First up thanks dspin for the link. The Vape Mesh Company have just recently set-up I believe how-ever they have been in the mesh and wire industry for years so i suppose this is a logical branch out for them after the enquiries and sales of SS mesh for vaping they must have had recently (me included

)
Back on topic

My first delivery of 2.5mm 7/19 rope arrived today, I ordered from Ebay from a non vape related site (basically just searched and bought a meter to test). It was listed as 316 marine grade with a polished finish.
I cut small sections using a cut-off wheel on an angle grinder and unraveled one to check for nylon thread inserts.
None were found so I made a solution of hot (but not boiling) caustic soda in a beaker and added the sections of rope along with a few lengths of 316 welding rod.
The rope immediately reacted!!! Bubbles coming up all over and you could see the galvanising fizz away!! The welding rod sections remained perfectly inert with no reaction.
With-in an hour the rope had turned black. I have left this to continue overnight and am interested to see whats left in the morning

I contacted the seller and told them of my test and they remain adamant that they sent 316 marine grade ss. I don`t think so!!! but they did fully refund my money....Hmmmm.
I have three more samples/small sections coming from three more different sellers and will test each one! My hopes are that the samples I`ve bought from the marine type suppliers will be ok.
I`ll update when I`ve tested and in the meantime just a bit of info on the resistance of 316 and 304 to caustic soda......
Article: Selection of stainless steels for handling sodium hydroxide (NaOH)