drunk to liquify as long as feasible. Thinking that the specific gravity of VG is 1.25 we then have an option including 138mg/ml Benzoic acid. Mixing 6 mg base with nicotine-free base will constantly give you much less than 6 mg because of this. Try getting some 12 mg base and blend it with the nicotine-free base at a 50/50 proportion.