why pg

[Scaevola]

Thanks for the quick replies, everyone! I am now on their website. If you click a bottle of liquid, you will see a drop-down menu for PG or non-PG. There is a small question mark next to this menu and clicking it will display this message:
"Here, you will choose whether you would like your selection made from our traditional PG formula or our new Non-PG formula. The primary ingredient in our Non-PG formula is high food-grade vegetable glycerin, a safe consumable compound used in many desserts and sauces. Our Non-PG formula typically produces a similar amount of vapor as our PG version."

[Wansbeck]

Atomized water rapidly evaporates at room temperature. This can be prevented by coating the droplets with a film of oil to give a longer lasting 'smoke'.
To avoid poisoning the audience, theatrical 'smoke' machines used to use food-safe glycerine for this purpose.
A major problem with glycerine was its slow and sticky breakdown leading to oily coatings on walls and furniture in areas of heavy use.
To avoid this problem smoke machine manufacturers now use PG which has quicker and cleaner breakdown characteristics.
The relatively low quantity of vapour from e-cigs should not cause a problem but maybe e-cig manufacturers are concerned that glycerine could clog the atomizer.

[Bertrand]

My apologies Bertrand, I've not seen where they say that.

Click the "?" next to the non-PG selection box on their website.

[rcross]

...
A major problem with glycerine was its slow and sticky breakdown leading to oily coatings on walls and furniture in areas of heavy use.
To avoid this problem smoke machine manufacturers now use PG which has quicker and cleaner breakdown characteristics.
The relatively low quantity of vapour from e-cigs should not cause a problem but maybe e-cig manufacturers are concerned that glycerine could clog the atomizer.

What about the "slow and sticky breakdown" in your lungs?

[robw]

That is my question as well. Am I replacing the tar with oil? Am I now coating my lungs with PG or VG? What is the chance I could drown in it?

[Wansbeck]

It has been several years since I checked out the safety of 'smoke' machines and convinced myself that they were safe enough to give my kids an occasional serious dose for parties etc.
I have had a quick look on the web and not been able to find a reference but from what I can remember the 'sticky mess' is glucose syrup or similar.
Again as far as I can remember, there are no toxic substances produced by room temperature breakdown.
My major concern is what is produced when the atomizer overheats as almost everyone has experienced this.
Glycerine and PG are common ingredients in tobacco so we get some burnt through normal smoking but as some Greek guy said hundreds of years ago "the poison is in the dose".

[Wansbeck]

“some Greek guy said hundreds of years ago”

I had a memory once but years of alcohol and tobacco have taken their toll.

I'm back from the pub now, where I'm allowed to vape, and thought I'd better check this out.
From ingentaconnect.com/content/resinf/opm/2006/00000017/00000001/art00010
I got this:

“Recent anthrax scares have focused our fears on toxic substances and the dangers they pose. But as the Swiss physician Paracelsus noted more than 400 years ago: "All things are poison and nothing is without poison. It is the dose only that makes a thing not a poison."

Paracelsus, regarded by many as the father of toxicology, is often paraphrased to have said that the poison is in the dose ["Alle Ding sind Gifft und nichts ohn Gifft. Allein die Dosis macht das ein Ding kein Gifft ist." (All things are poison and are not poison; only the dose makes a thing not a poison)]. With this statement, Paracelsus considered the apparent safety of toxicants at low doses. Moreover, some substances, although toxic at higher doses, can be stimulatory or even beneficial at low doses. This is the case with compounds such as pharmaceuticals that are used for their beneficial effects, as well as with compounds such as pesticides that are normally used as toxicants. This stimulatory effect of a low dose of a toxicant is called hormesis. Although this phenomenon was recognized earlier, the term hormesis was first used by Southam and Erlich (1943) to describe the effect of an oak bark compound that promoted fungal growth at low doses, but strongly inhibited it at higher doses. They coined this term using the Greek word "hormo" (to excite), the same root used in the word hormone. “

In my defence, Paracelsus sounds Greek to me!

[TropicalBob]

And you're right about glycerine breaking down to glucose -- which is the same stuff they'll drip directly into a vein in your arm after you overdose on nicotine from 36mg liquid and have to be rushed by ambulance to the emergency room.

[Wansbeck]

Thanks Bob, I must have a few memory cells still working