{"id":3014,"date":"2011-03-05T23:43:07","date_gmt":"2011-03-06T06:43:07","guid":{"rendered":"http:\/\/www.denimsandjeans.com\/denim\/manufacturing-process\/indigo-dyeing-methods-engineering-color-wash-fastness-and-fashion-effects\/"},"modified":"2013-08-03T01:09:55","modified_gmt":"2013-08-03T08:09:55","slug":"indigo-dyeing-methods-engineering-color-wash-fastness-and-fashion-effects","status":"publish","type":"post","link":"https:\/\/www.denimsandjeans.com\/recovery\/denim\/manufacturing-process\/indigo-dyeing-methods-engineering-color-wash-fastness-and-fashion-effects\/3014","title":{"rendered":"Indigo Dyeing Methods &ndash; Engineering Color, Wash Fastness And Fashion Effects"},"content":{"rendered":"<p><em>This is a guest post by Harry Mercer. This is a very technical description \u00e2\u20ac\u201c read on if you are technically oriented..<\/em><\/p>\n<p>Here are given some important dyeing processes related to indigo dyeing \u00e2\u20ac\u201c specially on Rope Dyeing .<\/p>\n<h2>Pre Treatment<\/h2>\n<p>Pre-treatment is conducted in the 1st tank. The most common pre-treatments are :<\/p>\n<h3><font color=\"#0080ff\"><font color=\"#000000\">1.<\/font>&#160; Sulfur bottoming<\/font><\/h3>\n<h3><font color=\"#0080ff\"><font color=\"#404040\">2.<\/font>&#160; Scouring with sodium hydroxide<\/font><\/h3>\n<h3><font color=\"#0080ff\"><font color=\"#404040\">3.<\/font>&#160; Causticizing or Mercerizing<\/font> <\/h3>\n<h2><em><font color=\"#808080\">Pre- Treatment : Sulphur Bottoming<\/font><\/em> <\/h2>\n<p>\u00e2\u20ac\u00a2The purpose of sulfur bottoming was to:<\/p>\n<ul>\n<li>Originally to produce a <strong>dark shade<\/strong> on denim using less Indigo for lower costs <\/li>\n<li>In the U.S. sulfur bottoms were dyed using a combination of <strong>blue and black dyes <\/strong><\/li>\n<li>In denim operations outside the U.S. the bottom is normally dyed with sulfur black <\/li>\n<\/ul>\n<h2><font color=\"#808080\"><em>Pre \u00e2\u20ac\u201c Treatment : Cotton Scouring<\/em><\/font> <\/h2>\n<p>Cotton fibers contain impurities like waxes, pectins and minerals that will interfere with Indigo dyeing and result in streaks.-Sodium hydroxide at low concentrations (&lt;5%) are applied at high temperatures (&gt;85 C) in order to remove impurities and melt natural cotton waxes.<\/p>\n<h2><em><font color=\"#808080\">Pre \u00e2\u20ac\u201c Treatment : Causticizing<\/font><\/em> <\/h2>\n<ul>\n<li>Causticizing generally refers to using sodium hydroxide at below Mercerizing concentrations (&lt;18%). <\/li>\n<li>Cold causticizing of cotton yarn results infaster Indigo dye fading from laundryabrasion, darker Indigo color with the same % of Indigo and unique washdowns. <\/li>\n<li>Hot causticizing improves colorfastness <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Pre \u00e2\u20ac\u201c Treatment : Mercerizing<\/font><\/em> <\/h2>\n<p>Mercerizing is the use of strong sodium hydroxide (18-30%) to swell surface fibers.<\/p>\n<p><strong>Caution:<\/strong><\/p>\n<ul>\n<li>When using strong sodium hydroxide it is important to remove all of it. <\/li>\n<li>If sodium hydroxide is on the yarn as it enters the Indigo tanks, the yarn color will change. <\/li>\n<li>Concentrations of sodium hydroxide <strong>more than 18% are not a solution, but a gel<\/strong> and are difficult to remove. <\/li>\n<li>Mercerized yarns are <strong>more ring-dyed<\/strong> and dye more darkly than non-Mercerized. <\/li>\n<li>Mercerizing is normally conducted at<strong> low temperatures<\/strong>, but hot Mercerizing can be employed for a more abraded appearance after garment laundering. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Indigo Dyeing<\/font><\/em> <\/h2>\n<ul>\n<li>Indigo dyeing is unique and because of the complex chemical reactions should be correctly viewed a a form of chemical engineering. <\/li>\n<li>Only Indigo dyeing requires multiple dye applications for a dark shade. <\/li>\n<li><strong>Color consistency of Indigo in recent decades has been unsatisfactory as a result of machine designs<\/strong> that do not apply basic principles of fluid mechanics properly and unstable dye mixes. <\/li>\n<li>Commonly, a single dye lot will have between 8 and 15 visually different shades from beginning to end and also have shade differences from one side to the other. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Indigo Dyeing Methods<\/font><\/em> <\/h2>\n<p><a href=\"http:\/\/morrisontexmach.com\/welcome.cfm\" target=\"_blank\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"Spectrum_single_thread\" border=\"0\" alt=\"Spectrum_single_thread\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/spectrum-single-thread.jpg\" width=\"454\" height=\"169\" \/><\/a><\/p>\n<ul>\n<li>Indigo dyeing follows the same basic steps regardless of machine design. <\/li>\n<li><strong>Scour or dye bottoming<\/strong> in a heated tank, <\/li>\n<li>washing tanks, dyeing(1-20),a heated tank for topping (optional) and wash tanks. <\/li>\n<li>In different areas of the world,the same color is produced using<strong> 1.8, 2.0 or 4% Indigo<\/strong> depending on dyeing method. <\/li>\n<li><\/li>\n<\/ul>\n<p>&#160;<\/p>\n<p><a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image.png\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"indigo dyeing methods\" border=\"0\" alt=\"indigo dyeing methods\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image-thumb.png\" width=\"454\" height=\"171\" \/><\/a><\/p>\n<p>&#160;<\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Dark Indigo(1.8%)<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. 15% caustic cold            <br \/>2.Wash 60\u00c2\u00b0C             <br \/>3.Wash 60\u00c2\u00b0C             <br \/>4. Wash cold             <br \/>Drying cylinders hot             <br \/>Steamer cold             <br \/>Boxes 5-12 Indigo             <br \/>Steamer cold             <br \/>13.Wash 50\u00c2\u00b0C             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16.Wash 50\u00c2\u00b0C \/Softener<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Stock Mix 80 g\/l Indigo Pure 100 g\/l 50% Caustic 70 g\/l Hydro powder. <\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p><strong>Chemical Feed 120 g\/l 50% caustic 60g\/l Hydro powder Feed 1.4 liters per minute<\/strong><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><em><font color=\"#808080\">Dark Indigo Color<\/font><\/em> <\/h2>\n<ul>\n<li>This was an example of a typical method used in the U.S. for a very dark shade. <\/li>\n<li>In order to produce the same depth of color as 1.2% in the U.S., in Latin America 2.0% is used and in Asia from 2.4 to 2.8%. <\/li>\n<li>The U.S. method results in more surface (ring dyeing), which loses color faster. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Darkest Indigo Shades<\/font><\/em><\/h2>\n<ul>\n<li>Very dark shades of Indigo are in demand currently around the world. <\/li>\n<li>Many companies use 4% or more Indigo on weight of yarn, which is expensive. <\/li>\n<li><strong>2% Indigo will produce the same depth if low levels of caustic are used(0-0.4%)<\/strong> <\/li>\n<li>For dark Indigo that does not lose color 2% applied normally, with an Indigo bottom. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Light Indigo Shades<\/font><\/em> <\/h2>\n<ul>\n<li>Dyeing Indigo in light shades results in a<strong> <\/strong>sky-blue impossible with any other dye. <\/li>\n<li>This is useful for <strong>shirting fabrics<\/strong> that are&#160; not strong enough for stonewashing,&#160; bleaching or cellulase treaments. <\/li>\n<li><strong>Special procedures are necessary in order to avoid colorfastness problems.<\/strong> <\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image1.png\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"indigo dye baths\" border=\"0\" alt=\"indigo dye baths\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image-thumb1.png\" width=\"454\" height=\"171\" \/><\/a><\/p>\n<p>&#160;<\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Light Indigo 0.4%<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. 4% caustic 90\u00c2\u00b0C            <br \/>2.Wash 60\u00c2\u00b0C             <br \/>3.Wash 60\u00c2\u00b0C             <br \/>4. Wash 60\u00c2\u00b0C             <br \/>Bypass drying cylinders             <br \/>Bypass steamer             <br \/>Close off boxes 5-8             <br \/>Boxes 9-12 Indigo             <br \/>13. Wash 50\u00c2\u00b0C             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16.Wash 50\u00c2\u00b0C\/softener<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Control Of Sulphur Bottoming <\/h2>\n<ul>\n<li>The typical methods used for dyeing sulfur bottoms result in denim shade differences. <\/li>\n<li>When applied as light colors, sulfur dyes should be dyed at <strong>temperatures &lt;60 C,<\/strong> <\/li>\n<li>If dextrin reducing agents are used, <strong>which require 85 C<\/strong>, there will be variation. <\/li>\n<li>Sulfur bottoms are an exception to the normal pH for sulfurs(11), requiring 12. <\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image2.png\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"indigo machine\" border=\"0\" alt=\"indigo machine\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image-thumb2.png\" width=\"454\" height=\"171\" \/><\/a><\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Sulfur Bottom<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. Pad sulfur(cold)            <br \/>Steamer hot             <br \/>2.Wash cold             <br \/>3.Wash 50\u00c2\u00b0C             <br \/>4.Wash 50\u00c2\u00b0C             <br \/>Boxes 5-10 Indigo             <br \/>11. Indigo or wash 50\u00c2\u00b0C             <br \/>12. Indigo or wash 50\u00c2\u00b0C             <br \/>Bypass steamer             <br \/>13. Wash 50\u00c2\u00b0C             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16.Wash 50\u00c2\u00b0C or softener<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Sulphur Topping <\/h2>\n<ul>\n<li>In topping the sulfur dye is applied after the Indigo dyeing. <\/li>\n<li><strong>Sulfur topping permits much darker color than a sulfur bottom<\/strong>, <strong>but is duller.<\/strong> <\/li>\n<li>Sulfur topping colors include black, blue-black, yellow brown and green. <\/li>\n<li>Sulfur toppings are used to produce slub appearances in normal yarn. <\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image3.png\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"indigo dyeing machine\" border=\"0\" alt=\"indigo dyeing machine\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image-thumb3.png\" width=\"454\" height=\"167\" \/><\/a><\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\"><strong>Sulfur Top<\/strong><\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. Pre-wet 2% caustic 90\u00c2\u00b0C            <br \/>2.Wash 60\u00c2\u00b0C             <br \/>3.Wash 60\u00c2\u00b0C             <br \/>4. Wash cold             <br \/>By pass drying cylinders             <br \/>Bypass steamer             <br \/>Boxes 5-10 Indigo             <br \/>11. Wash 60\u00c2\u00b0C             <br \/>12. Pad sulfur topping             <br \/>Steamer hot             <br \/>13. Wash cold             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16.Wash 50\u00c2\u00b0C\/Softener<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><em><font color=\"#808080\">Reactive Dyes in Indigo Dyeing<\/font><\/em><\/h2>\n<ul>\n<li>Reactive dyes can be applied on specially-Designed Indigo machines. <\/li>\n<li><strong>Small 150 liter boxes are inserted inside the larger dye tanks for Indigo and sulfur.<\/strong> <\/li>\n<li>Steamers, drying units near the front of the machine and high-quality dye padders are required for quality dyeing. <\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image4.png\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"image\" border=\"0\" alt=\"image\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image-thumb4.png\" width=\"454\" height=\"141\" \/><\/a>&#160;<\/p>\n<p>&#160;<\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Pad-Dry Chempad- Steam Reactives<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. Pre-scour wetter plus chelate 90\u00c2\u00b0C            <br \/>2.Wash 50\u00c2\u00b0C             <br \/>3. Pad monochlortriazine dye cold, neutral pH             <br \/>Drying cylinders hot             <br \/>Pad caustic in salt brine             <br \/>Steamer hot             <br \/>Bypass boxes 5-10             <br \/>11. Soap 90\u00c2\u00b0C             <br \/>12. Soap 90\u00c2\u00b0C             <br \/>Steamer hot             <br \/>13. Wash 60\u00c2\u00b0C             <br \/>14. Wash 60\u00c2\u00b0C             <br \/>15. Wash cold             <br \/>16.Wash cold\/softener<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&#160;<\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Pad Steam Reactive Topping<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. Pre-wet 10% caustic 90\u00c2\u00b0C            <br \/>2.Wash 60\u00c2\u00b0C             <br \/>3.Wash 60\u00c2\u00b0C             <br \/>4. Wash cold             <br \/>By pass drying cylinders             <br \/>Bypass steamer             <br \/>Boxes 5-10 Indigo             <br \/>11. Wash 60\u00c2\u00b0C             <br \/>12. Pad Dichorotriazinyl cold with bicarbonate             <br \/>Steamer hot             <br \/>13. Wash cold             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16. Wash 50\u00c2\u00b0C \/ softener<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><em><font color=\"#808080\">Vat Dyeing<\/font><\/em><\/h2>\n<ul>\n<li>Indigo and sulfurs are types of vat dyes. <\/li>\n<li>In <strong>non-denim cotton dyeing, another class of vats, anthaquinoids are used<\/strong> to produce a full range of colors that are colorfast. <\/li>\n<li>Some of these vat dyes can be blended with Indigo or applied using standard procedures on specially designed machines. <\/li>\n<\/ul>\n<p>&#160;<a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image3.png\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"indigo dyeing machine\" border=\"0\" alt=\"indigo dyeing machine\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/image-thumb3.png\" width=\"454\" height=\"167\" \/><\/a><\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\">\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Pad-Dry Chempad Vats<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. Pre-wet 4% caustic 90\u00c2\u00b0C            <br \/>2.Wash 60\u00c2\u00b0C             <br \/>3. Pad vat dye cold             <br \/>Drying cylinders hot             <br \/>4. Chempad caustic\/hydro cold             <br \/>Steamer hot             <br \/>Bypass boxes 5-10             <br \/>11. Wash 60\u00c2\u00b0C             <br \/>12. Oxidize             <br \/>13. Soap with anti-oxidant             <br \/>Steamer hot             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16. Wash 50\u00c2\u00b0C \/ softener<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&#160;<\/p>\n<table border=\"2\" cellspacing=\"0\" cellpadding=\"2\" width=\"400\" bgcolor=\"#faf8cc\"><strong><\/strong>&lt;&gt;&lt;&gt;&lt;&gt;&lt;&gt;&lt;\/&gt; &lt;\/&gt;&lt;\/&gt;&lt;\/&gt;<\/p>\n<tbody>\n<tr>\n<td valign=\"top\" width=\"200\">\n<p><strong>Pad-Dry Chempad Steam Vat Bottom<\/strong><\/p>\n<\/td>\n<td valign=\"top\" width=\"200\">\n<p>1. Pre-wet 4% caustic 90\u00c2\u00b0C            <br \/>2. Wash 60\u00c2\u00b0             <br \/>3. Pad vat dye cold             <br \/>Drying cylinders hot             <br \/>4. Chem-pad caustic\/hydro cold             <br \/>Steamer hot             <br \/>Boxes 5-10 Indigo             <br \/>11. Wash 60\u00c2\u00b0C             <br \/>12. Soap 90\u00c2\u00b0C             <br \/>Steamer hot             <br \/>13. Wash cold             <br \/>14. Wash 50\u00c2\u00b0C             <br \/>15. Wash 50\u00c2\u00b0C             <br \/>16. Wash 50\u00c2\u00b0C<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&#160;<a href=\"http:\/\/morrisontexmach.com\/welcome.cfm\" target=\"_blank\"><img loading=\"lazy\" decoding=\"async\" style=\"border-right-width: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\" title=\"2-1_indigo_washer\" border=\"0\" alt=\"2-1_indigo_washer\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2011\/03\/21-indigo-washer.jpg\" width=\"370\" height=\"288\" \/><\/a><\/p>\n<h2><em><font color=\"#808080\">Control Of Indigo Dyeing<\/font><\/em><\/h2>\n<p>The Indigo dyeing process begins with a concentrated mixture of Indigo, sodium hydroxide and reducing agent.&#160; <strong>This concentrated mixture (70-90 g\/L Indigo) is delivered by pipes to the Indigo dye tanks where the dye concentration is reduced to 1-4 g\/L <\/strong>for dyeing the cotton.<\/p>\n<h2><em><font color=\"#808080\">Dye Mixing Procedures<\/font><\/em> <\/h2>\n<ul>\n<li>Many denim companies find it difficult to control original and washed Indigo shades. <\/li>\n<li>The primary source of color differences is the instability and inconsistency of Indigo mixtures. <\/li>\n<li>As the concentration of reducing agent going to the dye machine changes, the color changes. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Uniform Indigo Mixtures<\/font><\/em> <\/h2>\n<ul>\n<li>For consistent Indigo dyeing, the mixture must have consistent concentrations of Indigo, sodium hydroxide and reducer from the top of the mixture to the bottom. <\/li>\n<li>The main cause of inconsistent Indigo mixtures relates to concentration levels. <\/li>\n<li>Instability of Indigo mixtures results from the decomposition of sodium hydrosulfite. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Consistency of Concentration<\/font><\/em> <\/h2>\n<ul>\n<li>There is a limit to the amount of any chemical that can be dissolved in water. <\/li>\n<li>When the limit of solubility of any chemical \u00e2\u20ac\u00a2In water is exceeded, precipitation occurs. <\/li>\n<li>Indigo mixes should not have more than 20% solids. At higher levels, chemicals and dye sink to the bottom of the tank. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Improving Dyeing Consistency<\/font><\/em><\/h2>\n<ul>\n<li>When reducing agent sinks to the bottom of the tank, there is a higher concentration&#160; than in the top of the tank. As the dye enters the machine, the higher concentration results in a lighter, greenercolor and as the dye from the top of the tank enters the machine, the color is darker and redder. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Dye Control In Feeding&#160; Tank<\/font><\/em> <\/h2>\n<ul>\n<li>Stirring the tank for 2 minutes will improve dye uniformity between top and bottom. <\/li>\n<li>To avoid settling of dye and chemicals the total solids should not exceed 20%. <\/li>\n<li>The \u00e2\u20ac\u0153glass plate\u00e2\u20ac\u009d test can be used to test concentrations of hydrosulfite in the top and bottom. If dye requires 50 seconds to oxidize, there is about 50 g\/L of reducer. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Buffers In Indigo Dyeing<\/font><\/em> <\/h2>\n<ul>\n<li><strong>Alkaline buffers have been used to make very dark shades of Indigo with as little as 1% dye<\/strong>, more ring-dyed, faster fading. <\/li>\n<li>Reductive buffers can eliminate color differences in Indigo-dyed denims and can reduce <strong>hydrosulfite use by 30-50%.<\/strong> <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Cold Dyeing Methods<\/font><\/em> <\/h2>\n<ul>\n<li>Sulfur colors can be dyed at low temperatures with specific buffers which produce more colorfast dyeings with no color variation. <\/li>\n<li>Cold dyeing methods have been used to blend Indigo and sulfurs, eliminating the need for separate bottoming and topping, while eliminating shade changes in both. <\/li>\n<\/ul>\n<h2><em><font color=\"#808080\">Special Dyeing Techniques<\/font><\/em><\/h2>\n<ul>\n<li>On rope ranges, space dyeing techniques can be simple and produce a wide range of special effects in denim. <\/li>\n<li>By dyeing part of the yarns with a sulfur top and leaving the rest un-dyed, many companies produce a slub appearance with regular yarns. <\/li>\n<li>Blending ring yarns of different sizes also produces a slub appearance. <\/li>\n<\/ul>\n<p id=\"guestposts\"><a href=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2010\/02\/image1.png\"><img loading=\"lazy\" decoding=\"async\" title=\"image\" border=\"0\" alt=\"image\" align=\"left\" src=\"http:\/\/www.denimsandjeans.com\/wp-content\/uploads\/2010\/02\/image-thumb1.png\" width=\"168\" height=\"132\" \/><\/a>This is a guest post by <strong>Harry Mercer<\/strong>. Mr. Mercer has 30 years experience in the denim business including 3 prominent U.S. denim companies<strong>.<\/strong> He is an expert colorist for measurement and color matching as well as textile testing. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>This is a guest post by Harry Mercer. This is a very technical description \u00e2\u20ac\u201c read on if you are technically oriented.. Here are given some important dyeing processes related to indigo dyeing \u00e2\u20ac\u201c specially on Rope Dyeing . Pre Treatment Pre-treatment is conducted in the 1st tank. The most common pre-treatments are : 1.&#160; [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[516],"tags":[607,481],"class_list":["post-3014","post","type-post","status-publish","format-standard","hentry","category-manufacturing-process","tag-guest-post","tag-indigo-dyeing"],"_links":{"self":[{"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/posts\/3014","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/comments?post=3014"}],"version-history":[{"count":0,"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/posts\/3014\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/media?parent=3014"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/categories?post=3014"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.denimsandjeans.com\/recovery\/wp-json\/wp\/v2\/tags?post=3014"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}