scholarly journals Back protection of canvas paintings

2020 ◽  
Author(s):  
Tim Padfield ◽  
Nicolas Padfield ◽  
Daniel Sang-Hoon Lee ◽  
Anne Thøgersen ◽  
Astrid Valbjørn Nielsen ◽  
...  
Keyword(s):  
Temperature Variation ◽  
Room Temperature ◽  
Alloy Sheet ◽  
Strong Variation ◽  
Constant Wall Temperature ◽  
Moisture Exchange ◽  
Wooden Frame ◽  
Back Plate ◽  
Inner Surface ◽  
Painting On Canvas

Abstract A painting on canvas, stretched on a wooden frame, was fitted with various styles of back protection and then exposed to a cycle of temperature variation at the back, with the front exposed to a constant room temperature. The painting was also exposed to a constant wall temperature and varying room temperature. The space between the canvas and the back board was fitted with temperature and relative humidity (RH) sensors. The unprotected painting suffered a large RH variation at its back, because of the varying canvas temperature interacting with the constant room air moisture content. Effective stabilisation of the RH behind the canvas against temperature variation was provided by a shiny aluminium alloy sheet sealed against the frame. The non-absorbent back board experienced a strong variation in RH, because of humidity buffering of the space by the painting canvas at a different temperature. Either a space or insulation between this back plate and the wall reduced the risk of condensation on the inner surface of the back plate. Insulation will however increase the risk of condensation on the wall surface behind the painting. An absorbent back board de-stabilised the RH at the painting canvas surface by providing a competing humidity buffer at a different temperature. To provide protection against moisture exchange with an unsuitable room RH, extra humidity buffer was placed 3 mm behind the painting canvas, kept close to the painting temperature by insulation between this buffer and the back board. This stabilised RH at the canvas surface but increased both the temperature and the RH variation at the back board and thus increased the risk of condensation on the inner surface of the back board. The RH and the temperature in the narrow spaces between the painting canvas and the wooden stretcher frame were always more nearly constant than in the open canvas area, which suggests an explanation for the widely observed better condition of the areas of canvas paintings which lie close over the support structure. Our conclusion is that a non-absorbent, impermeable back plate gives good RH stability against a changing temperature gradient between wall and painting surface.

scholarly journals Back protection of canvas paintings

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Tim Padfield ◽  
Nicolas Padfield ◽  
Daniel Sang-Hoon Lee ◽  
Anne Thøgersen ◽  
Astrid Valbjørn Nielsen ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Relative Humidity ◽  
Temperature Variation ◽  
Room Temperature ◽  
Single Point ◽  
Confined Space ◽  
Constant Wall Temperature ◽  
Back Plate ◽  
Inner Surface

Abstract In this paper different scenarios for back protection of a canvas painting and their effect on the stability of the relative humidity behind the painting are tested. A painting on canvas, stretched on a wooden frame, was fitted with various styles of back protection and then exposed to a cycle of temperature variation at the back, with the front exposed to a constant room temperature. The painting was also exposed to a constant wall temperature and varying room temperature. The space between the canvas and the back board was fitted with temperature and relative humidity (RH) sensors. The sensors were used to provide the essential single-point data of temperature and RH at the given locations. For more comprehensive understanding of the rather confined space, further numerical simulation (computational fluid dynamics) was adopted as part of the investigation. The computational fluid dynamics was used to understand the natural convection within the microclimate through the depictions of temperature distribution, as well as the corresponding airflow. The unprotected painting suffered a large RH variation at its back, because of the varying canvas temperature interacting with the constant room air moisture content. Effective stabilisation of the RH behind the canvas against temperature variation was provided by a shiny aluminium alloy sheet sealed against the frame. The non-absorbent back board experienced a strong variation in RH, because of humidity buffering of the space by the painting canvas at a different temperature. Either a space or insulation between this back plate and the wall reduced the risk of condensation on the inner surface of the back plate. Insulation will however increase the risk of condensation on the wall surface behind the painting. An absorbent back board de-stabilised the RH at the painting canvas surface by providing a competing humidity buffer at a different temperature. To provide protection against moisture exchange with an unsuitable room RH, extra humidity buffer was placed 3 mm behind the painting canvas, kept close to the painting temperature by insulation between this buffer and the back board. This stabilised RH at the canvas surface but increased both the temperature and the RH variation at the back board and thus increased the risk of condensation on the inner surface of the back board. The RH and the temperature in the narrow spaces between the painting canvas and the wooden stretcher frame were always more nearly constant than in the open canvas area, which suggests an explanation for the widely observed better condition of the areas of canvas paintings which lie close over the support structure. Our conclusion is that a non-absorbent, impermeable back plate gives good RH stability against a changing temperature gradient between wall and canvas painting surface.

scholarly journals Back protection of canvas paintings

2020 ◽  
Author(s):  
Tim Padfield ◽  
Nicolas Padfield ◽  
Daniel Sang-Hoon Lee ◽  
Anne Thøgersen ◽  
Astrid Valbjørn Nielsen ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Relative Humidity ◽  
Temperature Variation ◽  
Room Temperature ◽  
Single Point ◽  
Confined Space ◽  
Constant Wall Temperature ◽  
Back Plate ◽  
Inner Surface

Abstract In this paper different scenarios for back protection of a canvas painting and their effect on the stability of the relative humidity behind the painting are tested. A painting on canvas, stretched on a wooden frame, was fitted with various styles of back protection and then exposed to a cycle of temperature variation at the back, with the front exposed to a constant room temperature. The painting was also exposed to a constant wall temperature and varying room temperature. The space between the canvas and the back board was fitted with temperature and relative humidity (RH) sensors. The sensors were used to provide the essential single-point data of temperature and RH at the given locations. For more comprehensive understanding of the rather confined space, further numerical simulation (computational fluid dynamics) was adopted as part of the investigation. The computational fluid dynamics was used to understand the natural convection within the microclimate through the depictions of temperature distribution, as well as the corresponding air flow. The unprotected painting sffered a large RH variation at its back, because of the varying canvas temperature interacting with the constant room air moisture content. Effective stabilisation of the RH behind the canvas against temperature variation was provided by a shiny aluminium alloy sheet sealed against the frame. The non-absorbent back board experienced a strong variation in RH, because of humidity bu ering of the space by the painting canvas at a different temperature. Either a space or insulation between this back plate and the wall reduced the risk of condensation on the inner surface of the back plate. Insulation will however increase the risk of condensation on the wall surface behind the painting. An absorbent back board de-stabilised the RH at the painting canvas surface by providing a competing humidity bu er at a different temperature. To provide protection against moisture exchange with an unsuitable room RH, extra humidity bu er was placed 3 mm behind the painting canvas, kept close to the painting temperature by insulation between this bu er and the back board. This stabilised RH at the canvas surface but increased both the temperature and the RH variation at the back board and thus increased the risk of condensation on the inner surface of the back board. The RH and the temperature in the narrow spaces between the painting canvas and the wooden stretcher frame were always more nearly constant than in the open canvas area, which suggests an explanation for the widely observed better condition of the areas of canvas paintings which lie close over the support structure. Our conclusion is that a non-absorbent, impermeable back plate gives good RH stability against a changing temperature gradient between wall and canvas painting surface.

Structural and electrical properties of KCa2Nb5O15 ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Banarji Behera ◽  
Pratibindhya Nayak ◽  
Ram Choudhary
Keyword(s):  
Electrical Properties ◽  
Temperature Variation ◽  
Electrical Transport ◽  
Room Temperature ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Transport Processes ◽  
Relaxation Processes ◽  
Orthorhombic Crystal Structure ◽  
Grain Distribution

AbstractA polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

Anomalous effect of grain size on the room-temperature bendability of Mg–Gd alloy sheet

2021 ◽  
pp. 142397
Author(s):  
Chao He ◽  
Ming Yuan ◽  
Bin Jiang ◽  
Lintao Liu ◽  
Qinghang Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Alloy Sheet ◽  
Anomalous Effect

Texture of AZ31 Magnesium Alloy Sheet Heavily Rolled by High Speed Warm Rolling

2007 ◽  
Vol 539-543 ◽  
pp. 3359-3364 ◽  
Author(s):  
Tetsuo Sakai ◽  
Hiroshi Utsunomiya ◽  
H. Koh ◽  
S. Minamiguchi
Keyword(s):  
Magnesium Alloy ◽  
High Speed ◽  
Room Temperature ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Az31 Magnesium Alloy ◽  
Basal Texture ◽  
Double Peak ◽  
Magnesium Alloy Sheet ◽  
Az31 Magnesium Alloy Sheet

Magnesium alloy sheets had to be rolled at elevated temperature to avoid cracking. The poor workability of magnesium alloy is ascribed to its hcp crystallography and insufficient activation of independent slip systems. Present authors have succeeded in 1-pass heavy rolling of AZ31 magnesium alloy sheet below 473K by raising rolling speed above 1000m/min. Heavy reduction larger than 60% can be applied by 1-pass high speed rolling even at room temperature. The improvement of workability at lower rolling temperature is due to temperature rise by plastic working. The texture of heavily rolled AZ31 magnesium alloy sheet is investigated in the present study. The texture of sheets rolled 60% at room temperature was <0001>//ND basal texture. At the rolling temperature above 373K, the peak of (0001) pole tilted ±10-15 deg toward RD direction around TD axisto form a double peak texture. The texture varied through thickness. At the surface, the (0001) peak tilted ±10-15 deg toward TD direction around RD axis to form a TD-split double peak texture. The direction of (0001) peak splitting rotated 90 deg from the surface to the center of thickness. Heavily rolled magnesium alloy sheets have non-basal texture. The sheets having non-basal texture are expected to show better ductility than sheets with basal texture.

scholarly journals Effect of Cold Rolling and Heat Treatment on the Mechanical Properties of GH4169 Alloy Sheet at Room Temperature

Metals ◽  
2015 ◽  
Vol 6 (1) ◽  
pp. 1 ◽  
Author(s):  
Shi-Hong Zhang ◽  
Neng-Yong Ye ◽  
Ming Cheng ◽  
Hong-Wu Song ◽  
Hong-Wei Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cold Rolling ◽  
Room Temperature ◽  
Alloy Sheet ◽  
Gh4169 Alloy

Temperature induced phase transition in fluorescence active zein nanoparticles

2021 ◽  
Vol 99 (1) ◽  
pp. 18-23
Author(s):  
Charlie Joe Croxford ◽  
Rajpreet Kaur ◽  
Kultar Singh ◽  
Mandeep Singh Bakshi
Keyword(s):  
Phase Transition ◽  
Temperature Variation ◽  
Room Temperature ◽  
Colloidal Stability ◽  
Precipitation Method ◽  
Effect Of Temperature ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Potential Use ◽  
Controlled Precipitation

Stable colloidal zein nanoparticles (NPs) were synthesized by using controlled precipitation method. They were made fluorescence active by incorporating a small amount of fluorescence quinolinium surfactant. The incorporation of fluorescence surfactant provided both the colloidal stability and the fluorescence ability to determine the phase transition in zein NPs under the effect of temperature variation. Maintaining colloidal stability under the effect of temperature variation is an essential aspect of zein NPs applicability as a source of vegetarian protein supplement in different food suspensions. Different techniques such as fluorescence, DLS size, zeta potential, and FTIR measurements were applied to determine the influence of temperature on the colloidal stability of zein NPs. Zein NPs undergo phase transition well above room temperature while maintaining their size in nanometer range, and the phase transition temperature decreased with the amount of zein used in the synthesis of zein NPs. The results highlighted the potential use of zein NPs as a vegetarian supplement protein in different food products.

Influence of Pressure Amplitude on Formability in Pulsating Hydro-Bugling of AZ31B Magnesium Alloy Sheet

2011 ◽  
Vol 128-129 ◽  
pp. 397-402
Author(s):  
Lian Fa Yang ◽  
Liang Yi ◽  
Chen Guo
Keyword(s):  
Magnesium Alloy ◽  
Wall Thickness ◽  
Room Temperature ◽  
Alloy Sheet ◽  
Pressure Amplitude ◽  
Excellent Performance ◽  
Az31b Magnesium Alloy ◽  
Stress Components ◽  
Uniform Expansion ◽  
Az31b Magnesium Alloy Sheet

The formability of the magnesium alloy sheets is poor at room temperature even though the magnesium alloy sheets are attractive because of their excellent characteristics. Application of pulsating hydroforming is a new and effective method to improve the formability. The effects of the pressure amplitude on the maximum bulging height and minimum wall thickness of the formed parts of AZ31B magnesium alloy sheets are examined using finite element simulations. It is shown that the distribution of maximum bugling height and minimum wall thickness is similar for different pressure amplitude A, and a uniform expansion in bulging region is obtained, the cause of the uniform expansion obtained may be caused by the variation of stress components. The AZ31B sheet has an excellent performance in formability when the pressure amplitude and pulsating frequency are properly selected.

Controlled Synthesis of PbWO4 Crystals with Good Fluorescence Property by a Novel Duck Egg Membrane

2015 ◽  
Vol 33 ◽  
pp. 49-59
Author(s):  
Bao You Gong ◽  
Le Pan ◽  
Qing Feng Zhang ◽  
Hui Zhang ◽  
An Jian Xie ◽  
...  
Keyword(s):  
Outer Surface ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Blue Shift ◽  
Biomimetic Synthesis ◽  
Reactant Concentration ◽  
Inner Surface ◽  
Egg Membrane ◽  
Duck Egg ◽  
Slight Blue Shift

PbWO4 crystals with different morphologies were readily induced by duck egg membrane via biomimetic synthesis at room temperature. The size and morphologies of the PbWO4 crystals could be controlled by outer or inner surface of duck egg membrane, the reactant concentration and the reaction time. The results show that spherical, flower-like and spindle-like crystals were obtained on the inner surface of membrane while rhombic, hexagon-like and chrysanthemum-like crystals were gained on the outer surface with the concentration of Pb2+ and WO42- increases. Room-temperature fluorescence spectra indicate the products on the inner surface of the duck egg membrane have a slight blue shift compared to that on the outer surface at the same condition. The PbWO4 crystals with small size obtained at a lower reactant concentration present a better fluorescence performance. The exploration of the reaction mechanism reveals that the interaction between Pb2+ ions and the proteins on the surface of duck egg membrane can make the conformation of the proteins more ordered. In general, the present synthesis route may be extended to prepare other inorganic functional micro-materials.

Sign in / Sign up

Export Citation Format

Share Document