Salt, Dust and RH Risks in Coastal and Inland Areas David Thickett Collections Management Team.

Salt, Dust and RHSalt, Dust and RHRisks in Coastal and Inland AreasRisks in Coastal and Inland Areas

David ThickettDavid Thickett

Collections Management Collections Management TeamTeam

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Tem

per

atu

re in

°C

0102030405060708090100

Rel

ativ

e H

um

idit

y in

%

Telephone ExchangeTelephone Exchange

TelephonTelephonee

RepeaterRepeater

% surface coverage% surface coverage 1414 8181

weight loss weight loss ((mg/cmmg/cm22))

0.10.1 0.90.9

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2

4

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10

12co

vera

ge /

# pa

rticl

es (%

/ x1

00)

% coverage

# particles

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sodium magnesium sulphate chloride

Ion

Dep

osit

ion

Rat

e (µ

g/m

2 /day

)

TelephoneRepeater

Airborne DustAirborne Dust

0100020003000400050006000700080009000

10000

1.00 1.50 2.00 2.50 3.00

time (days)

# p

arti

cles

>0.75μm

>1.0μm

>2.0μm

>3.5μm

>5.0μm

>7.5μm

>10.0μm

>15.0μm

Surface wetness sensorSurface wetness sensor

Surface wetness resultsSurface wetness results

Critical RH = 53%

Repeater = 50%

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T/R

H (

°C/%

)

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resi

stan

ce (

Ω)

temp

RH

resistance

40 45 50 55 60 65 70 75 80 85 90

clean

XP

salt

salt+XP

RH (%)

54

63

78

81

ShieldShield UntreatedUntreated

TelephoneTelephone 0.001 (99.0%)0.001 (99.0%) 0.1060.106

RepeaterRepeater 0.018 (98.1%)0.018 (98.1%) 0.9340.934

Environment Under TyvekEnvironment Under Tyvek

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RH

(%)

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Tem

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ture

(ºC

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Room RH Tyvek RH

Tyvek T

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3000000

15/09/200400:00

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30/09/200400:00

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Re

sis

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ce

(Ω

)<

We

t

D

ry > Tyvek

Desk

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(µg/

m2 /d

ay)

inner case 1 case 2 outer case 3

Chloride Deposition RateChloride Deposition Rate(30 days)(30 days)

(µg/

m2 /

day)

Case Fabric Chloride Case Fabric Chloride

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chlo

rid

e (μ

g)

case 1 case 2 case 3

-40 -20 0 20 40 60 80 100

geothiteakaganeitemagnetiteiron

2.12%[Cl] = 0.19%

FeO0.833(OH)1.167Cl0.167 ~ 6.9%ClStahl, Corr. Sci, 2003

β-FeOOH6-12%Cl —> α-FeOOH<0.7%Cl

Thickett, proceedings of IRUG6, in press

Surface AnalysisSurface Analysissilver coupons 30 dayssilver coupons 30 days

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0.20.25

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incr

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in b

*

sulphidechloride

Thickett, Hallett, Bradley and LeeHildesheim, in press

Chloride SourcesChloride Sources

GaseousGaseous DustDust HandlingHandling UseUse Conservation TreatmentsConservation Treatments Post excavation cleaning (coins)Post excavation cleaning (coins)

Anion Deposition RateAnion Deposition Rate

0

20

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120

140

160

180

fashion death Roman Guy's 18thCentury

case

ion

de

po

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ion

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(ug

/m2/d

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)

chloride

sulphate

0

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40

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60

0 0.5 1 1.5 2 2.5

AER (/day)

Am

ount

of

Dus

t In

gres

sing

(%

)

Werner Collection Cases Werner Collection Cases at Ranger’s House at Ranger’s House

y = -0.31x + 8.6582

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7.6

7.8

8

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days

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(day-1

)

AcknowledgementsAcknowledgements

University College London University College London Centre for Sustainable Heritage (Bartlett Centre for Sustainable Heritage (Bartlett

School of Architecture)School of Architecture) Department of GeologyDepartment of Geology

Royal Historic PalacesRoyal Historic Palaces Museum of LondonMuseum of London