On the safety of handling nicotine:
You must buy and use nicotine that is diluted to 100mg/ml or lower. Nicotine can be absorbed through the skin which can potentially lead to an overdose causing death or significant injuries in large enough quantities. Therefore, you should NEVER buy pure nicotine, 1000mg/ml, and attempt to dilute it. Even if you were able to do it safely, the end result would be an incredibly harsh and of low-quality, nicotine solution.
Ideally, you'd wear latex gloves, eye protection, and clothing that can quickly be removed before seeping through to your skin. The methods outlined in this tutorial for adding nicotine into e-liquid limit the exposure risks. But, I'd still like to inform you on best practices.
If you happen to get diluted nicotine on your skin follow the instructions on the packaging, usually being: Wash the area with cold water, not warm or hot water, as quickly as possible. If you get it in your eyes rinse them for 15 minutes.
I have personally experienced accidents with both skin and eyes. The skin exposure accidents, 2-3ml, did not personally affect me in any way following rinsing with cold water. The eye exposure accident happened after getting a small amount on my hands and rubbing my eyes. It was painful but no long-lasting effects after rinsing.
On safely storing nicotine:
Nicotine is technically a poison and precautions need to be taken to ensure that only adults are able to have access to it along with correct labeling. I read of a death occuring because the parents put nicotine in an unlabeled dixie cup on the table and a toddler ended up drinking it. So, exercise caution and come up with safeguards to protect your children and animals.
Cautions aside, the degradation of nicotine is greatly accelerated from light exposure and heat. Store it in a cool dark place and if you bought in a large quantity you might want to store it in a freezer. It will not freeze in either a PG solvent or a VG solvent. It will, however, become very thick and unwieldy if using a VG solvent.
100mg/ml or lower, Nicotine. We use Nudenicotine's "Smooth" line of nicotine salts in a 100% VG solvent.
2oz Boston Round Dropper Bottles with dropper preferably amber. You will need one for nicotine and one per base flavor used.
A labeling method of some sort for the flavorings and end product. We use a label-maker with a white tape background. But masking tape and permanent marker would also work.
Condiment squeeze bottle used in place of a VG pump for personal use:
Juice Bottles, we use 50ml bottles with transparent black caps. You can use whatever size you want though:
Vegetable Glycerin, we used to use essentialdepot but when the pandemic hit and people were making their own hand sanitizer, they price gouged from $20/gallon to nearly $70/gallon. So I've been using heartlandvapes as a source for VG instead.
Propylene Glycol, PG is only required if you need to use a flavourart flavor for your recipe, or if you wish to change the VG/PG ratio. You will not need very much and if you wish to buy from another source make sure that it is USP quality.
Note on flavourart: If your recipe requires a flavourart flavoring, dilute 1 part flavoring and 5 parts PG before following the recipes outlined.
1. Label your 2oz dropper bottles with their appropriate labels for every flavor, one for PG if you are changing the VG/PG ratio, and one for nicotine. If you have rubbing alcohol it might be worthwhile to wipe the outside down and let it dry to make sure the label sticks well. You should do this first as if the bottles get flavoring on them the labels won't stick.
2. Pour your flavorings into the labeled bottles. Carefully, while taking the aforementioned precautions, pour your nicotine into it's correctly labeled bottle.
3. Pour your VG into one of the condiment bottles.
Making a bottle of juice:
1. Label your juice bottle first as it might not stick if you happen to get liquid on it.
2. Figure out how much nicotine you need to add to create the required potency I.e 3mg/ml. During the hiring process at the shop I will make my employees sit down and solve this problem themselves so that they fully understand how and why the formula works.You are welcome to do that now, but I will also give the solution and try to walk you through how and why it's true. "You have a diluted nicotine base of 100mg of nicotine per milliliter. How many milliliters of the nicotine solution do you need to add to a 30ml bottle in order to make the 30ml bottle of e-liquid 3mg/ml?"
Answer is.X = Size bottle in ml (30ml)
Y = Nicotine requested in mg/ml (3mg)
Z = Amount of nicotine in your nicotine source in mg. (100mg/ml=100)
So first you need to figure out how many mgs of nicotine are needed to make the bottle have a certain dilution. So the total volume wanted multiplied by the requested mg/ml will give you that. So if you want a 30ml of 3mg/ml nicotine then you will need 90mgs total of nicotine in the bottle. Second you need to figure out how many milliliters of nicotine of your nicotine source you need. So you simply divide the product of size*nic by the strength of the nicotine that you have. So you need 90mg to make a 30ml bottle and our nicotine source is 100mg/ml so 90/100=.9 so we'd need .9ml of 100mg/ml nicotine to make a 30ml bottle at 3mg/ml.
3. Add the nicotine to the bottle. The method outlined here is not exactly precise but should be fairly close.
A full dropper=1ml of nicotine.
If you wish to have a more precise method for how much nicotine you are adding, which I'd advise if you are making over 12mg; I'd recommend using a scale that can measure in increments of a tenth of a mg and use the weight of 1.5mg for 1ml of source nicotine or weigh your own. We personally use one of these instead https://www.amazon.com/BrandTech-Glass-Seripettor-Bottletop-Dispenser/dp/B004PLMDWI which I can recommend, but I personally don't think it's worthwhile on a small hobbyist scale.
4. Add flavorings. The recipes outlined are to make a 10ml bottle. So you'll have to multiply the recipe by the size bottle. If you want a 30ml you multiply by three. 50ml, multiply by 5 and so on. The numbers are in ml and I use the "full dropper = 1ml half dropper=.5ml" etc.
5. Add VG. Use your condiment bottle and try to barely stick the tip in so that there is an air-gap between the nozzle of the condiment bottle and the spout of the juice bottle and squeeze until the juice bottle is full.
6. Cap the bottle. The little clear needle nozzle is press-fit into the top of the bottle and then the screw cap goes over it.
7. Shake the bottle.
Think towards whether what you are doing would be considered "food-safe". Make sure you store the juice bottles in a manner that they are protected from dust. The dropper bottles are a good design to use in this setting as everything is contained within the bottle itself, but wipe them down occasionally anyway. Make sure the lid on the condiment cap is closed. For cleaning anything use food safe cleaning solutions like dish-soap.
Making your own recipes:
If you wish to branch out from my recipes and make your own, I'll leave you with a few rules of thumb. NEVER use non water-based flavorings. If they are oil-based flavorings, ie extracts, you will end up in a hospital and potentially die or have life long irreparable lung damage. I do not recommend going to Walmart and picking out whatever flavorings they are selling without properly researching whether it is water soluble first and verifying. ONLY use water-soluble flavors.
20% flavoring rule. In general try to keep your recipes to around 20% flavoring. This will keep your pg/vg ratio around 80vg/20pg as the flavorings are PG. If you use too much flavoring, the flavor will actually change from it's intended flavor to something different. It will also be slightly more harsh.
Landing note. If you are creating a flavor and it tastes too "airy" or perfumey you need a landing note flavor. A stronger flavor that grounds the rest of the supporting flavors. A lot of my more simple recipes tend to follow a 1ml flavor a .5ml flavor b .5ml flavor c formula, the 1ml typically being the landing flavor but not in all cases. Whipped cream is a good example of an airy flavor. Without anything else it doesn't taste good, but if you were to pair it with vanilla it would taste ok and then if you were to take vanilla, whipped cream and then add a custard with a fruit it would be good, or just a caramel. Basically I'm saying that there will be recipes that you try where it needs a "landing note" to work.
Similarity in flavor profile. Find a flavor that you want to use and smell it and try to think of complimentary similar flavors that would go well with it. Try that, if it needs a landing note add a landing note. Occasionally you can find interesting opposites that surprisingly mesh well together. The cool thing about making e-liquid is you aren't bound to physical limitations like you would be with food. Like you could mix cotton candy, whipped cream, and a tea together if you wanted.
Steeping. The recipes outlined are specifically designed to taste great freshly mixed. If you are making your own recipes and it doesn't taste great fresh, and it's more of a creamy and savory flavor, let it sit for a couple of weeks and then try it again. With the more creamy flavors, sometimes they need to "steep" in order to taste good. A couple famous steeping flavors are custards and ry4. They tend not to taste great out of the gate but given a little bit of time they develop into something else.
Trying flavors. When you are making new flavors you are going to come across the problem of how to try what you are making. The best and easiest way to do this is to get yourself a Rebuildable Dripping Atomizer, RDA. An RDA is basically a barebones tankless way to vape. You build your own coils out of kanthal wire, or stainless, and wick it with cotton. I won't go into any sort of detail on how to do this particular thing as there is a lot to it. But the reason why you want to do this for creating recipes is that you can immediately taste it and not have to worry about pouring it out or changing the coil. You can quickly burn out the flavor you have on the wick and try a new one. If all else fails and you still taste your previous flavor, then rewicking it isn't that big of a deal.
External info: https://www.reddit.com/r/DIY_eJuice/