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Looking for damage dose relations using metal sensors. Bart Ankersmit Simon Watts Virginia Costa. INTRODUCTION. Pollutant. Metal. Amount / Composition / Time ?. CORROSIVE ATMOSPHERES. Mimmic museum atmosphere: SO 2 / NO x / O 3 Organic acids (HAc / Formic Acid) / Formaldehyde
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Looking for damage dose relations using metal sensors Bart Ankersmit Simon Watts Virginia Costa
INTRODUCTION Pollutant Metal Amount / Composition / Time ?
CORROSIVE ATMOSPHERES • Mimmic museum atmosphere: • SO2 / NOx / O3 • Organic acids (HAc / Formic Acid) / Formaldehyde • Sulfides (H2S / OCS) • Concentrations: • Background levels • 10x higher (museum event) • 10x higher (lab concentrations)
Cu & Ag Tokens Composition of surface Onguard f (t, pollutants) Mass increase
Short term measurement Non-specific ‘natural aging’ Dutch archival law Present in some museums 12 provincial archives
Piezo Electric Crystal Frequency (Hz) Accept / not acceptable Å (t) ?
oven - H2S - SCO - HAc - HAc / FAc
Purafil: Extremely pure air Data against “background” air (22 oC / 50%)
SCO: copper more reactive than silver HAc + FAc: copper 2 reaction products ELECTRO CHEMICAL ANALYSIS OF COUPONS
Why? What can be done? Silver tarnishing
Deployment QMB Ventilation + Recirculation Recirculation
V+RC = 74 Å/yr Silver yellow in 2 years RC = 32 Å/yr Silver yellow in 5 years
CONCLUSIONS [Pollutants] reaction products f [Pollutants] is unclear QMB is not behaving the same way as the tokens Hanging issues
Open issues Uneven tarnishing / corrosion? Fequency drift? Δf ↔ ΔM ↔ degradation of mixed collection