Abstract
Persimmon dye is a natural dye potentially used to promote sustainable textile industry. In this article, cotton and wool fabrics were dyed with persimmon dye. The performance of the dye was characterized using color strength and appearance analysis (ColorQuest), American Association of Textile Chemists and Colorists colorfastness tests, and Fourier transform infrared spectroscopy (FTIR). The results showed color strength of dyed cotton and wool fabrics was enhanced with increasing dye concentration and dyeing times. The comparison between cotton and wool suggested persimmon dye exhibits better dyeing performance (higher color strength and higher colorfastness ratings) on wool fabrics than on cotton fabrics. The FTIR analysis indicated no significant chemical reactions or changes in persimmon dye occurred to dyed fabrics, suggesting negligible impact on chemical and physical properties of the dyed fabrics. The reported results are valuable in exploring the opportunity of using persimmon dye as a useful natural dye for a sustainable textile dyeing industry, especially in the case of dyeing natural fibers.
Natural dyes were the primary textile dyeing materials before the advent of synthetic dyes and pigments. Natural dyes are usually obtained by extracting colorants from roots, stems, berries, leaves, and flowers of various plants (Arora, Rastogi, Gupta, & Gulrajani, 2012). It is well known that natural dyes are a safe, eco-friendly alternative to synthetic dyes (Mirjalili, Nazarpoor, & Karimi, 2011). Although there are drawbacks of using natural dyes, such as limited availability and less colorfastness, natural dyes are becoming increasingly important as benefits other than coloration are being discovered, resulting in an expansion in the scope of applications. For example, turmeric was found to possess antimicrobial properties (Ghoreishian, Maleknia, Mirzapour, & Norouzi, 2013) and was able to achieve good color strength on polyamide fibers (Mirjalili, & Karimi 2013). Also, some natural dyes were reported to alter mechanical properties such as tensile strength (Kourkoumelis, El-Gaoudy, Varella, & Kovala-Demertzi, 2012). Researchers were also able to use some natural dyes as ink-jet ink to digitally print cotton (Savvidis, Karanikas, Nikolaidis, Eleftheriadis, & Tsatsaroni, 2013), further increasing natural dyes’ ability to compete with synthetic dyes in cutting-edge dyeing applications. Natural dyes are also restricted not just to fabric applications; dyes extracted from grasses were able to harvest light in solar cells (Shanmugam, Manoharan, Sharafali, Anandan, & Murugan, 2014). These new developments suggest natural dye use will remain important in the future.
Persimmon dye is a naturally occurring dyestuff made from persimmon juice. The colorant in persimmon juice is tannin, which is dark brown to almost black (Park, Kim, Suh, Kim, & Hwang, 2005). Persimmon-dyed fabrics and clothing are well known in Asian cultures and art (Ko, 2010; Lee & Yi, 2013). Additional superior properties of the persimmon-dyed fabric have been reported, including high-tensile strength, ultraviolet resistance, waterproof abilities, and fungal resistance (Park, 1995). Persimmon juice was also traditionally used to reinforce cloth and other materials like fishnets, suggesting that the dye could increase substrate strength and would hold up well during consumer use (Arakawa, Takasaki, Tajima, Fukamachi, & Igarashi, 2014). These characteristics could make its performance on fabrics superior to other natural dyes for some applications. Persimmon dye can also achieve acceptable color strength under a wide range of conditions. Yi and Cho (2008) dyed fabric by dipping it in the persimmon dye at room temperature, yielding a faster process compared to many natural dyes that require a dyeing temperature around 100°C. Therefore, persimmon dye could become an important alternative dye for a sustainable textile dyeing industry.
Although persimmon-dyed fabrics have been studied, most existing studies are limited to textile appearance and aesthetics. Current knowledge of persimmon dye and its use in textile dyeing is still limited, particularly in terms of the relationship between dyeing procedures (and conditions) and dyeing performance. The dyeing procedures for persimmon dye in previous studies varied significantly. To our best knowledge, no systematic study on persimmon dye performance has been conducted on dyeing conditions, such as temperature, dyestuff concentration, and dyeing time. Also, most previous researchers focused only on cotton fabrics. In this article, we investigated the relationship between persimmon dyeing performance with various dyeing conditions (temperature, dyeing time, and dyestuff concentration) on both cotton and wool fabrics. In our experiments, colorfastness properties were used to determine persimmon dye performance on cotton and wool fabrics. Chemical compositions of persimmon dye and dyed fabric samples were evaluated using Fourier transform infrared spectroscopy (FTIR) to determine whether any chemical changes occurred in dyed fabrics after dyeing. The results of this study are useful when persimmon dye is used to create natural fabrics and for further studies on determining the viability of persimmon dye for use in textile products.
Material and Method
Materials
The fabrics used in this study were plain-woven fabrics obtained from Testfabrics Inc. (West Pittston, PA). The cotton (style 400M) was bleached and mercerized and had the following characteristics: 107 g/m2 weight, 150 count, and 0.356 mm thickness. The wool (style 527) was carbonized and had the following characteristics: 255 g/m2 weight, 57 count, and 0.965 mm thickness. Cotton and wool were chosen as the fabric substrates in this study due to their relatively widespread use in consumer products and natural dye research.
The persimmon dye used was 100% fermented astringent persimmon juice powder acquired from Bauhaus of Forest (Japan). The mordant used was reagent-grade crystalline ferrous sulfate heptahydrate (FeSO4·7H2O) from Fisher Scientific (Rochester, NY). Ferrous sulfate was chosen as a mordant because of its widespread use and a review of mordants used by other researchers in the subject. For example, in Yi and Cho’s (2008) paper, ferrous sulfate provided good results for the majority of the tested dyes, suggesting that persimmon dye would benefit from its inclusion during dyeing. Yi and Shamey (2015) also achieved good color strength of persimmon-dyed cotton when using ferrous sulfate mordant, providing further evidence for ferrous sulfate’s suitability as a mordant for persimmon dye.
Dyeing Procedure
Cotton and wool fabrics were dyed using a Datacolor Ahiba Nuance ECO-B dyeing machine. The dyeing machine was set to rotate the dye canisters at 30 rpm and to heat the canisters to 100°C. The dye bath’s liquor ratio was 1:50. Because the colorant of tannin stored in the persimmon juice powder is not significant, the dye concentrations tested were 50%, 100%, and 200% on weight of fabric (wof). These concentrations were higher than typical ones used in the textile dyeing industry. The high concentrations were expected to magnify the scale of color differences so that the differences were measurable. At each concentration, the dyeing was carried out for 30, 45, and 60 min.
Mordanting treatment (FeSO4·7H2O) was carried out using pre-, meta-, or postmordanting. Mordant concentration was 5% wof. Cotton and wool samples were also dyed without mordant to provide control samples. Premordanted samples were treated in a mordant bath before dyeing. Fabric samples were introduced into the mordanting solution (water and iron) at room temperature and loaded into the dyeing machine. After 60 min of mordanting at boil, samples were thoroughly squeezed and placed into a persimmon dye bath containing water and dissolved dye powder. After dyeing, samples were rinsed and air dried. Postmordanted samples were dyed in the persimmon dye bath before being treated in the mordant bath. After dyeing, samples were thoroughly squeezed and placed into the mordanting bath for 60 min at boil. Samples were rinsed and air dried after mordanting. Meta-mordanted samples were concurrently dyed and mordanted in one bath. Nonmordanted samples were dyed without mordanting treatment. Each dyeing, mordanting, and time length procedure was replicated 3 times. The mordanting procedure, dye concentration, and dyeing time combination that yielded the highest color strength was then used to dye samples for American Association of Textile Chemists and Colorists (AATCCs) colorfastness testing and FTIR analysis.
Colorfastness Testing
AATCC standard colorfastness tests were used to evaluate persimmon dye’s performance on the test fabrics. Colorfastness to laundering was evaluated using AATCC Test Method 61-2003—1A (colorfastness to laundering, home, and commercial: accelerated), colorfastness to perspiration was evaluated using AATCC Test Method 15-2002, and colorfastness to crocking was evaluated using AATCC Test Method 116-2005. Change in shade was evaluated using the AATCC Gray Scale for Color Change, and staining was evaluated using the AATCC Gray Scale for Staining (2006).
Color Strength and Appearance Evaluation
Color strength and appearance were evaluated using a HunterLab ColorQuest XE® diffuse/80 spectrophotometer. The spectrophotometer was operated with a 1-in. diameter specimen-viewing aperture in reflectance—specular included mode. Each sample was scanned 3 times and rotated 90° between each scan to minimize error and increase accuracy. The data recorded from the scans consisted of K/S values and CIE L* a* b* values based on a standard illuminant. Dyed samples from the dyeing experiment were scanned after air drying. Colorfastness-tested samples were evaluated using the spectrophotometer immediately after AATCC Gray Scale evaluation to minimize change in the samples’ temperature and humidity. Change in K/S and L* a* b* values before and after colorfastness testing was analyzed for statistical significance. This was done using the paired t-test because each sample served as the control and treatment sample (Ott & Longnecker, 2010). All statistical tests were conducted using the statistics software R (version 3.3.0; R Core Team, 2013) at a significance level of p ≤ .05.
Chemical Composition Analysis
Dye performance on cotton and wool was further analyzed using FTIR with advanced attenuated total reflectance (Nicolet iS50 FT-IR Spectrometer). Scans were taken using a 400 to 4,000 cm−1 spectrum, 16 coaddition scans, and 4 cm−1 resolution. Data were generated and analyzed using OMNIC™ Spectra software (Thermo Scientific, USA). Chemical composition analysis using FTIR was conducted to characterize the dyed fabrics and dye and determine whether the dye was chemically bonding to the fabrics.
Results and Discussion
Color Strength and Color Appearance Analysis
Undyed cotton and wool fabrics were evaluated for their color strength and color appearance indicated by the K/S and L* a* b* values shown in Table 1. Undyed wool fabric had a much more yellow (+b* = 7.547) appearance, slightly greener (−a* = −1.532) appearance, and higher initial K/S (0.44) value than undyed cotton fabric. Wool’s slight coloration was expected because the only treatment done to the wool used in this work was carbonization. Carbonization only removes vegetable matter that derives from the original fleece, so some natural color was still present.
CIELAB L*a*b* Values for Persimmon-Dyed Cotton and Wool Fabrics Mordanted Using Different Methods.
The K/S values of dyed cotton and wool samples are shown in Figures 1 and 2, respectively. All K/S and L* a* b* readings were taken at the peak wavelength, 400 nm. Wool samples’ K/S was significantly higher than the cotton samples’ K/S under all dyeing conditions. Cotton and wool samples dyed using postmordanting, 200% dye concentration, and 60 min dyeing length exhibited the highest K/S values (6.8 and 20.5, respectively). Therefore, that dyeing procedure was used to dye samples for all following AATCC colorfastness tests.
Cotton samples’ K/S after dyeing using (a) no mordant, (b) premordanting, (c) meta-mordanting, and (d) postmordanting. Standard error bars are included.
Wool samples’ K/S after dyeing using (a) no mordant, (b) premordanting, (c) meta-mordanting, and (d) postmordanting. Standard error bars are included.
Effect of dye concentration and dyeing time
The fabrics’ color strength generally increased when dye concentration increased at a constant dyeing time. For example, increasing concentration from 50% to 200% on postmordanted cotton and wool samples increased cotton’s K/S by 65% and wool’s K/S by 37% on average (Figures 1d and 2d, respectively). The fabrics’ color strength also generally increased with longer dyeing times. For example, increasing dyeing time from 30 to 60 min on postmordanted cotton and wool samples increased cotton’s K/S by 9% and wool’s K/S by 55% on average (Figures 1d and 2d, respectively). Similar results regarding increased concentration were demonstrated on multiple natural dyes, such as cochineal, indigo, and turmeric in Yi and Cho’s (2008) study. Compared to dye concentration, dyeing time usually affected K/S less in this study. However, the impact of those variables varied depending on the mordanting procedure. Meta-mordanted samples’ K/S was affected more by time increase (Figures 1c and 2c), but premordanted samples’ K/S was affected more by concentration increase (Figures 1b and 2b). Because dyeing is generally a transfer of dye from the solution to the fiber resulting in a reduction in the concentration in solution, more dye molecules would diffuse to the fiber when the initial concentration in the dye bath is high due to a large concentration gradient. Also, more dye molecules would be deposited on the fiber, when more diffusion time is given at dyeing. Large K/S indicates deep color, as a result of more dye molecules on the fibers.
Effect of mordanting procedure
Color strength on the cotton and wool fabrics increased significantly when a mordant was used. Cotton samples’ K/S increased from 1.22 without a mordant to a maximum of 6.8 (after postmordanting; Figure 1d). Similarly, wool samples’ K/S increased from 5.0 without a mordant to a maximum of 20.5 (after postmordanting; Figure 2d). Another important result to note was that for all dyeing conditions, meta-mordanted wool and cotton samples became much stiffer with a rougher hand than any other samples. Dyeing using meta-mordanting also resulted in the presence of clumps of black gel residue on the fabric and dye container surface. The presence of a gel residue was also discovered in previous studies (Rahim & Kassim, 2008). It was suggested that a localization of the tannin due to the mordant resulted in tannin precipitation on the fabric surface. Much of the gel was removed during rinsing, but some stayed attached to the fabric, appearing as a black coloration. Therefore, meta-mordanting, especially when dyeing wool fabric, is not recommended.
The mordanting procedure used also impacted the samples’ color appearance greatly. The average CIE L* a* b* values for the samples with the highest K/S per mordanting procedure per fabric are shown in Table 1. The L* a* b* values demonstrate how the samples’ appearances were altered based on mordanting procedure and fabric used. All nonmordanted samples yielded a light brown–orange coloration. Postmordanted samples yielded medium gray (L* a* b* values closer to zero) on cotton samples and dark purple–gray (lowest L* and b* values) on wool samples. Meta-mordanted wool and cotton yielded light gray on cotton samples and medium gray on wool samples, which corresponded with their K/S values being second highest out of all mordanting methods. Interestingly, wool samples yielded darker colors (higher K/S value) than cotton samples dyed when using the same dyeing procedure for both fabrics.
Colorfastness
Colorfastness fabric samples were prepared using postmordanting, 200% dye concentration, and 60 min dyeing time because those conditions resulted in the highest color strength for both fabrics. The K/S and L* a* b* values for cotton and wool before and after colorfastness testing are compared in Figure 3. The K/S and L* a* b* values were different than the results obtained from pilot dyeing because the dye was from a different manufacturing batch. Poor substantivity and fastness properties are often found in natural dyes for wool and cotton and can be improved if the fabric is first treated with a solution containing mordant, such as a salt of iron, copper, or tin (Broadbent, 2001). Metallic mordants improve the fixation and fastness properties of dyes lacking substantivity for natural fibers. When the premordanted fabric was soaked in a bath of a suitable natural dye, the dye penetrated into the fibers and reacted with the metal ions present in the fibers. The dye bonded the mordant to form a stable dye–metal complex. This reaction decreased the water solubility of the dye, so the color was less likely to bleed out on washing, resulting in better colorfastness in dyed fabrics.
K/S and L*a*b* values before and after laundering and perspiration testing on cotton (a, b) and wool (c, d).
The AATCC Gray Scale ratings for cotton and wool fabrics’ colorfastness testing are shown in Table 2. Both dyed cotton and wool samples’ colorfastness performance varied depending on the test performed, although they performed acceptably (3 or higher) in most tests. The color strength and color appearance of both cotton and wool changed significantly during laundering. These changes in K/S and L* a* b* of cotton and wool after laundering are shown in Figure 3a and c, respectively. Samples’ redness (+a*), yellowness (+b*), and darkness (decrease in L*) increased at a statistically significant level. Yi and Cho (2008) increased persimmon-dyed fabrics’ color strength using sunlight, so it is possible that the increase in the current study was due to the 40°C laundering temperature. Perspiration testing yielded a significant decrease in cotton samples’ K/S and significant changes in color appearance as shown in Figure 3b. Cotton samples’ redness (+a), yellowness (+b), and lightness (increased L*) increased at statistically significant levels. In summary, the dyed cotton received average or above-average ratings except in color change from laundering (2–3) and wet crocking staining (2–3).
American Association of Textile Chemists and Colorists (AATCCs) Gray Scale Evaluation for Colorfastness of Persimmon Dyed Cotton and Wool Samples.
Wool samples’ redness (+a*) and yellowness (+b*) increased at statistically significant levels after laundering as shown in Figure 3c. However, wool samples’ L* values did not change at a statistically significant level. The wool samples performed similar to cotton samples in that the color strength increased significantly after laundering. Nevertheless, the wool samples’ L* a* b* value change was 35% less on average than the cotton fabric samples. The changes in K/S and L* a* b* values after the wool samples underwent perspiration testing are shown in Figure 3d. The wool samples changed little after perspiration testing, and only the wool samples’ yellowness (+b*) increased at a statistically significant level. Overall, persimmon dye performed well on wool fabric. It received above-average to excellent ratings except in laundering (3) and wet crocking (3).
It is important to note that some of wool’s higher color strength could be attributed to fiber diameter. It is possible that large diameter fibers of wool usually have higher K/S values than fine fibers of cotton at a given amount of dye. Dye performance to laundering was fairly similar for the wool and cotton fabrics. Fabric samples became redder for both fabrics, but cotton’s redness increased much more than wool’s. Additionally, cotton samples appeared darker (decreased L*), while wool’s L* did not change significantly. The wool fabric’s color strength and color appearance changed 15% less on average compared to the cotton fabric after laundering testing. Both fabrics performed similarly during laundering overall, although with wool performing only slightly better in regard to AATCC ratings. Persimmon-dyed wool received ratings one scale higher than cotton for dry and wet crocking, suggesting the color on wool from persimmon dye is preserved better in situations where fabric-on-fabric abrasion occurs. Dye colorfastness to perspiration varied significantly between wool and cotton. Cotton samples’ K/S and L* a* b* values changed at significant levels, whereas only the wool samples’ b* value changed significantly. This significant difference can be seen when comparing Figure 3a against 3c and Figure 3b against 3d. Cotton samples became significantly lighter and appeared more orange (+a*, +b*). Additionally, wool received an AATCC Gray Scale rating of 4 compared to cotton’s rating of 3. These differences suggest that persimmon dye’s colorfastness to perspiration is better on wool than on cotton. It may be because wool fibers usually show better resistance to acids than cotton (Kadolph, 2007). The change in cotton fibers due to acids may aid persimmon dye’s poor colorfastness on cotton. Another possible explanation is that the dye performance on cotton is less effective in producing mordant–dye complex in the cotton fibers.
Wool samples yielded a much higher K/S than cotton for all tested dyeing procedures. The biggest difference occurred when wool generated an 822% higher K/S than cotton using premordanting, 200% concentration, and 45 min length for each fabric. Postmordanting, 200% concentration, and 60 min dyeing time yielded a 201% higher K/S on wool compared to cotton. Wool contains about 820 mmol kg−1 of amino groups. Under acidic conditions, some of these will accept protons to form ammonium ions. Persimmon powders contain tannins, which consist of tannic acid. The negatively carboxylate groups in the tannic acid easily bond to positively charged sites of amine groups in wool. Therefore, a greater dye uptake was found in wool fabrics than cotton fabrics.
Chemical Composition Analysis
Based on the aforementioned reactions (wool fabric’s increase in stiffness after meta-mordanting and the dye’s color change depending on mordanting order), chemical composition analysis using FTIR was conducted to characterize the persimmon dye and dyed fabrics to determine whether the dye was chemically bonding to the fabrics.
Persimmon dye powder
Persimmon powders contain tannins. The FTIR spectra (Figure 4a) showed peaks similar to other materials containing tannins. Peaks at 1,608.28 cm−1, 1,535.64 cm−1, and 1,444.70 cm−1 likely indicate the presence of aromatic rings. The high-intensity peak at 1,608.28 cm−1 could indicate a C–C stretch corresponding with interflavonoid linkages. The single peak at 1,535.64 cm-1 suggests that the persimmon tannin consists mainly of procyanidin (Oo, Kassim, & Pizzi, 2009). The single 1,206.13 cm−1 peak is likely due to C–H stretching, and the peaks at 828.42 cm−1 and 763.85 cm−1 are likely from C–H vibrations in the aromatic rings (Kim & Kim, 2003). Finally, peaks at 1,146.151 cm−1, 1,104.53 cm−1, and 1,032.99 cm−1 are suggested to be due to aromatic C–H bending (Fernandez & Agosin, 2007).
Fourier transform infrared spectra for (a) undyed and postmordanted cotton and persimmon dye powder, (b) postmordanted, laundering-tested, and perspiration-tested cotton. Peak intensity at 1,630.67 cm−1 increased after dyeing compared to undyed cotton fabric.
Cotton
The FTIR spectrum for persimmon dye powder and undyed cotton (a) compared to tested cotton (b) is shown in Figure 4. Postmordanted cotton’s spectrum is included in Figure 4a and b for ease of comparison with the other spectra. As shown in Figure 4a, the spectrum of the undyed cotton showed characteristic water adsorption (1,641.83 cm–1) and cellulose characteristic peaks (Garside & Wyeth, 2003). Compared to undyed cotton’s FTIR spectrum, the dyed cotton FTIR spectra showed a peak shift from 1,641.83 cm–1 to between 1,630.67 cm–1 and 1,617.97 cm–1 depending on mordanting procedure (Figure 4b). This shift brings the peak more in line with the 1,608.28 cm–1 peak in the dye powder. The 1,630 to 1,640 cm–1 range corresponds with water in cellulose and the peak’s intensity increased, suggesting an increase in water absorbed in the cotton. This may imply cotton’s hydrophilicity increases due to the persimmon dye. This peak shift was unaffected by laundering and perspiration testing, suggesting the change was resistant to those conditions (Figure 4b). Other than the peak shift at 1,641.83 cm–1, little chemical structure change took place in cotton during any dyeing procedure, suggesting persimmon dye forms minimal chemical bonds with cotton fabric. This is clearly demonstrated in Figure 4; all dyed and tested cotton spectra appear roughly the same as the undyed cotton except for the slight peak shift.
Wool
The FTIR spectrum for persimmon dye powder and undyed wool (a) compared to tested and meta-mordanted wool (b) is shown in Figure 5. Postmordanted wool’s spectrum is included in Figures 5a and b for ease of comparison with the other spectra. The spectrum of the undyed wool showed characteristic amide I, II, and III peaks at 1,641.82 cm−1 (C=O stretching), 1,529.81 cm−1 (N–H bending, C–N stretching), and 1,077.23 cm−1 (C–N stretching, N–H bending), respectively (Khan et al., 2012). The peak at 1,390.84 cm−1 is suggested to be from the presence of an amino acid (COO−). Wool’s peaks at 1,641.82 cm−1 and 1,529.81 cm−1 associated with amide I and II bands decreased in intensity after dyeing as shown in Figure 5a. Interestingly, the peak at 1,390.84 cm−1 changed intensity depending on the mordanting procedure. The peak’s intensity on undyed wool was 0.0457 versus 0.0291 on postmordanted wool and 0.0501 on meta-mordanted wool. The increase in peak intensity on meta-mordanted wool could be due to an interaction between the amino acid present and the mordant that reacted with the dye and was still present on the surface of the material. The decrease in peak intensity on postmordanted wool was likely due to persimmon dye that was present on the fiber. This may suggest that this amino acid group is easily affected by surface treatments. After undergoing laundering testing, the peak at 1,390.84 cm−1’s intensity returned to 0.0401 compared to its original 0.0457 shown in Figure 5b. The impermanent intensity decrease at 1,390.84 cm−1 suggests a weak interaction (Yu & Zhang, 2013). It is important to note that Kourkoumelis, El-Gaoudy, Varella, and Kovala-Demertzi (2012) suggested strong bonds can form when a dye and a fabric show similar peaks on FTIR spectra. Wool has peaks at 1,529.81cm−1 and 1,451.11 cm−1, which correspond closely to persimmon dye’s peaks at 1,535.64 cm−1 and 1,444.70 cm−1. This could help explain wool’s greater affinity to persimmon dye compared to cotton, as cotton shared no similar peaks with the persimmon dye. Meta-mordanted wool exhibited a peak shift from 1,077.23 cm−1 to 1,040.47 cm−1 as shown in Figure 5b. A peak near 1,040.47 cm−1 is suggested to be due to the bonding of the ferrous sulfate mordant (Khan et al., 2012). This could explain the appearance of dark spots and change in flexibility as discussed in the previous section and could suggest the ferrous sulfate has chemically bonded to the fabric. Meta-mordanted wool also shows a peak intensity increase at 1,390.84 cm−1 from 0.0457 to 0.0501. This might be due to the reaction between the persimmon dye and ferrous sulfate. The perspiration-tested FTIR spectrum is shown in Figure 5b. Little difference appeared between postmordanted and perspiration-tested samples, suggesting perspiration has little chemical effect on the wool samples.
Fourier transform infrared spectra for (a) undyed and postmordanted wool and persimmon dye powder, (b) postmordanted, laundering-tested, and perspiration-tested wool. Peak intensity at 1,390.84 cm−1 changed depending on dyeing technique, and a new peak appeared at 1,040.47 cm−1 after meta-mordanting.
Conclusions
We discovered that good color strength can be imparted using persimmon dye on wool and cotton fabrics. Color strength increased with increased dye concentration, dyeing time, and addition of mordant for both fabrics. Postmordanting produced better dye performance and K/S values for both fabrics than premordanting and meta-mordanting. Wool can achieve much higher (201– 822%) K/S values than cotton when comparing dyeing techniques. Additionally, persimmon dye demonstrated acceptable colorfastness performance (rating of 3 and higher) on both substrates. Wool also retained the dye better as demonstrated by a lower percentage change in color strength than cotton after laundering and colorfastness (15% and 68% less, respectively). Finally, FTIR analysis on dyed and tested samples showed that the persimmon dye formed few or minimal bonds with both fabrics’ surfaces, denoting minimal impact on chemical and physical properties of dyed cotton and wool fabrics. Observations of dye performance and chemical analysis on dyed fabrics are helpful in exploring the opportunity of using persimmon dye as a natural dye for a sustainable textile dyeing industry, especially in the case of dyeing natural fibers.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was financially supported by faculty development funds at Colorado State University and Rockywoods Fabrics. The authors give thanks to Dr. Hongyi Liu for his great help on discussing the results.