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Distance from the Sea ….Extra

This note was posted to the Titanium Bolting FB Group 27 January 2020

I promise this is the last “distance from the sea” post ….. for a little while at any rate

I say extra, because here I’m talking about Heuco Wall (just 50m beyond Low Tide Wall), and this is one of a number of tests sites chosen for the long term UIAA corrosion studies.

Back in Jan 2014 Martin Roberts put in a whole bunch of different anchors arranged in 6 clusters. Three where in a small cave, open at both ends, and just above high tide level. The other three were on a high overhanging wall set some 20m in through the jungle.

Thus, now 6 years on, we are in a position to see if there is is any correlation between wall chemistry and anchor type.

This was also the site where the wall chemistry project began when in Dec 2016, Martin took some of the first measurements for me using a tweaked aquarium test kit. It immediately became obvious that the chemistry was not that which everybody was assuming.

It wasn’t until Dec 2018 that Stephen Gladieux grabbed some wall wash samples from there for me to do a complete electrolyte analysis.

This trip I have done a heap of spot tests to confirm the 4 complete analyses from a year ago.

Custers #2, #3 & #4 are inside the cave. Clusters #5, #6 & #7 are on the wall back behind the jungle. I can vouch it remains 100% dry given I was there in a downpour.

All samples taken from the clusters within the cave show high sulphate levels. All samples taken from the back wall in the jungle show zero or trace levels.

I took samples from just outside the cave, and from large blocks close to sea level and found no sulphate.

As I mentioned in a previous post, I suspect that the appearance of sulphate requires more than the availability of elemental sulphur from the marine aerosol, but also a suitable environment to support the growth of sulphur oxidisers, maybe in soils on the clifftop. This would explain why we tend to see either heaps of sulphate or none.

I’ll take a look at the complete electrolyte profiles and the corrosion we are seeing at this site in another post.

Cluster #2

Cluster #4
Cluster #5
Cluster #6
Cluster #7

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