After seeing some of the good reviews of the Kanthal 0.9 ohm ccell coils, I bought a 5 pack of those.
Burnt taste, even after a long prime. Verrrryyy harsh. Searching the internets I found many reports about this, like here. It seems there has been (is,are) a batch of those 0.9 ohm Vaporesso ccell Kanthal coils with a manufacturing error. Even letting it sit, seems to dry up the coil after a while.
After unsuccessfully messing about to find a solution, I have 2 ccells of my 5 left.
So I tried a highly unscientific "method":
I let a *new* coil soak in vinegar for half a day. Rinsed it with hot water. Then, soaked it in hot water with a good load of dishwashing soap for an hour. Rinsed it thoroughly with hot water. Dried it for a day, in front of a fan.
Now, I just tried it on one, and maybe either of the above steps may be skipped, but I tried the coil, just gave a bit of juice in the center, and a minute in a full tank. A few vapes at twenty watt, a few at 25, and then to 32.5 watt. It tastes normal, even good now. No burnt taste.
It may work for you, or it may not.