I found Rayon to be better for wicking. Could be the tank is not filled enough or flavouring is building up in the wick and clogging up the flow. A rewick should fix the issue though. I found jeremyr's thread very helpful. The first post explains everything. The only difference from using cotton is cotton expands when soaked with juice where rayon contracts/shrinks.
This means Rayon needs to be packed very tight into the coil while cotton needs to be much more loose. The Avocado is the first RTA I've got working great.
Read the first post here, it may help you, it helped me a lot, it works!
Rayon Wick - Better Flow, Flavor, Longevity, and Nic Hit!! - Pt.2
Love it! Cheers.
First of all, thanks for the response and recommendation. I might look into rayon cotton. Secondly, as oppose to the tank filling issue, I always keep the tank filled whenever it hits 40%. Furthermore, I change the cotton whenever there's prolong dry hit. Thirdly, I always ensure the cotton doesn't sits very tight in the coil itself. Besides that, I have tried experimenting with the length of cotton and the thickness of the wick.
There are two observations that i found whenever there's dry hit, one being the cotton is dried up, meaning the juice doesn't flow fast enough, second being the cotton turned reddish (the juice i used is yellow in color, not sure about the pg/vg, but nicotine is 6mg, bottle is 100ml and I have dilute it with vg for half a bottle).
Currently, my dilemma is that I followed tutorials from youtube thoroughly yet I keep getting dry hit, but at just 20watt.
edit: misconception on my part, I have been getting fry hit, as in the cotton turned white more than burn hit, the cotton turned red