pigmented colorants: dependence on media and time - Cornell ...

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A size is not a coating, it is a penetrating liquid employed to fill pores and to make surfaces suitable to receive coatings. It is used to seal and solidify the support, and acts as a guard against deterioration and mold. In the case of flexible supports, size shrinks the fabric to a taut, smooth membrane. Hence, on drying it should become somewhat tighter and free from folds and wrinkles. 2.1.3 Ground The next intermediate layer between a support and subsequent paint films is a ground. Most supports will be unevenly absorbent, even if they have been correctly sized. A ground is to ensure that a particular kind of paint will perform with reasonable predictability. Mark Gottsegen writes that grounds should meet a few basic requirements [Got87]. A ground should be white–some paint films grow more transparent with age and the respective colors will lose their relative relationships if the ground is not white. Also, since the ground is a structural element for the paint to grip, it should have a tooth and should be somewhat absorbent. This ensures proper paint deposition and adhesion as a brush moves across the surface. For flexible supports, the ground should not be too much affected by the continuous movement of the support. Brittle grounds and paint films should use more rigid supports. The ground provides a better adherence of the subsequent paint layers. A ground is essentially a paint, made of materials compatible with the support material and the paint to be used. Gesso–a mixture of animal skin glue, chalk (calcium carbonate), and sometimes white pigment (powdered colorant)–has been used for centuries as a ground for wooden panels and canvas. Traditional gesso yields a highly reflective, opaque surface. Light that passes through the layers of the paint- 15
ing will hit the ground and reflect back toward the viewer creating a luminous surface. Figure 2.5: Two magnified views of cotton canvas, partially primed on the top of each image with three coats of acrylic gesso. Notice how the primed surface still maintains the original surface characteristics. There is a common product available today at most art suppliers that is labeled “gesso”, but it is different from traditional gesso. Usually, it is actually a form of white pigment suspended in an acrylic polymer emulsion. While this “gesso” is a viable alternative (as it is freely available, ready to use, and reasonably priced), acrylic itself is a medium that has not been used in art for enough years for artists or conservationists to be certain of its stability or longevity. Hence, it is uncertain how it will affect overlying media as the work ages. 2.2 Composition of Paint The most basic paint is comprised of powdered colors suspended in a liquid to help ease spreading. The nature of this liquid is crucial to the tactile and optical behavior of the paint. The component we perceive as hue in paint is known as pigment, or a fine colored powder of organic or inorganic material. The liquid that the pigment is dispersed in is the binder, which adheres the particles of pigment to 16
Page 1 and 2: PIGMENTED COLORANTS: DEPENDENCE ON
Page 3 and 4: ABSTRACT We present a physically ba
Page 5 and 6: Acknowledgements This work would no
Page 7 and 8: Table of Contents 1 Introduction 1
Page 9 and 10: List of Tables 2.1 Average pigment
Page 11 and 12: 3.15 Photoreceptor absorption .....
Page 13 and 14: B.15 Variation of spectral reflecta
Page 15 and 16: corrode the surfaces of materials.
Page 17 and 18: Figure 1.1: Detail of the Azor-Sado
Page 19 and 20: However, since mural artwork is typ
Page 21 and 22: at a very high quality (albeit limi
Page 23 and 24: heterogeneous sum of very different
Page 25 and 26: which linseed oil derives (the most
Page 27: oration of a rigidly painted layer
Page 31 and 32: tion of paint tubes in 1841 and the
Page 33 and 34: Figure 2.8: Natural pigments of ant
Page 35 and 36: ecome more common recently. The Ame
Page 37 and 38: A V = O(r2 ) O(r3 ) = 1 O(r) 24 (2.
Page 39 and 40: Table 2.2: Pigment specific gravity
Page 41 and 42: provide the underlying color to a p
Page 43 and 44: though the speed of light in air is
Page 45 and 46: In general, when light travels from
Page 47 and 48: materials while lit from behind. Li
Page 49 and 50: Table 2.4: Index of refraction η f
Page 51 and 52: to completely congeal. Hence, these
Page 53 and 54: ond together to form proteins. Exam
Page 55 and 56: to its original state by any means.
Page 57 and 58: While it has been used since the 19
Page 59 and 60: organic binder found in more conven
Page 61 and 62: 3.1.1 Visible Light Spectrum Light
Page 63 and 64: Figure 3.2: Hue, brightness and sat
Page 65 and 66: measures how much light is reflecte
Page 67 and 68: Figure 3.6: Additive color mixing o
Page 69 and 70: Figure 3.9: The physical amount of
Page 71 and 72: The vascular tunic lies on the wall
Page 73 and 74: Figure 3.11: Cross section of the r
Page 75 and 76: Not all areas have the same sensiti
Page 77 and 78: identify and distinguish between va
Page 79 and 80:
that range between zero and full in
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spectrum. This insures that the res
Page 83 and 84:
Figure 3.19: Graphical representati
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X x = (X + Y + Z) Y y = (X + Y + Z)
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color into the appropriate RGB colo
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components in the image (the smalle
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haviors of subtractive mixing and i
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of perceptually equal sizes. Unfort
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enabling one to transform between t
Page 97 and 98:
andwidth as converted signals are s
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Figure 3.28: Retinal ganglion recep
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example shown in Figure 3.28. Under
Page 103 and 104:
Figure 3.31: The work of Josef Albe
Page 105 and 106:
sensations for each trial and picke
Page 107 and 108:
Chapter 4 Previous Work There is no
Page 109 and 110:
different location. Subsurface scat
Page 111 and 112:
describes the scattering and absorp
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only accounts for a small percentag
Page 115 and 116:
σ ′ t = σa + σ ′ s and α
Page 117 and 118:
104 Figure 4.4: A model of an alaba
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effects or are too computationally
Page 121 and 122:
108 Figure 4.6: Results using Kubel
Page 123 and 124:
specifying pigments works adequatel
Page 125 and 126:
color representation, it is not fea
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time. A metallic surface patina is
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the system consisted of wetness and
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or darkening enables the museum per
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in front of a displayed work. Felle
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light exposure. This effect is espe
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over time. Perceptually, these hues
Page 139 and 140:
The rate of change of the concentra
Page 141 and 142:
over white grounds) suffer the grea
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protects the deeper remaining color
Page 145 and 146:
light source. This method is used w
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chemical smog and have been identif
Page 149 and 150:
Chapter 5 Preparation & Measurement
Page 151 and 152:
tending transparent pigments used i
Page 153 and 154:
140 Figure 5.1: Spectral reflectanc
Page 155 and 156:
the requirements of the work at han
Page 157 and 158:
144 Figure 5.2: Left: Magnified vie
Page 159 and 160:
Table 5.2: Relevant data regarding
Page 161 and 162:
historically one of the best grades
Page 163 and 164:
created far too strong of a binder,
Page 165 and 166:
too brittle and cracking. While wor
Page 167 and 168:
154 Figure 5.4: Reflectance values
Page 169 and 170:
5.1.5 Painting After the layers of
Page 171 and 172:
The gray card reflected 18% of the
Page 173 and 174:
160 Figure 5.8: The optical setup f
Page 175 and 176:
Note that harmonics reflect at the
Page 177 and 178:
Note that the calibration factors f
Page 179 and 180:
Chapter 6 Experimental Results 6.1
Page 181 and 182:
168 Figure 6.1: Lapis Lazuli in dif
Page 183 and 184:
(such as CIE standards C, D50, orD6
Page 185 and 186:
172 Table 6.2: Perceptual differenc
Page 187 and 188:
174 Figure 6.3: Munsell plots of La
Page 189 and 190:
and j has a saturation of red rsat,
Page 191 and 192:
178 Figure 6.4: Variation of spectr
Page 193 and 194:
visible spectrum are increasing at
Page 195 and 196:
182 Figure 6.5: Munsell plots of La
Page 197 and 198:
trying to match color ca from the p
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as it ages. This is in direct contr
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teractive viewer. In our applicatio
Page 203 and 204:
190 Figure 7.1: Our simulated canva
Page 205 and 206:
where n is the normal at the curren
Page 207 and 208:
In summary, our implementation prov
Page 209 and 210:
Chapter 8 Conclusion We have studie
Page 211 and 212:
inks are beginning to find their wa
Page 213 and 214:
Appendix A Derivation of K-M theory
Page 215 and 216:
∆i − =(K + S) idx 202 ∆j −
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Equation A.8 is now: Rearranging yi
Page 219 and 220:
and if the paint is infinitely thic
Page 221 and 222:
One concatenates the layers into a
Page 223 and 224:
210 Figure B.1: Cold Glauconite in
Page 225 and 226:
Table B.1: Color conversions from t
Page 227 and 228:
214 Figure B.4: Munsell plots of Co
Page 229 and 230:
216 Figure B.5: Burnt Sienna in dif
Page 231 and 232:
Page 233 and 234:
220 Figure B.8: Munsell plots of La
Page 235 and 236:
222 Figure B.9: Red Ochre Tint in d
Page 237 and 238:
Page 239 and 240:
226 Figure B.12: Munsell plots of C
Page 241 and 242:
228 Figure B.13: Variation of spect
Page 243 and 244:
230 Figure B.15: Variation of spect
Page 245 and 246:
Table B.13: Color conversions of Bu
Page 247 and 248:
234 Figure B.18: Munsell plots of C
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236 Figure B.20: Munsell plots of R
Page 251 and 252:
References [Alb71] Josef Albers. In
Page 253 and 254:
240 [GLL + 04] Michael Goesele, Hen
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242 [KM31] Paul Kubelka and Franz M
Page 257 and 258:
[Rat72] Floyd Ratliff. Contour and
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