Rayon wick, possible side effects and causes.

Monday, 11 August 2014  |  John

A number of vapers have said they have felt adverse effects after switching to Rayon and the focus has been on Rayon as the cause.
However, the general symptons have been mostly those associated with vaping too much, sore throat, wheezing, heavy chest,
which led me to look at it from a wider perspective. These are my observations, not definitive scientific tests.

I spent some years in th'owden days (1970s!) working in the textile industry for a company that used a wide range
of natural and synthetic material. It was when I revisited methods of Rayon manufacture that I had the 'light bulb moment'.
I remember studying material and colour technology and the description of Rayon is that it is a Filament yarn.
Cotton yarns are made by combing and spinning loose cotton fibres to make it into as uniform a strand as possible, which
means that although it looks like a thread, it is in fact many tiny pieces of cotton clinging together. It's natural properties
make it a good wicking material, but Rayon has a big advantage. Filament yarns are produced from a viscous liquid by forcing
it through a set of tiny holes called a Spinneret and binding it together as a continuous yarn. There are at least four extrusion/spinning
methods used on synthetic yarns, Rayon uses the oldest method, wet spinning. The Spinneret sits in a chemical bath and
as the filaments emerge from the bath they solidify. The result is a continuous yarn with a very uniform structure, as opposed
to cotton which is far from being continuous. The number/thickness of filaments in each yarn determines the Denier, or weight per length.

Rayon has a number of properties that make it a good candidate for coil wicks: the structure is uniform and tubular which allows easy
passage of liquid along it as the adhesion to the filament walls is stronger than the cohesive forces between the liquid molecules.
Rayon has a high absorbency level coupled with an efficient release level; it suspends liquid very well but does not cling to it excessively.
The Blue Foam has similar properties in terms of suspension/release but pore density is crucial, 45 pores per inch being ideal.

The bottom line is that Rayon will most likely wick liquids better than cotton, but that is possibly what is causing problems for some users.
I must default to the scientific position of 'we don't know yet', but it is possible that the Rayon is wicking so well that for some people and/or
in certain set-ups/devices it is delivering too much liquid for that individual which results in greater than normal quantities of vapour
(PG/VG/Nicotine/flavour) being delivered to the lungs and causing the symptoms that have been reported. There are several options that
might alleviate the symptoms; stop using Rayon (obvious!), reduce the efficiency of the device (power/airflow), reduce the Nicotine strength.

A scientific study on volume for volume comparison of how much is taken into the lungs with vaping v smoking might give some indication;
this is not a toxicity test as we know tobacco smoke is far worse, but I'm sure there are a lot of vapers who inhale far greater quantities per drag and/or inhale a greater daily quantity. There are contra indications, and although relatively mild on the whole, they still warrant investigation, along with more research on any potential adverse effects of using Rayon as wicking material. I would probably feel as safe using Rayon as any other common wick material, but whether it would lead to other problems I don't know.
What we do know is why Rayon makes a very efficient wick!

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Update: Dr Konstantinos Farsalinos has begun testing wick temperatures as part of his study on e-cigarettes/eliquid and their safety.
Hopefully he will be able to include Rayon in those tests as it is becoming popular with vapers.

 

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