FLO Vanessa Oakden in a blog full of exclamation marks informs 'members of the public' of 'The Dangers of Olive Oil!' (15th February 2017). The problem is that metal finds are being ‘treated’ with olive oil by their collectors. She reckons the darkening of the 'patina' makes the archaeologist's job difficult:
for finds which are difficult to date, due to being in use throughout several periods, this obscuring of the natural patina makes dating the object considerably more difficult. [it causes] [...] difficulties dating some objectsI really do not follow this argument, probably it makes more sense if you're a metal detectorist. But 'there is a more serious reason why you should put the olive oil down'
Here is the science bit! Conservator Pieta Greaves of drakonheritage.co.uk explains: The main problem with olive oil is that it is a fat, it is effected (sic) by oxygen and light so degrades quickly if just left around. Essentially people are exposing objects to something than begins to rot and goes rancid inside the object. It also is likely to contain sulphur which actively attacks metals in particular. It is not reversible as a treatment and will in the end destroy the object.The main problem is that it in itself contains organic acids, as pointed out on this blog a while back.
UPDATE 16th Feb 2017'What happens to dugups when collectors get their hands on them' PACHI Tuesday, 7 July 2009'Apparently, "Collectors care for, study and preserve artefacts"...' PACHI Saturday, 6 March 2010'Metal Detecting Under the Microscope: "Preserving" finds in Olive Oil - Don't' PACHI Sunday, 30 September 2012'Portable Antiquity "Conservation" and Curation: UK Tekkie Style' but also 'Fifteen Million Quid Outreach - Effects' and 'Cleaning Smuggled Coins by CCCE' PACHI Wednesday, 6 February 2013'UK Metal Detecting: Olive Oil Again' PACHI Tuesday, 23 June 2015 ('Without a proper PAS to guide them, we'll be seeing from now on more and more of this sort of thing from UK metal detectors: 'Does Olive oil work? THE TEST' (by Addicted to bleeps » Sun Jun 21, 2015)...''Focus on Metal Detecting Gatekeeper Rodgers' PACHI Saturday, 27 June 2015"Preserving the past" UK Detectorist Style PACHI Saturday, 29 August 2015
and now FLO Vanessa Oakden has blocked a member of her public (me) from seeing her twitter account. No, please come over here Ms Oakeden and explain why you wrote what you wrote instead of running away like a frightened schoolgirl. Cat got your tongue when faced with questions from somebody whose not a thugwit detectorist or impressed by you posting 'heart shaped objects for Valentine's Day'? Shame on you woman, that is supposed to be 'archaeological outreach'? Pathetic, the lot of you.