This article will address the issues with problems associated with e-liquid and refilling. Although the concept is simple, refilling your cartridges with e-liquid requires a little bit of practice. Below are the most common questions and troubles regarding e-liquid!
For the sake of simplicity, I will refer to the refill cartridge as such:
1. Filter – orange/brown cartridge
2. Tube – cartridge inside of the Filter
(this holds the e-liquid)
3. Filler – polyester fiberfill (cotton-looking stuff) inside of the Tube
How many drops can be placed into the cartridge?
It depends on the size of the e-cigarette and the size of its cartridges. For our Firelight and Opus models, which are roughly the same size as a 100s and standard king, respectively, 2-3 drops is sufficient. It’s hard to give an exact figure, especially since there are so many different models, so start off with one drop and go from there.
Why does liquid leak out after refilling?
Perhaps the most difficult part about the entire refilling process is making sure the liquid does not leak out when you’re using the e-cigarette. The reasons for leakage include overfilling, laying the e-cigarette on its side, and not placing the drops into the cartridge properly. Inside of the Filter, the Tube holds both the e-liquid and the Filler. The drops must make it into that Tube, and any that do not will seep out the side and leak out into your mouth when you use the e-cigarette.
After placing one drop, you may notice the liquid is already pooling at the brim of the Tube. Unravel one end of a paper clip and stick it into the cartridge to move the Filler around and cause the liquid to go down into the Tube. After you’ve done this, you should be able to place more drops into the Tube.
What are other methods of refilling?
One method is the paper clip method. With the end of an unraveled paper clip, you can remove the Tube by inserting the paper clip through the hole on the mouthpiece end of the Filter, as shown in the photo on the left.
Push the paper clip through the hole gently so the Tube comes 
out of the other end, as shown in the photo on the right.
Keep in mind that as you are doing this, you want to keep the filter upright so the e-liquid does not leak. The filter and tube are shown sideways in the photo because, well, I only have two hands and someone had to take these photos! 
Then, you can proceed to refill as you normally would. This method is extensive, more messy, and will take more time to refill, but it can give you a better idea of just how much your cartridge can hold and a better understanding of the “mechanics” of the e-cigarette.
After you are done refilling the Tube with e-liquid, place the Tube back into the Filter and push down on the edge of the Tube with the paper clip to nudge it back into place. Push gently until you can no longer push anymore.
Another method, and perhaps the most popular, other than the traditional drop-the-liquid-into-the-tube method, is to use a syringe or a dropper with a thin neck. Both can be obtained at a CVS, Walgreens, or any pharmacy-type convenience store. Having the long neck of a dropper or a syringe helps out greatly with accuracy.
I refilled my cartridge, but there is no vapor. What’s going on?
Atomizers can “drown” if there is too much liquid in the cartridge. Atomizers should be kept moist but not overly wet. When there is too much liquid in the Tube, the atomizer may not vaporize properly. At this point, what you can do is remove the Filter from the atomizer and soak up some of the liquid on your atomizer by dabbing it lightly with a paper towel. You can also dab the inside of your Filter with a cotton swab to absorb any excess liquid.
And this concludes the most common issues with refilling cartridges with e-liquid. Hope this helps and serves as a handy guide during your refilling venture! 
