“…This means that the Stokes law for the sedimentation rate, that states a dependence of the settling rate on the square of the particle radius, cannot be applied in our case. This can be mainly attributed to (i) a nonspherical shape of the particles, , (ii) the roughness and porosity of the particle surface, , and (iii) the high concentration of the dispersions 4 Behavior of the stability parameter ξ for dispersions of Ca(OH) 2 colloidal particles and microparticles in water and propan-1-ol: (a) colloidal particle/propan-1-ol, (b) microparticle/propan-1-ol, (c) colloidal particle/water, and (d) microparticle/water. 5 Example of application of Ca(OH) 2 platelike submicrometer crystals dispersed in propan-1-ol during the preconsolidation in the restoration of the wall paintings by Santi di Tito (16th century) Gli Angeli Musicanti on the Counterfaçade of the Santa Maria del Fiore Cathedral in Florence.…”
Section: Resultsmentioning
confidence: 99%
“…This means that the Stokes law for the sedimentation rate, that states a dependence of the settling rate on the square of the particle radius, 20 cannot be applied in our case. This can be mainly attributed to (i) a nonspherical shape of the particles, 20,21 (ii) the roughness and porosity of the particle surface, 22,23 and (iii) the high concentration of the dispersions. 24 Finally, the dispersions in propan-1-ol have been used to restore a degraded region of some 16th century wall paintings in the Cathedral of Florence.…”
We studied the synthesis and characterization of Ca(OH)2 colloidal particles and their application to
the restoration of wall paintings. Submicrometer Ca(OH)2 crystalline particles have been obtained by
mixing equal volumes of NaOH and CaCl2 aqueous solutions with different degrees of supersaturation
(from 2 to 10) and in the temperature range 60−90 °C. The Ca(OH)2 particles are crystalline and have
the appearance of hexagonal platelets with thicknesses of a few nanometers, as determined by scanning
electron microscopy, transmission electron microscopy, X-ray diffractometry, and atomic force microscopy
techniques. The kinetic stability of dispersions of Ca(OH)2 particles in water and propan-1-ol has also been
studied in view of their possible application in wall painting conservation. A successful example of this
application to the restoration of Santi di Tito's wall paintings (16th century) in the Santa Maria del Fiore
Cathedral in Florence is also reported.
“…This means that the Stokes law for the sedimentation rate, that states a dependence of the settling rate on the square of the particle radius, cannot be applied in our case. This can be mainly attributed to (i) a nonspherical shape of the particles, , (ii) the roughness and porosity of the particle surface, , and (iii) the high concentration of the dispersions 4 Behavior of the stability parameter ξ for dispersions of Ca(OH) 2 colloidal particles and microparticles in water and propan-1-ol: (a) colloidal particle/propan-1-ol, (b) microparticle/propan-1-ol, (c) colloidal particle/water, and (d) microparticle/water. 5 Example of application of Ca(OH) 2 platelike submicrometer crystals dispersed in propan-1-ol during the preconsolidation in the restoration of the wall paintings by Santi di Tito (16th century) Gli Angeli Musicanti on the Counterfaçade of the Santa Maria del Fiore Cathedral in Florence.…”
Section: Resultsmentioning
confidence: 99%
“…This means that the Stokes law for the sedimentation rate, that states a dependence of the settling rate on the square of the particle radius, 20 cannot be applied in our case. This can be mainly attributed to (i) a nonspherical shape of the particles, 20,21 (ii) the roughness and porosity of the particle surface, 22,23 and (iii) the high concentration of the dispersions. 24 Finally, the dispersions in propan-1-ol have been used to restore a degraded region of some 16th century wall paintings in the Cathedral of Florence.…”
We studied the synthesis and characterization of Ca(OH)2 colloidal particles and their application to
the restoration of wall paintings. Submicrometer Ca(OH)2 crystalline particles have been obtained by
mixing equal volumes of NaOH and CaCl2 aqueous solutions with different degrees of supersaturation
(from 2 to 10) and in the temperature range 60−90 °C. The Ca(OH)2 particles are crystalline and have
the appearance of hexagonal platelets with thicknesses of a few nanometers, as determined by scanning
electron microscopy, transmission electron microscopy, X-ray diffractometry, and atomic force microscopy
techniques. The kinetic stability of dispersions of Ca(OH)2 particles in water and propan-1-ol has also been
studied in view of their possible application in wall painting conservation. A successful example of this
application to the restoration of Santi di Tito's wall paintings (16th century) in the Santa Maria del Fiore
Cathedral in Florence is also reported.
“…For example, if the mean size of a number distribution by IA is subject to an error ± 2 %, after conversion the error will increase to ± 6 % error because the volume mean is a cubic function of diameter. I I I I I I I I I --I I I I I I I I I --I I I I I I I I I --I I I I I I I I I --I I I I I I I I --I I I I I I I I - (8) Technique error (%) = (Technique mean -Technique converted mean ) X100 /Technique mean (9) Where, Technique is one of UA, LD or IA.…”
Section: Comparison Between Different Techniquesmentioning
confidence: 99%
“…An understanding of both size and shape of crystals gives a way to avoid such behaviour. A number of papers dealing with particle shape and size using different techniques have been published [3][4][5][6][7][8][9][10][11][12]. However, discussion was focussed on inorganic particle shapes.…”
paper, the same phenomenon was observed with evolving polymorphs of L-glutamic acid crystals (a and b form), oxalic acid, sucrose and monosodium glutamate.
Two methods of measurement of the crystal size distribution of needle-shaped carystals are compared: direct measurement of a number of crystals on a microphotograph, which is rather tedious and time consuming, and the photosedimentometric method which is quicker, easy to perform but not so suitable for not isometric crystals. A method is described that brings results of both of these methods into agreement. The method has been verified on strongly anisometric particles of calcium sulphate.Es wurden zwei Methoden zur Bestimmung der KristallgroDenverteilung von nadelformigen Kristallen verglichen: Direkte Messung einer grooeren Anzahl von Kristallen an einer Mikrophotographie, was eine miihsame und zeitraubende Methode reprasentiert, und die photosedimentometrische Methode, die zwar bequemer und schneller ist, aber fur nicht isometrische Kristalle weniger geeignet. Es wird eine Methode beschrieben, die die Resultate beider erwahnten Methoden zusammenbringt. Diese Methode wurde an nadelformigen Kristallen von CaSO, erfolgreich gepriift.
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