Spara och bevara* bibliographic database

Camuffo, D (1991) Wall temperature and the soiling of murals. Museum Management and Curatorship, 10 (4). pp. 373-383. ISSN 02604779

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A balance is made here of the intensities of the main deposition mechanisms (i.e. Brownian diffusion, thermophoresis, inertial impaction, gravitational settling and Stefan flow) in the case of vertical wall surfaces, and thus frescoes or other murals. When the wall is colder than the air, the temperature gradient forces negative thermophoresis and develops a downward free-convection layer. This generates inertial impaction and increases gravitational settling. A further contribution due to the Stefan flow may be generated. When the wall is warmer, thermophoresis partially counteracts other deposition mechanisms for fine particles, but the temperature gradient generates an uprising flow, and inertial impaction of the largest particles occurs. The deposition rate is reduced for fine particles, but increased for the largest ones. As the mass of the suspended paniculate matter is concentrated in the coarsest particles, the net effect is a heavy soiling. Up-rising flows transport upwards the majority of particles, causing soiling also of the ‘downward facing’ parts of the surface irregularities. Warm floor or cold ceiling may cause atmospheric instability and convective motions, with the above mentioned negative effects. Cold floor and warm ceiling form stable temperature profiles and attenuation of turbulence. Under the warm ceiling a cushion of stable air forms without motion (and inertial deposition) and with thermophoresis (partially) counteracting Brownian diffusion. The best situation appears to be offered by cold floor, warm ceiling, walls in thermal equilibrium with ambient air, and air with stable temperature gradient.

Item Type: Article
Uncontrolled Keywords: Soiling; Wall paintings; Fresco; Temperature
Subjects: ?? climcon ??
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English > Damage functions > Soiling
Depositing User: Anna Samuelsson
Date Deposited: 30 Apr 2008 08:58
Last Modified: 04 Apr 2017 10:41

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