I searched this sub for info on the differences but couldn't find anything noteworthy. Has anyone looked into this? I know 99.5% is fine but if 99.7% is somehow better I could make efforts to only buy the latter. What do you guys think?
I don't think it matters at all. I'm a pharmaceutical chemist, and you're talking about a 0.2% difference. This comes out to be 0.01 ml of water in a 5 cc tank, or the equivalent of 1/5 of a drop of water. (Since glycerin is hygroscopic I imagine it's unavoidable, and that 99.7% VG was only that percentage at manufacture, and not when you opened the bottle in your house )
I've used both and frankly never noticed a difference. As long as it's USP grade, it's as safe as you'll get. Like a lot of people, I've switched to Essential Depot VG: minimum 99.7% pure, USP grade, reasonably priced, good stuff. I just got a gallon a few weeks back, it was about $25 shipped from their Amazon store. I've also used Nude and TFA's VG in the past and they were fine too.
Can confirm, Essential Depot VG is good stuff. Now I just need to start using some non-oxidized nicotine.
Here's how I've always dealt with my nic: I keep the main bottle in my freezer, but pour a smaller amount out into an amber bottle for mixing. This "working" bottle generally lasts me a month or two before I need to refill it, but that means I only have to take my main bottle out of the freezer once ever few weeks instead of once a week (or however often I mix.) That way, even if the "working" bottle starts oxidizing, you're not wasting a bunch and you can get through all of it before it becomes unvapable anyway.
Besides that, you can also dilute the "working" bottle to make it a bit less hazardous in case you spill it. I buy 100mg/ml nic, but my working bottle is diluted down to 60mg/ml. The dilution ratio is personal preference, just keep it above whatever your normal nic level is.
I don't keep my working bottle in the freezer, although you certainly can. I find I go through it fast enough that keeping it in a dark cupboard is sufficient.
What's the deal with oxidized nic?
Oxidation of nicotine occurs in the presence of oxygen. Heat and light are also contributing factors to the degradation of nicotine. When oxidized, a normally pinkish nicotine solution will take on a brown to dark brown tinge depending on how far along it is in the oxidation process. Typically it will also take on a peppery smell, taste, and become very harsh when vaped. So it's always best to store your nicotine properly, and in a manner similar to how /u/catdumpling laid out above so to mitigate the chances of any of these nasty things happening to your store of nicotine.
the 0.2% difference is probably water. I go with the higher one where I can, seems to make sense to me to get it as pure as I can.
Water in juice is my least favorite thing about vaping. It makes a wet hit with no flavor, and I think it also makes my Kennedy RDA "leak" out the bottom.
It's usually only awful if I'm running below 30Watts because I'm chain hitting it, too. It just slows the process down.
I know it's water because when I vape outside in high humidity it does the same exact thing.
It's all the same. Higher than 99.5% is just marketing, as in it doesn't exist.
That's not true. If a company is having their batches lab tested, they'll have results that show what the purity of a given batch actually is. There is absolutely 99.7% purity VG and it's not just marketing (as long as the company is a reputable brand who handles their chemicals properly, at least.) If this wasn't the case, the reputable brands wouldn't bother putting batch and lot numbers on their bottles.
If the price difference isn't too great, I would go with whatever is higher purity. The extra "stuff" could be anything from the manufacturing process, but apparently 99.5 (or whatever USP requires) is considered safe enough for use in pharmaceuticals, which might be consumed in any number of ways. I'm guessing the manufacturing process doesn't use anything dangerous at low concentrations or 99.5 wouldn't be good enough.
Edit: Just checked out Wikipedia, ~~apparently VG is a byproduct of the production of biodiesel. In this form it's super full of extra garbage organic compounds. Repeated distillation is used to get the required purity, so yeah I would go with the higher purity, because that extra stuff is probably NOT water.~~
And I can't read. There are in fact other methods to derive VG, and others aren't as dirty, so water may in fact make up that small fraction of a percent.
> that extra stuff is probably NOT water.
Essential Depot Vegetable Glycerin is distilled from SOY or PALM products and each meet a minimum purity specification of 99.7+%. The 0.3% remainder is usually water as glycerin readily absorbs moisture from the air which is difficult to completely remove during the distillation process.
VG isn't always made from biodiesel production. There are a couple different methods, as well as a couple different sources (palm, soy, etc.)