All e-liquids containing nicotine at point of purchase are limited to a maximum liquid amount of 10ml per bottle and contain no greater than 20mg of Nicotine per 10ml bottle. This is why you are not able to buy nicotine containing e-liquid in larger formats. This legislation was put into place by MHRA, commonly known as TPD legislation (Tobacco Products Directive). This was put into effect in 2017 and still active today, other rulings also affected the maximum capacity of tanks, pods and liquid containing devices.
Nicotine shots (nic-shots) are often used with shortfills, they still go through all of the necessary testing and approval with MHRA, and come in 10ml bottles as per TPD. These are then mixed with the shortfill to suit your requirements and ultimately you are left with a larger bottle that has your desired strength of nicotine. Doing this is fine as it still preserves the rules and follows the strict testing required, but it is a slight swerve on the rules only for the convenience of the customer.
Nicotine shots are usually flavourless, so they will not affect the final flavour. Some may be available as a menthol or ICE option, giving your liquid a menthol or cool sensation when you vape it.
Shortfills do not contain any nicotine at all. They are therefore not restricted in bottle size, so consumers are able to buy e-liquid in a number of different liquid volumes (50ml, 100ml, or greater). The most common shortfill is the 50ml as this seems to be the sweet spot for price, mixing and also how much you may use before you feel like a change in flavour.
Those looking for a way to get their e-liquid in a more convenient and cost effective format are the reason shortfills were invented.
Starter devices use low amounts of e-liquid during use, but many devices especially those in the intermediate and advanced categories, can easily use more than 10ml of juice in a day, so having just 1 bottle to carry around is much easier than multiple small fiddly ones.
The name `Shortfill` is derived from the bottle looking like it has been filled short, which it has but for good reason! It is to allow space for nicotine shots to be added! A 50ml shortfill will have a 60ml bottle, but you will be getting 50ml of E-liquid, the remaining 10ml of space is for if you decide to add nicotine shots. A 100ml juice will come in a 120ml bottle.
The general rule of thumb is for every 50ml of actual juice supplied, manufacturers will allow an additional 10ml of space in the bottle size in case you wish to add nic-shots.
When you have a shortfill, you can add a nicotine shot or nicotine concentrate to then convert your 0mg (nicotine free) liquid into one which now contains nicotine. The shortfill and nic-shots when mixed will yield the most common nicotine strength of 3mg but you can blend it any way you like to get your desired strength.
The way to work out your nicotine strength is quite easy; you just have to know what you’re aiming for as the final result. You can calculate this using the following calculation.
Let’s say you want to end up with a 3mg e-liquid and you start with a 50ml, 0mg shortfill. The nicotine shot you would need is an 18mg (1.8%) one.
TOTAL VOLUME OF NICOTINE ÷ TOTAL VOLUME OF E-LIQUID
= FINAL NICOTINE STRENGTH
Shortfill liquid volume = 50ml @ 0mg
Nic-shot liquid volume = 10ml @ 18mg (1.8%)
You take the total amount of nicotine which is 18mg (1.8%) in this example, and then divide this by the total amount of e-liquid 60ml (10ml+50ml=60ml). This will give you the result of 0.3% which is 3mg.
18 (1.8%) ÷ 60 = 3mg (0.3%)
50ml Shortfill + (1x) 18mg shot = 60ml @ 3mg
50ml Shortfill + (2x) 18mg shot = 70ml @ 6mg
100ml Shortfill + (2x) 18mg shot = 120ml @ 3mg
100ml Shortfill + (4x) 18mg shot = 140ml @ 6mg
If you want, you can use this link to type in the numbers and let the calculator do the work. It will show you how many ml’s of the nicotine shot you need to add to your e-liquid to get your strength.
Adding multiple nicotine shots may dilute your juice slightly as you are effectively watering your shortfill down. This is only more noticeable if you are adding multiple nic-shots to your juice.