Dry Pigment Research Articles

Effect of opacifiers and UV absorbers on pigmented maxillofacial silicone elastomer, part 1: Color stability after artificial aging

Much dissatisfaction with the color instability and reduced lifetime of extraoral maxillofacial prostheses due to degradation has been reported. The purpose of this study was to compare the effect of a UV mineral-based light protecting agent (LP) on the color stability of pigmented maxillofacial silicone elastomer MDX-4210/Type A after artificial aging to 2 widely used opacifiers. Forty-five groups were established (n=225 total). Three different types of opacifiers (LP, titanium white dry pigment [TW], or silicone intrinsic white [SW]) were added to silicone MDX-4210/type A at 3 concentrations (5%, 10%, or 15%) and subsequently combined with each of 5 colors (no pigments [control], red, blue, yellow, or mixed pigments). Artists' oil pigment was used with LP and TW, while intrinsic silicone pigment was used to color SW. Before and after an energy exposure of 450 kJ/m(2), CIE L*a*b* values were measured with a spectrophotometer. The CIELAB 50:50% perceptibility (ΔE*=1.1) and acceptability threshold (ΔE*=3.0) were used to interpret color changes (ΔE*). Color differences after aging were subjected to 3-way ANOVA. Means were compared by the Fisher PLSD intervals at α=.05. The ΔE* values of all groups were below the acceptability threshold of ΔE*=3.0, except for the control group of SW at 10%, which showed the greatest color change (ΔE*=3.1). When mixed pigment groups were considered, at 5% concentration, LP showed the smallest color change, followed by SW and TW (P<.05); at 10%, no significant differences among the 3 opacifiers were noted (P>.05); at 15%, LP showed the smallest color change, followed by TW and SW (P<.05). All 3 opacifiers at all concentrations protected pigmented silicone MDX4-4210/Type A from color degradation. The LP group showed the smallest color changes.

Cytotoxicity of the coloring pigments used with maxillofacial silicone

Maxillofacial prosthesis silicone base material is colored using various pigments according to the patient\'s skin color. Primary color pigments are used in the coloring maxillofacial silicones, silicone base, water base, oil base and as dry pigments commercially available. In the study the aim was compared of cytotoxicity between colored non colored silicones. A 2000-1 platinum silicone material formed five separate groups. Control group without any colorant pigment and other groups using four different colored pigments. The cytotoxicity of all groups of L-929 fibroblast cell culture was investigated in vivo by measurement of MTT. Results were evaluated using ANOVA and t test. According to the results there were statistically differences between colored and no colored silicones (p = 0.00000002). The measurement of MTT cell viability are listed from less to more; dry pigments, oil based, water based and silicone based. Measurements of cell viability are not toxic level so coloring pigments is considered biocompatible.

Positive effects of nitric oxide on Solanum lycopersicum

The present work examines benzoic acid (BA) induced stress in Solanum lycopersicum and explores the possible mechanism through which sodium nitroprusside (SNP) protects plants. Tomato seeds were soaked for 3 h in 250 µM SNP and 0.5, 1.0, and 1.5 mM BA with and without SNP. Seeds soaked in distilled water were treated as control. Seed germination (SG) and radicle length (RL) were recorded in Petri plate culture. SG and RL inhibition was concentration dependent in BA. SNP enhanced SG and RL. Twenty-one-days old seedlings were grown in hydroponic culture in Hoagland solution and BA at 0.5, 1.0, and 1.5 mM with and without SNP. The morphological and biochemical parameters of seedlings were assayed. Average growth rate of root and shoot, dry weight, sugar, pigment and protein content, and activity of nitrate reductase decreased in seedlings treated with BA while increased in SNP with and without BA. Lipid peroxidation increased in seedlings treated with BA but decreased in BA+SNP. SNP protected the seedlings against BA induced oxidative stress by scavenging reactive oxygen species. SNP demonstrated a positive role against BA toxicity which was evident from increased activities of antioxidant enzymes.

Contribution to the identification of α‐, β‐ and ε‐copper phthalocyanine blue pigments in modern artists' paints by X‐ray powder diffraction, attenuated total reflectance micro‐fourier transform infrared spectroscopy and micro‐Raman spectroscopy

Since the end of the 20th century, the α‐, β‐ and ε‐copper phthalocyanine (CuPc) blue pigments are widely used in modern artists' paints. The identification of the CuPc crystalline structure can provide useful technical and chronological information for the study of works of art. Although when a CuPc blue pigment is identified, its crystalline structure often remains unspecified despite the interest for conservation science. In this study, X‐ray powder diffraction, attenuated total reflectance micro‐Fourier transform infrared spectroscopy and micro‐Raman spectroscopy analyses have been carried out on 15 dry pigment samples of CuPc and acrylic, vinylic, alkyd, arabic gum and oil‐based artists' paints. By using the polymorphic markers underlined for dry pigments, the CuPc crystalline structure has been successfully identified for most of the analysed artists' paints. However, according to the analytical technique used and the investigated paint sample, the obtained results largely differ. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Comparative Evaluation of the Effects of Bone Powder and Calcium Phosphate on Plant Growth and Development

The present study aimed to elucidate the effectiveness of inorganic element composition (except for calcium and phosphorus) of bone powder (BP) on some morphological (root and shoot length and dry weight) and biochemical (protein, sugar, chlorophyll, and inorganic element contents) parameters in bean seedlings. For this, BP was compared with calcium phosphate (CP), which is used as calcium and phosphorus source. Bone powder solutions (BPS) (0.5, 1, 1.5, and 2%) and CP solution (0.1 M) were applied to growing media of 12-day bean seedlings. Seedlings were harvested on 20th day. Both BPS and CP treatments significantly stimulated plant growth and increased dry weight, pigment, protein, and sugar contents compared to control seedlings; however, BPS treatments were found to be more effective than CP treatment. The best stimulatory effect on plant growth was determined at 1.5% concentration of BPS. Besides, BP treatment significantly increased contents of K, S, Fe, Zn, Mg, Mn, and Cu compared to control and CP-treated seedlings. This result clearly elucidated that the other elements existing in structure of BP also participated in plant structure, and they played important roles on growth and development in bean seedlings. It is possible to say that BP may be used as an important source of the other inorganic elements as well as Ca and P in agriculture studies for improving of plant growth and productivity. This is the first report revealing the effect of BP on inorganic element content of plants.

Large-scale assessment of light-induced color change in air and anoxic environments

A wide-ranging sample set consisting of dry pigments, dyed textiles, organic and aniline-based dyes, gouaches and watercolors, fluorescent inks, and natural history specimens was exposed to light in air (20.9% oxygen) and near-anoxic environments. After a light dosage of approximately 17.5 Mlux-hours under controlled temperature and humidity conditions, 113 of 125 samples (90% of the sample set) were shown to exhibit less color change in a low-oxygen environment compared with its behavior in air. Thirty-nine percent of this subset displayed color change in anoxia that was between two and four times lower than that observed in air, whereas 47% showed color change in anoxia reduced by a factor of four or more. In contrast, six samples exhibited greater color change in anoxia than in air – these samples included Prussian blue watercolor (three samples), Antwerp blue watercolor, Verdigris dry pigment, and Fluorescent Yellow Winsor & Newton Gouache. Although the results from this small sample subset may cause concern when considering the use of anoxia in the conservation of cultural heritage, particularly for colorant systems whose behavior in anoxia has not yet been identified, this study demonstrates the overwhelming benefits of anoxic light exposure for the vast majority of samples investigated here.

Potential activity of basil plants as a source of antioxidants and anticancer agents as affected by organic and bio-organic fertilization.

Sweet basil (Ocimum basilicum) is a popular culinary herbal crop grown for fresh or dry leaf, essential oil and seed markets. Recently, basil was shown to rank highest among species and herbal crops for phenolic compounds, essential oils which are associated with decreasing risks of cancer and aging diseases. The current study aimed to evaluate the potential activity of phenolic, flavonoids and essential oil of basil as antioxidant and anticancer activities by application organic and bio-organic fertilization. A pot experiment was conducted. Basil seeds were grown, with three levels of organic fertilizers (compost) in presence or absence of biofertilizer. Growth parameters, pigments content, total phenolics, total flavonoids and antioxidant activity of methanolic plant extract were examined. Application of 50% compost and 50% sand in the presence of biofertilizer resulted in enhancement fresh and dry weights, total phenolics, total flavonoids and pigment content as compared with compost alone. The constituents of essential oils extracted by hydrodistilation of basil leaves were identified by GLC. Eleven components of essential oils were identified. The highest value of antioxidant and anticancer activities were obtained in basil plants grown in 50% and 75% compost treatments in the presence of biofertilizer. These results emphasized the important of bioorganic fertilizers for enhancement the antioxidant activity of phenolics, flavonoids, and essential oils of basil plant extract.

The effect of accelerated ageing on performance properties of addition type silicone biomaterials

The UV-protection provided to addition type silicone elastomers by various colorants, such as conventional dry earth pigments, as well as the so called "functional or reactive" pigments, was investigated. Moreover, the effect of a UV light absorber and a silica filler was also explored. Under the experimental parameters of this work, the exposure of silicone to UV radiation resulted in some changes of the IR absorbance, thermal decomposition after 400 degrees C, T(g) and tensile properties, whereas the storage modulus of samples was not affected. The obtained spectroscopic data, as well as the results of TGA and storage modulus, were interpreted by assuming that chain scission takes place during aging, whereas the improvement of tensile strength allows the hypothesis of a post-curing process, initiated by UV radiation. Therefore, the increase of T(g) could partly be due to the above reason and, furthermore, to the contribution of a rearrangement of chain fragments within the free volume of the elastomeric material. Regarding the evaluation of various coloring agents used in this work, the obtained results show that dry pigments are more sensitive to accelerated ageing conditions in comparison with functional liquid pigments. Moreover, the hydrophobic character of silicone matrix is enhanced, with the addition of this type pigments because of the vinyl functional silanes groups present in their chemical structure. Finally, it should be noted that the incorporation of silica nanofiller did not seem to prevent the silicone elastomer from degradation upon UV irradiation, but showed a significant reinforcing effect.

The application of x-ray powder diffraction for the analysis of synthetic organic pigments. Part 1: dry pigments

The application of x-ray powder diffraction for the analysis of synthetic organic pigments. Part 1: dry pigments

EFFECT OF SUCROSE LEVEL ON THE PHOTOSYNTHETIC ABILITY OF IN VITRO CULTIVATED APPLE ROOTSTOCK MM 106

The aim of the present research was to observe the effect of sucrose level in the nutrient media on the photosynthetic ability of in vitro cultivated apple rootstock MM 106. The plantlets in an elongation stage (hormone-free medium) were grown at different sucrose concentrations (0, 1, 2 and 4% w/v) in the medium and in vessels with two types of closures - tight closure (T - gas exchange rate of 0.013 volumes/hour) and gas-permeable closure (G - gas exchange rate of 3 volumes/hour). The net photosynthetic rate (light and CO 2 curves), chlorophyll fluorescence and chlorophyll content were observed. There was a positive correlation between sucrose concentration and accumulation of dry matter and light-harvesting pigments. However, the increased sucrose concentration leads to a decrease in the net photosynthetic rate (Pn) of the plantlets. Plantlets cultivated with gas-permeable closure without sucrose showed the highest value of the Genty-parameter and ETR. The highest increase of the leaf area was achieved in plantlets cultivated on medium with 1 % sucrose and gas-permeable closure. Results from this study showed that in vitro cultivated apple plantlets could develop a positive carbon balance at suitable parameters of environmental factors (mainly light intensity, CO 2 concentration and sucrose in the nutrient medium).

Influence of pigments and opacifiers on color stability of silicone maxillofacial elastomer

Objectives To determine the effects of opacifiers and silicone pigments on the color stability of silicone A-2000 maxillofacial prosthetic elastomers subjected to artificial aging. Methods Seventy-five groups ( n = 5) were made by various combinations (5%, 10%, and 15%) of four dry earth opacifiers (Georgia kaolin, Gk; calcined kaolin, Ck; Artskin white, Aw; titanium white dry pigment, Td); and 1 silicone pigment white (Sw) with one of 5 silicone pigments (no pigment (control), red (Pr), yellow (Py), burnt sienna (Po), and a mixture of Pr + Py + Po). A reflection spectrophotometer was used for color measurements. Color differences (Δ E*) between baseline and after an energy exposure of 450 kJ/m 2 in an artificial aging chamber were calculated. A Δ E* = 3.0 was used as 50:50% acceptability threshold in result interpretation, while Δ E* = 1.1 was used as 50:50% perceptibility threshold. Means were compared by Fisher's PLSD intervals at the 0.05 level of significance. Color differences after aging were subjected to three-way analysis of variance. Results Yellow ochre mixed with all opacifiers at all intervals had increased Δ E* values significantly from 0.7–2.1 up to 3.8–10.3. When mixed groups were considered, at 5%, Gk exhibited the smallest color changes, followed by Td < Aw = Sw < Ck, respectively. At 10%, Aw < Td < Gk < Sw = Ck. At 15%, Td < Aw < Gk = Sw < Ck (< indicates p < 0.0001 and = indicates p > 0.05). The smallest color differences, observed for opacifier groups, were recorded for Gk at 5%, and Td and Aw at 10% and 15%. Overall, 15% Td exhibited the smallest, whereas 5% Ck exhibited the most pronounced color change after artificial aging. All Δ E* values were below the 50:50% acceptability threshold, indicating acceptable color stability. Color differences for 10% and 15% of Aw and Td were below 50:50% perceptibility thresholds, indicating excellent color stability. Conclusion Silicone pigments mixed with 10% and 15% Artskin white and titanium white dry pigment opacifiers protected silicone A-2000 from color degradation over time. Yellow silicone pigment significantly affected color stability of all opacifiers especially silicone pigment white and calcined kaolin.

Dynamic sketches: 6000+ year old dry‐pigment drawings from Arnhem land

ABSTRACT A unique example of ‘Dynamic Figures’ style motifs drawn with dry pigment was recently located in south‐western Arnhem Land. One of these figures has been partially over‐painted with wet pigment, suggesting that the drawings were produced as sketches for the painting of Dynamic Figures. The implications for rock art research are discussed.

Interactions of pigments and opacifiers on color stability of MDX4-4210/type A maxillofacial elastomers subjected to artificial aging

The color instability and degradation of maxillofacial elastomers limit the function and cosmetic quality of facial prostheses. The purpose of this study was to measure the interactions of oil pigments plus dry earth opacifiers at 5%, 10%, and 15% by volume in stabilizing the color of MDX4-4210/type A silicone elastomers before and after artificial aging. In the first part of the study, each of 5 opacifiers (Georgia kaolin powder neutral, kaolin powder calcined, Artskin white, dry pigment titanium (Ti) white, or Ti white artists' oil color) at 10% concentrations were combined with each of 5 oil pigment types (no pigment, cadmium-barium red deep, yellow ochre, burnt sienna, or a mixture of the 3 pigments), for a total of 25 experimental groups of elastomers. In the second part of the study, 50 experimental groups of elastomers were made by combining 1 of 5 opacifiers at 5% and 15% concentrations with 1 of 5 oil pigments as in Part 1. Five specimens of each elastomer were tested, for a total of 375 specimens. In each part of the study, all specimens were aged in an artificial aging chamber. CIE L*a*b* values were measured by a spectrophotometer. The color differences (DeltaE*) were subjected to repeated-measures analysis of variance. Mean values were compared by Tukey-Kramer intervals (alpha = .05). In Part 1, when the opacifiers were tested at 10% concentration, Ti white oil color had the most color change, and dry pigment Ti white had the least; all other opacifiers were not significantly different from each other. In Part 2, at 5%, Ti white oil color had the most color change; all other opacifiers were not significantly different from the others. At 15%, Ti white oil color again had the most color change, followed by Artskin white, kaolin powder calcined, and Georgia kaolin; Ti white dry earth pigment had the least color change. Overall, 5% Artskin white had less color change than the 15%, whereas 15% dry pigment Ti white had less color change than the 5% (P < .001). The 5% and 15% of other opacifiers were not significantly different. At all 3 concentrations, oil pigments mixed with opacifiers helped protect the MDX4-4210/type A silicone elastomer from color degradation over time. Dry pigment Ti white remained the most color stable over time, followed by the pigments mixed with kaolin powder calcined, Georgia kaolin, Artskin white, and Ti white artists' oil color.

The Characterization of Cobalt Violet Pigments

The study of several commercial paints and dry pigments, as well as paint samples removed from works of art, allowed the identification of magnesium cobalt arsenate, a pigment that has not previously been reported in the literature. This article focuses on the composition, characterization and occurrences of this pigment as well as other violet cobalt compounds used as artists' pigments, namely cobalt phosphate, cobalt phosphate octahydrate, ammonium cobalt phosphate hydrate and lithium cobalt phosphate. Cobalt arsenate, a pigment frequently mentioned in the literature on artists' materials, has not yet been unambiguously identified. The introduction of these compounds as pigments is briefly discussed.

Effect of opacifiers on color stability of pigmented maxillofacial silicone A‐2186 subjected to artificial aging

This study was designed to determine the effect of opacifiers used at different ratios on the color stability of pigmented A-2186 silicone maxillofacial elastomers and to evaluate the color spectrophotometrically before and after artificial aging. Sixty experimental groups of elastomers were made using various concentrations (5%, 10%, and 15%) of 4 opacifiers (Georgia kaolin powder neutral, kaolin powder calcined, Artskin white, and dry pigment titanium white) with 1 of 5 dry earth cosmetic pigment groups (no pigment [control], red, yellow ochre, burnt sienna, and a mixture of all pigments). Five specimens of each elastomer were tested, for a total of 300 specimens. All specimens were placed in an aging chamber and artificially aged by exposure to light, water spray, fluctuating temperatures, and humidity. CIE L*a*b* values were measured by spectrophotometer. The color differences (Delta E*) at various exposure energies (150, 300, and 450 kJ/m(2)) were subjected to 4-way analysis of variance with repeated measures (super ANOVA). Mean values were compared with Tukey-Kramer intervals calculated at the 0.05 significance level. The trained human eye can detect color changes (Delta E*) greater than 1.0. Adding all pigments to any of the kaolin groups did not protect silicone A-2186 from color degradation over time. Mixing red pigment in all groups at all times drastically increased DeltaE* values ranging from 0.1 to 1.3 up to 16.6 to 49.6. Yellow ochre had an effect only with 10% and 15% concentrations of kaolin powder calcined, increasing the value of Delta E* to greater than 1.0. Burnt sienna had an effect only with a 15% concentration of kaolin powder calcined, increasing the value of Delta E* at 300 and 450 kJ/m(2) to greater than 11.0. At the 5% concentration, kaolin powder calcined had the smallest color changes, followed by, in order, dry pigment titanium white, Artskin white, and Georgia kaolin. At the 10% concentration, Artskin white had the smallest color changes, followed by, in order, dry pigment titanium white, kaolin powder calcined, and Georgia kaolin. At the 15% concentration, Artskin white again had the smallest color changes, followed by, in order, dry pigment titanium white, Georgia kaolin, and the kaolin powder calcined. The smallest color changes in each kaolin group were at the 10% concentration for Artskin white, dry pigment titanium white, and kaolin powder calcined and at the 5% concentration for Georgia kaolin. Mixing dry earth cosmetic pigments with opacifiers did not protect silicone A-2186 from color degradation over time, especially in the case of red pigment. The group in which pigments were mixed with 10% Artskin white had the smallest color changes over time, followed by, in order, the groups in which pigments were mixed with 10% dry pigment titanium white, 10% kaolin powder calcined, and 5% Georgia kaolin. Red pigment had a significant effect on all opacifiers, especially Georgia kaolin and kaolin powder calcined. Yellow ochre and burnt sienna had an effect only on 15% kaolin powder calcined. Among all the pigment groups tested, yellow ochre remained the most color stable over time.

Relation of the fractal structure of organic pigments to their performance

Different pigments embedded in polymer matrices were examined by small angle scattering of x- rays over 3 wave number decades. The scattering intensities show differences both in the mass fractal dimension (varying between 1.4 and 2.67) and the size of the particles. The differences are pronounced between dry pigment powders and the same powders in a polymer matrix as well as between the pigments themselves. Further, a correlation of pigment geometrical configuration and pigment performance, as perceived by the human eye, shows how pigments with a maximum color brightness per pigment mass can be created.

Some alternative strategies in matching and toning paper and parchment for repair of books and manuscripts

Summary This article describes some of the methods used to tone repair materials, in particular use of the airbrush with watercolour pigment whilst repairing leaves of a copy of the Discorsi of Pierandrea Mattioli. The principles of repair are discussed, and a selection of available materials and methods, including Japanese tissues, western hand-made papers, blank original leaves and leaf-casting techniques are outlined. Traditional aqueous methods of dyeing parchment and methods of toning modern skins with solvent dyes are described. The nature of the dyeing process and the use of direct and fibre reactive dyes for paper are discussed, together with the use of the fixative Sandofix WEM. Other treatment options considered are the use of dry pigments, ‘palimpsest’ repairs for vellum manuscripts, and a method of treating modern vellum with polyethylene glycol to make it more compatible with original material.

EFFECTS OF ZIRCONIUM ON THE GROWTH AND PHOTOSYNTHETIC PIGMENT COMPOSITION OF CHLORELLA PYRENOIDOSA GREEN ALGAE

The effects of zirconium (Zr) were investigated on the growth rate, dry matter accumulation, and elemental and photosynthetic pigment composition of Chlorella pyrenoidosa green algae. Algae were treated with 0.1–50 μM (≈ 0.009–4.561 mg dm−3) of Zr; inorganic compounds (Zr oxychloride, Zr nitrate) and organic chelates (Zr ascorbate or Zr citrate) were applied. All Zr compounds displayed only a slight insignificant inhibitory effect on the growth rate of algae. Treatment of algae with 1 μM Zr (as Zr ascorbate, a water soluble pH stable chelate) slightly stimulated and 5–50 μM Zr slightly inhibited the dry matter accumulation of Chlorella. Zirconium concentration in the nutrient solution decreased rapidly during the algae propagation, and Chlorella cells accumulated significant amounts of Zr. In the case of 1 μM Zr (Zr ascorbate) treatment, 60.6 μg g−1 Zr was found in the washed cells; after 50 μM Zr application this value was 441 μg g−1 Zr. Zirconium treatment reduced the P, Mg, Cu, and Ti concentrations in algae cells, and the concentration of Fe, Mn, and partly Zn was enhanced. Chlorophyll a, chlorophyll b, xanthophyll, and carotenoid concentrations were equally reduced by 13–33% in Zr-treated cultures. Zirconium treatment changed the chlorophyll a:chlorophyll b ratio and caused appearance of several new chlorophyll derivatives in Chlorella.

Remedying the iron-deficient maize plants grown at lower than the optimal temperature and irradiance by new synthetic macromolecular iron-chelating agents

Summary The efficacy of Fe 3+ complexes of polyethers having chelating terminal 8-quinolinol (8QOH) residues for remedying the iron-deficient maize plants at temperatures of 20/16°C and photosynthetic photon flux density (PPFD) 500-600 μmol m -2 s -1 was evaluated by their effect on the fresh and dry weight, pigment content (total chlorophyll and carotenoids), chlorophyll fluorescence, and photosynthetic activity of maize plants. In order to estimate the effect of the oligomer nature of the polyethers with 8QOH group attached to the oxyethylene chain at different positions of aromatic ring, tests on chlorotic plants were also performed with Fe 3+ complexes of low-molecular-weight ligand 8QOH, and mixtures of commercial polyethers with isopropylamino end-groups (Jeffamines ED) and 8QOH (Jeff/8QOH). The efficacy of Fe 3+ chelates of synthetic chelator ethylenediaminetetraacetic acid and FeCl 3 · 6H 2 O for remedying the chlorotic maize plants under the same conditions was also tested. At temperatures of 20/16 °C and PPFD 500-600 1J.mol m-2 s-1 , the Fe3+ chelates of polymers with 8QOH groups attached at 5-position were the most effective for remedying the iron-deficient maize plants compared to the other tested Fe 3+ complexes. It was found that the plant remedy process was sensitive to lowering of the temperature and PPFD. The remedy of chlorotic maize plants supplied with investigated Fe 3+ complexes at 20/16 °C (day/night) and PPFD 500-600 μmol m -2 s -1 retarded 4-fold compared to that observed at 30/25 °C and PPFD 1100-1300 μmol m -2 s -1 . We concluded that the longer period for remedying the iron-deficient maize plants at lower than the optimal temperature and PPFD is probably due to the fact that, under these conditions, the amount of DMA released from roots is several times lower, and the efficiency of the high-affinity system for uptake of Fe 3+ -PS is decreased as compared to that at optimal temperature and PPFD.

Investigation of the Physical Properties of Some Pigmented Inks and their Mechanism of Dispersion

In this study, we investigate the physical properties of some pigment based inks that we have formulated in our laboratory. We have used commercially available specially treated surface modified as well as unmodified dry pigments in these formulations. In both cases we have achieved the stable dispersion of pigment particles by appropriate selection of ingredients of compatible physical properties for ink formulation Furthermore, the influence of ink composition and other physical conditions like temperature, solvent mixture, dielectric constants and surface tension were investigated to study their effects on ink stability as well as print quality. We have shown that by controlling the composition, we can easily achieve the desired physical parameters required for proper ink jet printing operation. Based on these results, and considering the interrelationships of different physical parameters, a plausible mechanism of dispersion will be discussed for the stability and shelf life of pigment based inks.