Here's the material/equipment I've been working with:
Wick: Japanese cotton pads
Wire: only have 24g Kanthal
Juice: Max VG juices, mostly >90% VG (Virgin Vapor, Velvet Cloud, etc)
Builds (all dual coils):
- tried a 0.4 ohm (10 wraps around 2.4mm drill bit)
- also tried a 0.3 ohm with a larger inner diameter (6 wraps around 3.0mm drill bit)
- and even larger ID (6 wraps around 5/32" drill bit) for .35 ohms
- also tried a 0.2 ohm spaced coil (4 wraps around 3.0mm drill bit)
Atty: Plume Veil 2.5
Mod: 18650 Mech Mod (Copper Limitless Mod) or iPV3 Li mod box
Batteries : Sony VCT4s
I only have the Japanese cotton pads, but I've tried more cotton, less cotton, thicker wicks, thinner wicks, longer wicks, shorter wicks, tighter wicks, looser wicks, you name it, I've tried it! I've also tried playing with the height of the coils in relationship to the cyclop air holes on the Plume Veil and I didn't see much of a difference. There seems to be adequate air flow.
I've also inspected the coils for hot spots and cannot see any. Both coils usually heat up at the same time from the center out, and there are no hot leads or anything of the sort.
I've put the RDA on both the mech mod and the iPV3 Li, and I get BURNT hits right off the bat with both, except maybe with the box mod if I vape at lower wattages (around 35 watts or so), then it takes about 3 hits before I get the burnt hit, but any higher wattages and I get the burnt hit immediately on the first hit.