I mentioned using this previously and was asked to make sure I provided a review. It's been many months now and I keep forgetting to do so... finally getting around to it.
For reference, in case you haven't heard of PDO... It's short for 1,3 Propanediol. Same chemical elements as PG, but different molecular arrangement. Currently more expensive than PG. So why use it? Early studies show significantly few people have PDO sensitivity than PG sensitivity. Since I'm one of those people with PG sensitivity... this seemed worth a shot to thin out my juices.
The one limitation to my feedback is that I can't do a side by side comparison with PG using otherwise the same recipe. (I don't even buy PG aside whats in the flavours themselves.)
As a flavour carrier
No question that it is a better flavour carrier than VG. I've tried numerous recipes as both Max VG, 80VG, and 70VG... with PDO taking the place of any PG that would normally be added after flavours to reach those numbers. In all cases, just as you'd expect with PG, the flavour is more pronounced the lower the VG content.
Viscosity
While this is far from scientific, the viscosity seems to be very similar to PG. I'm basing this entirely on how it drips compared to PG based flavourings.
Impact on wicking
Hasn't been a particularly cold winter here (yet, knock wood), but definitely wicks better in colder temperatures. A max VG juice knocked one of my tanks out of commission after I accidentally left it in the car. The other tank, which had a 70/30 was good to go.
Throat Hit - Saved the Biggest for Last
There is 1 juice that I still vape (that I buy) that contains PG. I always keep a higher nic juice on hand for when I'm traveling, or when I won't find time to go blow clouds somewhere. When I vape this way it's MTL. And since I have yet to find an MTL tank that handles high VG juice particularly well... the juice I buy is 60/40, 12mg nic. I haven't had (or so I thought) a reaction to this juice which I had assumed was because of how little of it I actually vape. The throat hit was quite high, but its what I would expect from a juice with that much nicotine.
A few weeks ago, for the first time since I started DIY, I made my own 12mg nic juice instead of buying the usual. I mixed a recipe I'm familiar with... but at 60/40, again using PDO instead of PG beyond flavourings.
The flavour was fantastic... but the throat hit was almost completely gone. In fact, just to convince myself I wasn't imagining things... I took a few direct lung hits... something I have never done without instantly triggering a coughing fit.
Don't get me wrong, 12mg nic has a throat hit all by itself. But compared to any other juice I've ever vaped at this high nic, the PDO was significantly smoother. This may be something even those of you who aren't worried about PG sensitivity may want to explore!)
Almost forgot to mention... in case it wasn't obvious by how much PDO I'm using and how many months I've been using it. I have had no reaction to PDO. I'm able to drip it onto my wrist directly and no reaction. By contrast, dripping a 70VG/30PG juice onto my wrist gave me a red mark.
Edit: Fixed typo in top section.
Thank you ZorroElite.
Have you noticed anything like the eliquid unsteeping after remaining in the PDO solution for a few months?
So far, the longest I've had juice steeping with PDO in it was about 1 month... and the recipe was one I typically only need to steep overnight. The flavour was pretty much exactly what I'd have expected.
I have heard the same rumour, but since I only make juice for myself and rarely does it last that long I didn't bother to try and test that specifically. (Having juice made a month prior was a total fluke!)
With my limited experience with PDO, I found a longer aging/blending time was needed. I performed a few tests with PDO side by side with PG, and initially the PDO mix was way off compared to the PG mix. It seemed to take a few weeks for the PDO mix to 'catch up' with the PG mix.