Why Johnsons Creek clogs atomizers

[Bertrand]

DO NOT BE ALARMED. I AM NOT A CHEMIST. TAKE IT WITH A GRAIN OF SALT.

I think I've figured out what's happening to clog atomizers. Under the right conditions (I can't reliably replicate them) you can get "propylene glycol" e-liquid to polymerise in the presence of glycerine. It forms a kind of sludge that looks like what I've seen in pics of the 'bad' JC eyedroppers. I think the trouble with replcating this is that triggering radical polymerisation is a bit hit and miss.

I got this result, by the way, with pure glycerine (not the JC liquid) along with a different (non-JC) e-liquid. I am not sure why it would polymerise, but I do have a suspicion. I don't want to be alarmist: I am not a chemist, but it would be good to get one to figure out what's happening.

A precursor in one method of PG production is propylene oxide (according to the toxology report - known carcinogen, LC50 for inhalation in mice is 1740 ppm/4hr hehehe - let's hope I'm wrong.) In the presence of glycerine it can form a long chain polymer. (This is a well known reaction. Eg. Polypropylene glycol - Wikipedia, the free encyclopedia) I'm pretty sure JC have glycerine in their PG as well as NPG liquid, whereas the other supplier - same factory for the rest isn't it - doesn't. From what I can see, moving from PG back to PO is a little tricky so my guess is that some sources of PG have not been completely converted from PO, but as I said - I'm not a chemist. hehehe - take it with a grain of salt.

Does anyone know of another polymerisation reaction that might be occurring? BTW: this happened in the presence of stainless steel, covered by a white vinegar solution if you want to try it. (Was cleaning something with a bunch of different solutions in it the first time, and was curious what this stuff coming out was.) I could get it to occur a few times, but not reliably.

I might keep trying to find a replicable method, but I'm tempted just to stop using PG liquid entirely to be on the safe side. BUT DO NOT BE ALARMED. I would love for a chemist to clear this up.

[Schroedinger's cat]

Bertrand, if your hypothesis were correct, does it mean that we should not mix PG with VG as a general rule? I just did it today for the first time, because I received a bottle of liquid that was 24 mg instead of 18 mg (as I had ordered), and I did not want to use it at that strength. Also, I think that several here do their diy juice using VG and adding flavors, which, as a rule, have PG in them. I am not a chemist, either, so I hope someone who is will clear this up for us....

[Bertrand]

Bertrand, if your hypothesis were correct, does it mean that we should not mix PG with VG as a general rule? I just did it today for the first time, because I received a bottle of liquid that was 24 mg instead of 18 mg (as I had ordered), and I did not want to use it at that strength. Also, I think that several here do their diy juice using VG and adding flavors, which, as a rule, have PG in them. I am not a chemist, either, so I hope someone who is will clear this up for us....

So do I hehehehe. Look, I don't know what's really going on here, so I would suggest you continue what you're doing until we actually know.

All I really know is I could get some PG e-liquid to polymerize several times. I don't really know if it was the glycerine, the vinegar, the stainless steel, or a combination of them.

PS. I had it in an ultrasonic cleaner, but I don't think I needed to switch it on one of the times it did it. As I said, I haven't been able to reliably replicate this.

[Schroedinger's cat]

Yes, I will continue to cut my super-high liquid for sure, because otherwise I will get myself a nicotine overdose now, rather than maybe some cancer later. I mainly wanted to know about it to see whether I should expand my VG experiments to include flavors and such.... I really wish more producers other than JC made VG-based. Even though in the end I do not think that JC killed my atomizer (although it may have finished it), their liquid is so thin that I cannot really use it (I had the PG version). I put it in the cart, and then the thing is completely dry after 3 drags - and I have no idea where it's gone to....

[Bertrand]

By the way, I think a water & polypropylene oxide mixture would look the same as a water and propylene glycol mixture using some forms of spectroscopic analysis. (Chemical composition is the same, and in the same proportions.)

[Bertrand]

hmmm.. I think my slight concern just got upgraded to mild worry. I had a dig around for articles on propylene oxide residues in propylene glycol production, and found this (ironically from a book about smoking, specifically propylene glycol's use as a humectant):

"PG may thermically degrade to yield propylene oxide" and "Several commercial samples of PG ... already contained traces of propylene oxide."

Tobacco and Public Health: Science ... - Google Book Search p76

They were concerned about PG's 0.46 - 2.24% use in cigarettes, as opposed to the 60+% use in e-cigarettes.

As I stated below, testing the chemical composition alone would appear to be inadequate, since:

(1) xH2O + yC3H8O2 = (2x+8y)H (x+2y)O yC (propylene glycol + water)
(2) xH2O + yC3H6O = (2x+6y)H (x+y)O yC (propylene oxide + water)

Let x=1, y=1 for equation one, x=2, y=1 for equation 2 and we have:

10H 3O 1C (propylene glycol + water)
10H 3O 1C (propylene oxide + water)

See the problem?

I started looking into this thinking there would be an obvious polymerization involving PG and glycerine to explain the JC clogging up atomizers. Now it's beginning to like like an endorsement to only buy JC's NPG. It's a little worrying when you see this stuff turn into a goo, you squeeze the goo and it turns into nylon looking stuff. I should have kept some to take photos.

As I said, I'm not a chemist, so take it with a grain of salt.

[Schroedinger's cat]

Maybe you should start a thread in which a chemist's attention is especially called for.... I am afraid that VG-based liquids may not be the solution, either, if the flavors they add have PG in them.... Oh, well, cigarettes have more carcinogens, anyway. Although we may be getting quite a lot of a specific one, now, if you are correct.

I have so far only used PG-based liquids (except for the one I am cutting with VG now), and all my atomizers are alive and well after more than 60 days -so I doubt that I had a lot of polymerization going on, given that I clean them only occasionally, but this is sure something we need to find out.

[Bertrand]

No. That's the thing. I'm sure not all PG liquids are contaminated, but according to that book, it's quite common. This would explain why only some people have trouble with JC liquid: polymerization won't always occur, and not all the PG base will be contaminated. I've run out of the liquid I observed it with, otherwise I would have liked to send it for lab tests to confirm.

[Kate]

As far as I know, nobody has reported problems with the new recipe Johnson Creek, they seem to have solved their problem.

The problems they were having applied to both the pg and non pg formulas.

I'm concerned that this thread and it's title are misleading. This is no longer an issue with Johnson Creek and is a general health concern. Could you consider changing the title to something like 'polymerisation' or 'propylene oxide' and having it moved to the health board?

This is a very interesting thread, thanks for posting your findings Bertrand.

[Bertrand]

As far as I know, nobody has reported problems with the new recipe Johnson Creek, they seem to have solved their problem.

The problems they were having applied to both the pg and non pg formulas.

I'm concerned that this thread and it's title are misleading. This is no longer an issue with Johnson Creek and is a general health concern. Could you consider changing the title to something like 'polymerisation' or 'propylene oxide' and having it moved to the health board?

This is a very interesting thread, thanks for posting your findings Bertrand.

Yeah it's now a bit of both. If I'm right, it will still happen with the new liquid - depends on whether you mix it with some contaminated e-liquid, and whether JC gets a contaminated batch of PG. JC were mainly concerned with filtering, but from what I saw form in front of me it is a chemical reaction, not left over gunk, that clogs atomizers.