"How do I know when my coil is ready to be used in a vape tank?"
The coil within a vape tank is probably the most important component and needs to be primed correctly before use. The act of priming a coil, simply, is ensuring that the wicking material within the replacement coil has been saturated sufficiently leaving no areas of the wicking material dry. If there are dry areas within the cotton, these could easily burn giving not only a foul taste (known as a dry hit) but also decreasing the lifespan of the coil.
The easiest way to do this pouring a few drops of e-liquid on to the wicking channels which are usually located around the base of the coil. After this has been completed, we would also advise dropping a small amount of e-liquid directly into the top of the coil (this can be performed as many times as needed) so it saturates the cotton thoroughly.
After you have partially reassembled your tank you will then be able to fill this with e-liquid. I say partially as some tanks will need the top cap to be removed in order to be able to fill the tank with e-liquid. There are also other versions of how to fill a tank such as the top cap can slide to the side revealing a filling port.
Some of the older styled tanks, such as the Aspire Nautilus Mini are bottom fill. This would require you to turn the tank upside down (drip tip facing the ground) and unscrew the base of the tank. The coil will normally come out with the base and there will be a central chimney which you can use as a filling guide. Do not overfill a bottom fill tank, otherwise the e-liquid will travel along the inside central channel and come out of the mouthpiece.
One your tank is full with your prefered e-liquid, then you can seal the tank in whichever way is relevant to you and leave it to sit for four or five minutes.
After this time has passed, it is then advised to take a few primer puffs on your tank. Primer puffs are when you take a pull on the tank as normal but you would need to close off the airflow as much as possible and not press the firing button. This will force e-liquid to be pulled through the cotton removing any remaining dry areas. Please do not take more than 2 or 3 primer puffs to avoid flooding your tank.