{"id":13872,"date":"2026-07-30T06:48:47","date_gmt":"2026-07-30T06:48:47","guid":{"rendered":"https:\/\/hlh-js.com\/?p=13872"},"modified":"2026-07-30T06:48:47","modified_gmt":"2026-07-30T06:48:47","slug":"color-consistency-and-dye-preparation-for-sls-parts-after-ceramic-bead-blasting","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/fr\/resource\/blog\/color-consistency-and-dye-preparation-for-sls-parts-after-ceramic-bead-blasting\/","title":{"rendered":"Color Consistency and Dye Preparation for SLS Parts After Ceramic Bead Blasting"},"content":{"rendered":"<script type=\"application\/ld+json\">{\n    \"@context\": \"https:\\\/\\\/schema.org\",\n    \"@graph\": [\n        {\n            \"@type\": \"Article\",\n            \"headline\": \"Color Consistency and Dye Preparation for SLS Parts After Ceramic Bead Blasting\",\n            \"description\": \"How ceramic bead blasting prepares PA12 and PA11 SLS parts for consistent dyeing \\u2014 covering the mechanism of dye absorption in nylon, why unblasted parts dye unevenly, bead size effect on colour depth, pre-dye blast protocols by colour target, timing from blast to dye bath, and \\u0394E measurement for batch colour consistency.\",\n            \"datePublished\": \"2026-07-27\",\n            \"dateModified\": \"2026-07-27\",\n            \"author\": {\n                \"@type\": \"Organization\",\n                \"name\": \"Jiangsu Henglihong Technology Co., Ltd.\",\n                \"url\": \"https:\\\/\\\/hlh-js.com\"\n            },\n            \"publisher\": {\n                \"@type\": \"Organization\",\n                \"name\": \"Jiangsu Henglihong Technology Co., Ltd.\",\n                \"url\": \"https:\\\/\\\/hlh-js.com\"\n            },\n            \"mainEntityOfPage\": {\n                \"@type\": \"WebPage\",\n                \"@id\": \"https:\\\/\\\/hlh-js.com\\\/resource\\\/blog\\\/color-consistency-and-dye-preparation-for-sls-parts-after-ceramic-bead-blasting\\\/\"\n            }\n        },\n        {\n            \"@type\": \"FAQPage\",\n            \"mainEntity\": [\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Why do unblasted SLS parts often look patchy or uneven after dyeing?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"As-built SLS parts have a heterogeneous surface: the semi-sintered skin that forms during the build has higher porosity and amorphous content than the fully sintered bulk material beneath it. This heterogeneity means dye penetrates faster and deeper in porous semi-sintered zones, producing darker patches, while dense fully sintered zones absorb dye more slowly and appear lighter. The result is a mottled, non-uniform colour that is clearly visible under uniform directional light. Ceramic bead blasting removes the heterogeneous semi-sintered skin and exposes a uniform, dense sintered surface that absorbs dye evenly \\u2014 eliminating the patchiness.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"What ceramic bead size should I use for pre-dyeing blast of PA12 SLS parts?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"For standard or dark colours (black, navy, dark grey), use ZS beads in the 0.15\\u20130.20 mm range to achieve Ra 6\\u201310 \\u00b5m \\u2014 this surface texture provides excellent dye penetration depth and gives deep, saturated colour. For medium colours (standard red, blue, green), use 0.12\\u20130.18 mm beads for Ra 5\\u20138 \\u00b5m. For light or pastel shades, use 0.08\\u20130.15 mm beads to achieve Ra 4\\u20137 \\u00b5m \\u2014 the smoother surface limits dye uptake depth and produces lighter saturation. Establish your target bead size by blasting reference coupons at two or three sizes and measuring colour with a spectrophotometer before committing to a production protocol.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"How long after ceramic bead blasting should I put SLS parts into the dye bath?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Transfer dry-blasted PA12 SLS parts to the dye bath within 2 to 4 hours of blasting. Parts exposed to ambient air for longer may accumulate fine dust or surface moisture that interferes with even dye uptake. If dyeing cannot begin within 4 hours, store blasted parts in a sealed clean bag until the dye bath is ready. For wet-blasted parts, dry in a forced-air oven at 60\\u201370\\u00b0C for 2\\u20134 hours first, then transfer to the dye bath within 1 hour of removing from the oven.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Can I control dye colour depth by changing the ceramic bead blast protocol?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Yes \\u2014 bead size is a direct control variable for colour depth. Finer beads produce lower Ra (smoother surface) which limits dye penetration depth, giving lighter, more pastel results. Coarser beads produce higher Ra (more texture) which increases dye uptake area and depth, giving deeper, more saturated colour. This relationship works independently of dye bath concentration and temperature, providing a process lever that can be used to fine-tune colour output without changing dye chemistry. If your standard black dye bath is producing consistently lighter-than-target output, switching from 0.10\\u20130.15 mm to 0.15\\u20130.25 mm beads will deepen the colour.\"\n                    }\n                }\n            ]\n        }\n    ]\n}<\/script>\n<style>\n.hlh-sls-c09{font-family:'Segoe UI',Arial,sans-serif;color:#2c3e50;line-height:1.82;max-width:860px;margin:0 auto;font-size:16px}\n.hlh-sls-c09 h1{font-size:2rem;color:#1a3456;font-weight:700;line-height:1.28;margin:0 0 .5rem}\n.hlh-sls-c09 h2{font-size:1.46rem;color:#1a3456;font-weight:700;margin:2.5rem 0 .72rem;padding-bottom:.4rem;border-bottom:3px solid #d86e18}\n.hlh-sls-c09 h3{font-size:1.14rem;color:#1a3456;font-weight:700;margin:1.75rem 0 .5rem}\n.hlh-sls-c09 h4{font-size:1rem;color:#d86e18;font-weight:700;margin:1.2rem 0 .35rem}\n.hlh-sls-c09 p{margin:0 0 1rem}.hlh-sls-c09 ul,.hlh-sls-c09 ol{margin:0 0 1rem 1.5rem;padding:0}.hlh-sls-c09 li{margin-bottom:.38rem}\n.hlh-sls-c09 a{color:#d86e18;text-decoration:none;border-bottom:1px solid rgba(216,110,24,.35)}.hlh-sls-c09 a:hover{color:#b85a10;border-bottom-color:#b85a10}\n.hlh-sls-c09 .meta{font-size:.85rem;color:#6b7c93;margin:.3rem 0 1.5rem}\n.hlh-sls-c09 .lead{font-size:1.07rem;color:#334f6e;line-height:1.9;padding:1.1rem 1.4rem;border-left:5px solid #d86e18;background:#fff8f2;border-radius:0 6px 6px 0;margin-bottom:2rem}\n.hlh-sls-c09 .back{display:flex;align-items:center;gap:.75rem;background:#f0f4f8;border:1px solid #c9d8e8;border-left:4px solid #1a3456;border-radius:0 6px 6px 0;padding:.72rem 1.2rem;margin-bottom:2rem;font-size:.9rem;color:#334f6e}\n.hlh-sls-c09 .back a{font-weight:600;color:#1a3456}.hlh-sls-c09 .back a:hover{color:#d86e18}\n.hlh-sls-c09 .stats{display:flex;flex-wrap:wrap;gap:.85rem;margin:1.8rem 0 2.2rem}\n.hlh-sls-c09 .stat{flex:1 1 145px;background:#1a3456;color:#fff;border-radius:8px;padding:1.1rem .9rem .9rem;text-align:center}\n.hlh-sls-c09 .stat-n{display:block;font-size:1.55rem;font-weight:700;color:#d86e18;line-height:1.1}\n.hlh-sls-c09 .stat-l{display:block;font-size:.78rem;margin-top:.3rem;opacity:.85;line-height:1.35}\n.hlh-sls-c09 .toc{background:#f0f4f8;border:1px solid #c9d8e8;border-left:5px solid #1a3456;border-radius:0 6px 6px 0;padding:1.2rem 1.5rem;margin:0 0 2.4rem}\n.hlh-sls-c09 .toc-h{font-size:.87rem;font-weight:700;color:#1a3456;text-transform:uppercase;letter-spacing:.07em;margin:0 0 .7rem}\n.hlh-sls-c09 .toc ol{margin:0;padding-left:1.2rem}.hlh-sls-c09 .toc li{font-size:.91rem;margin-bottom:.26rem}\n.hlh-sls-c09 .toc a{color:#1a3456;border-bottom:none;text-decoration:underline;text-decoration-color:rgba(26,52,86,.3)}.hlh-sls-c09 .toc a:hover{color:#d86e18}\n.hlh-sls-c09 .box{background:#f0f4f8;border:1px solid #c9d8e8;border-left:5px solid #1a3456;border-radius:0 6px 6px 0;padding:1.1rem 1.4rem;margin:1.4rem 0}\n.hlh-sls-c09 .box-a{background:#fff8f2;border-left-color:#d86e18}\n.hlh-sls-c09 .box h4{margin-top:0;color:#1a3456;font-size:.96rem}.hlh-sls-c09 .box p:last-child,.hlh-sls-c09 .box ul:last-child{margin-bottom:0}\n.hlh-sls-c09 .tw{overflow-x:auto;margin:1.4rem 0;border-radius:6px;border:1px solid #c9d8e8}\n.hlh-sls-c09 table{width:100%;border-collapse:collapse;font-size:.87rem;min-width:520px}\n.hlh-sls-c09 thead tr{background:#1a3456}.hlh-sls-c09 th{color:#fff;padding:.65rem .85rem;text-align:left;font-weight:600;font-size:.82rem;white-space:nowrap}\n.hlh-sls-c09 td{padding:.6rem .85rem;border-bottom:1px solid #e2eaf2;vertical-align:top}.hlh-sls-c09 tr:last-child td{border-bottom:none}.hlh-sls-c09 tbody tr:nth-child(even){background:#f7f9fb}.hlh-sls-c09 td strong{color:#1a3456}\n.hlh-sls-c09 .rel-g{display:grid;grid-template-columns:repeat(auto-fill,minmax(225px,1fr));gap:.8rem;margin:1.4rem 0 2rem}\n.hlh-sls-c09 .rel-c{background:#f7f9fb;border:1px solid #c9d8e8;border-top:3px solid #1a3456;border-radius:6px;padding:.9rem 1rem}\n.hlh-sls-c09 .rel-c a{display:block;font-weight:600;font-size:.9rem;color:#1a3456;border:none;margin-bottom:.22rem;line-height:1.4}.hlh-sls-c09 .rel-c a:hover{color:#d86e18}\n.hlh-sls-c09 .rel-c p{font-size:.81rem;color:#4a6278;margin:0;line-height:1.43}\n.hlh-sls-c09 .fi{border:1px solid #c9d8e8;border-radius:6px;margin-bottom:.52rem;overflow:hidden}\n.hlh-sls-c09 .fq{background:#f0f4f8;padding:.9rem 1.2rem;font-weight:600;font-size:.94rem;color:#1a3456;cursor:pointer;display:flex;justify-content:space-between;align-items:center;border:none;width:100%;text-align:left;transition:background .18s}.hlh-sls-c09 .fq:hover{background:#e4edf6}\n.hlh-sls-c09 .fi-icon{font-size:1.2rem;color:#d86e18;flex-shrink:0;margin-left:.9rem;transition:transform .22s;font-weight:400}.hlh-sls-c09 .fq.open .fi-icon{transform:rotate(45deg)}\n.hlh-sls-c09 .fa{display:none;padding:.88rem 1.2rem 1rem;font-size:.92rem;background:#fff;color:#2c3e50;line-height:1.78;border-top:1px solid #e2eaf2}.hlh-sls-c09 .fa.open{display:block}.hlh-sls-c09 .fa p:last-child{margin-bottom:0}\n.hlh-sls-c09 .cta{background:linear-gradient(135deg,#1a3456 0%,#24466e 100%);border-radius:10px;padding:2rem 2.3rem;margin:2.8rem 0 1rem;text-align:center}\n.hlh-sls-c09 .cta h3{color:#fff;font-size:1.28rem;margin:0 0 .6rem}.hlh-sls-c09 .cta p{color:rgba(255,255,255,.84);font-size:.94rem;margin-bottom:1.3rem}\n.hlh-sls-c09 .btn{display:inline-block;background:#d86e18;color:#fff!important;font-weight:700;font-size:1rem;padding:.73rem 2.1rem;border-radius:4px;text-decoration:none!important;border:none!important;transition:background .2s}.hlh-sls-c09 .btn:hover{background:#b85a10}\n@media(max-width:640px){.hlh-sls-c09 h1{font-size:1.5rem}.hlh-sls-c09 h2{font-size:1.2rem}.hlh-sls-c09 .cta{padding:1.5rem 1.2rem}}\n<\/style>\n<article class=\"hlh-sls-c09\">\n<div class=\"back\">&#8592; Part of: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-beads-sls-powder-removal-complete-guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Beads for SLS Powder Removal \u2014 Complete Guide<\/a><\/div>\n<h1>Color Consistency and Dye Preparation for SLS Parts After Ceramic Bead Blasting<\/h1>\n<p class=\"meta\">By Jiangsu Henglihong Technology Co., Ltd. &nbsp;|&nbsp; Last updated: July 2026<\/p>\n<p class=\"lead\">Colour consistency is one of the most commercially sensitive quality dimensions in SLS production. Parts that dye unevenly, show batch-to-batch colour variation, or carry visible patches under directional light generate customer complaints and rework costs that quickly dwarf the cost of the blasting operation itself. Ceramic bead blasting is the surface preparation step that eliminates these problems \u2014 by removing the heterogeneous semi-sintered skin and creating a uniform, controllable surface for dye uptake. This guide explains exactly how it works and how to dial in the protocol for your colour targets.<\/p>\n<div class=\"stats\">\n  <div class=\"stat\"><span class=\"stat-n\">Ra 6\u201310 \u00b5m<\/span><span class=\"stat-l\">Optimal surface roughness for standard PA12 SLS dyeing<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">2\u20134 h<\/span><span class=\"stat-l\">Maximum blast-to-dye-bath interval for dry-blasted PA12<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">\u0394E &lt; 2.0<\/span><span class=\"stat-l\">Typical batch colour consistency target for SLS production dyeing<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">3\u20134 \u00b5m<\/span><span class=\"stat-l\">Ra change achievable by bead size shift alone to adjust colour depth<\/span><\/div>\n<\/div>\n<nav class=\"toc\"><p class=\"toc-h\">Table of Contents<\/p>\n<ol>\n<li><a href=\"#c09-mechanism\">How PA12 and PA11 Absorb Dye: The Role of Surface Microstructure<\/a><\/li>\n<li><a href=\"#c09-unblasted\">Why Unblasted SLS Parts Dye Unevenly<\/a><\/li>\n<li><a href=\"#c09-blast-effect\">How Ceramic Bead Blasting Prepares the Surface for Dyeing<\/a><\/li>\n<li><a href=\"#c09-bead-colour\">Bead Size and Its Effect on Colour Depth<\/a><\/li>\n<li><a href=\"#c09-protocol\">Pre-Dye Blast Protocol by Colour Target<\/a><\/li>\n<li><a href=\"#c09-timing\">Timing: From Blast to Dye Bath<\/a><\/li>\n<li><a href=\"#c09-measure\">Colour Measurement and Batch Consistency<\/a><\/li>\n<li><a href=\"#c09-batch\">Batch-to-Batch Consistency Improvement<\/a><\/li>\n<li><a href=\"#c09-faq\">Questions fr\u00e9quemment pos\u00e9es<\/a><\/li>\n<\/ol><\/nav>\n\n<h2 id=\"c09-mechanism\">1. How PA12 and PA11 Absorb Dye: The Role of Surface Microstructure<\/h2>\n<p>PA12 and PA11 nylon SLS parts are typically dyed using acid dyes or reactive dyes formulated for polyamide. The dyeing mechanism is straightforward: dye molecules dissolved in a hot aqueous bath (typically 90\u201398\u00b0C) diffuse from solution into the surface of the nylon part. Once inside the nylon, they form ionic bonds with the amide groups (\u2013CO\u2013NH\u2013) in the polymer chain, becoming locked into the nylon structure and producing permanent colour.<\/p>\n<p>The depth and uniformity of this dye penetration is controlled by two factors: <strong>dye bath conditions<\/strong> (temperature, concentration, time, pH) and <strong>part surface microstructure<\/strong>. Dye bath conditions are straightforward to standardise. Surface microstructure, in contrast, is inherently variable on as-built SLS parts \u2014 which is the root cause of dyeing inconsistency in unprocessed SLS output.<\/p>\n<p>Dye molecules penetrate the nylon surface preferentially through the amorphous (non-crystalline) regions of the polymer, where chain mobility is higher and molecular packing is looser. The more amorphous the surface region, the faster and deeper the dye penetrates. Surface porosity \u2014 the density of micro-pores and surface voids \u2014 also accelerates dye uptake by increasing the surface area in contact with the dye solution per unit of projected area.<\/p>\n\n<h2 id=\"c09-unblasted\">2. Why Unblasted SLS Parts Dye Unevenly<\/h2>\n<p>As-built SLS parts have a heterogeneous surface at the microscale. The outermost layer \u2014 the semi-sintered skin \u2014 consists of partially fused nylon particles bonded to the part surface during the build. This skin has:<\/p>\n<ul>\n<li><strong>Higher amorphous content<\/strong> than the fully sintered bulk \u2014 partially sintered particles are less crystalline than fully fused nylon<\/li>\n<li><strong>Higher porosity<\/strong> \u2014 inter-particle voids in the semi-sintered zone create a sponge-like micro-texture<\/li>\n<li><strong>Heterogeneous distribution<\/strong> \u2014 the skin is thicker and more porous over areas that received more thermal exposure from adjacent laser scans; thinner and denser over areas at the outer boundary of the sintered zone<\/li>\n<\/ul>\n<p>When this heterogeneous surface enters the dye bath, dye penetrates rapidly and deeply into high-porosity zones (producing dark patches) and slowly and shallowly into dense zones (producing light patches). The result: a mottled, non-uniform colour that is especially visible on large flat faces, which simultaneously display areas sintered at different distances from laser scan lines.<\/p>\n<p>Build-to-build colour variation is the second consequence. Different builds produce slightly different thermal histories and slightly different semi-sintered skin properties \u2014 so even with identical dye bath conditions, different builds of the same part may emerge from the dye bath with measurably different colour (\u0394E 3\u20138 is typical for unblasted SLS parts dyed in the same bath).<\/p>\n\n<h2 id=\"c09-blast-effect\">3. How Ceramic Bead Blasting Prepares the Surface for Dyeing<\/h2>\n<p>Ceramic bead blasting removes the heterogeneous semi-sintered skin and exposes the uniform bulk sintered nylon beneath. The peening action of ceramic bead impact simultaneously:<\/p>\n<ul>\n<li>Breaks and dislodges the semi-sintered skin particles, exposing the more homogeneous sintered surface below<\/li>\n<li>Mechanically opens the surface microstructure \u2014 creating a consistent network of fine surface asperities and micro-scale deformation zones that are uniform across the entire blasted area<\/li>\n<li>Reduces and homogenises Ra across all build orientations, so horizontal and side faces present the same surface texture to the dye bath<\/li>\n<\/ul>\n<p>The result: a post-blast PA12 or PA11 surface that is compositionally and structurally uniform at the scale relevant to dye uptake. Dye molecules entering this surface find the same amorphous content, the same porosity, and the same surface texture everywhere \u2014 producing uniform colour uptake and dramatically reduced batch variation.<\/p>\n<p>Typical improvement in batch-to-batch \u0394E after implementing ceramic bead blasting before dyeing: from \u0394E 3\u20138 (unblasted) to \u0394E 0.5\u20132.0 (consistently blasted), achieved without any change to dye bath chemistry or process parameters.<\/p>\n\n<h2 id=\"c09-bead-colour\">4. Bead Size and Its Effect on Colour Depth<\/h2>\n<p>The surface Ra produced by the pre-dye blast controls the colour depth of the dyed part. This is a direct, reproducible, and process-controllable relationship:<\/p>\n<div class=\"tw\"><table><thead><tr><th>Bead Size (ZS)<\/th><th>Surface Ra After Blast<\/th><th>Dye Depth (Relative)<\/th><th>Colour Result<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>0.05\u20130.10 mm<\/td><td>Ra 3\u20136 \u00b5m<\/td><td>Shallow (lowest)<\/td><td>Light, pastel, high chroma at reduced saturation<\/td><\/tr>\n<tr><td>0.10\u20130.15 mm<\/td><td>Ra 4\u20138 \u00b5m<\/td><td>Moderate-light<\/td><td>Medium-light; ideal for bright primaries and light tones<\/td><\/tr>\n<tr><td>0.15\u20130.20 mm<\/td><td>Ra 6\u201310 \u00b5m<\/td><td>Moderate-deep<\/td><td>Standard production colour depth; recommended starting point<\/td><\/tr>\n<tr><td>0.20\u20130.30 mm<\/td><td>Ra 8\u201313 \u00b5m<\/td><td>Deep<\/td><td>Maximum saturation; ideal for black, navy, dark grey<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>The mechanism: higher Ra means more surface area per projected unit area, more surface micro-porosity per unit, and deeper surface asperities for dye molecules to enter. At Ra 6\u201310 \u00b5m the surface provides a balance of dye depth and colour uniformity that works across most standard colour targets. Moving to coarser beads and higher Ra deepens colour further but also slightly increases colour variation within a batch (because the more textured surface has more local Ra variability).<\/p>\n<p><strong>Practical application:<\/strong> if your standard black protocol consistently produces a finished part that is \u0394E 3\u20135 lighter than your colour standard, switch from 0.10\u20130.15 mm to 0.18\u20130.25 mm beads before the dye bath. The colour will deepen measurably without any change to dye bath concentration or temperature \u2014 a cleaner, less costly adjustment than increasing dye loading.<\/p>\n\n<h2 id=\"c09-protocol\">5. Pre-Dye Blast Protocol by Colour Target<\/h2>\n<div class=\"tw\"><table><thead><tr><th>Colour Category<\/th><th>Examples<\/th><th>Recommended Bead Size<\/th><th>Pressure<\/th><th>Target Ra<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Very dark \/ maximum depth<\/strong><\/td><td>Black, graphite, dark navy<\/td><td>ZS 0.18\u20130.28 mm<\/td><td>60\u201370 PSI<\/td><td>Ra 8\u201313 \u00b5m<\/td><\/tr>\n<tr><td><strong>Standard dark colours<\/strong><\/td><td>Navy, dark red, dark green<\/td><td>ZS 0.15\u20130.22 mm<\/td><td>57\u201367 PSI<\/td><td>Ra 7\u201311 \u00b5m<\/td><\/tr>\n<tr><td><strong>Standard mid-tone colours<\/strong><\/td><td>Medium blue, standard red, forest green<\/td><td>ZS 0.12\u20130.18 mm<\/td><td>53\u201363 PSI<\/td><td>Ra 5\u20139 \u00b5m<\/td><\/tr>\n<tr><td><strong>Light \/ pastel colours<\/strong><\/td><td>Sky blue, light grey, pale yellow<\/td><td>ZS 0.08\u20130.14 mm<\/td><td>47\u201357 PSI<\/td><td>Ra 4\u20137 \u00b5m<\/td><\/tr>\n<tr><td><strong>Colour calibration (first article)<\/strong><\/td><td>Any new colour standard<\/td><td>Blast coupon at 2 sizes; measure \u0394E against standard<\/td><td>As above<\/td><td>Select by \u0394E result<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>These are starting protocols \u2014 each operation will need to validate against their own dye formulation, bath temperature, and part geometry. The table provides the pre-dye blast parameter search space; first-article dye trials with colour measurement identify the optimum point within that space for your specific colour standards.<\/p>\n\n<h2 id=\"c09-timing\">6. Timing: From Blast to Dye Bath<\/h2>\n<p>The interval between ceramic bead blasting and immersion in the dye bath affects colour uptake because the blasted surface can be contaminated or its chemistry altered between the two operations.<\/p>\n<div class=\"box box-a\">\n<h4>Blast-to-dye timing rules<\/h4>\n<ul>\n<li><strong>Ideal:<\/strong> transfer to dye bath within 1\u20132 hours of blasting, while the surface is freshly opened and clean<\/li>\n<li><strong>Acceptable:<\/strong> up to 4 hours for dry-blasted PA12 in a clean, low-humidity environment<\/li>\n<li><strong>Maximum:<\/strong> 24 hours if stored in a sealed clean bag in a low-humidity environment; risk of mild colour variation from ambient contamination increases over this interval<\/li>\n<li><strong>Never:<\/strong> dye parts that have been handled with bare hands after blasting (skin oils contaminate the surface and produce lighter spots or pinholes in the colour)<\/li>\n<li><strong>Wet-blasted parts:<\/strong> dry at 60\u201370\u00b0C for 2\u20134 hours first; transfer to dye bath within 1 hour of removing from oven<\/li>\n<\/ul>\n<\/div>\n<p>Between blasting and dyeing, avoid contact with cutting oils, mould release agents, packaging plastics that outgas plasticisers, or humid environments. Any surface contamination that interferes with the dye bath&#8217;s wetting of the nylon surface will produce pinholes or local colour voids in the finished part.<\/p>\n\n<h2 id=\"c09-measure\">7. Colour Measurement and Batch Consistency<\/h2>\n<p>Colour measurement on dyed SLS parts uses a spectrophotometer to quantify colour as CIE L*a*b* coordinates. The key metric for batch consistency is <strong>\u0394E<\/strong> (also written \u0394E00 for the CIEDE2000 formula) \u2014 the total colour difference between a measured part and the approved colour standard.<\/p>\n<ul>\n<li><strong>\u0394E &lt; 1.0:<\/strong> imperceptible colour difference \u2014 excellent for any application<\/li>\n<li><strong>\u0394E 1.0\u20132.0:<\/strong> very slight difference perceptible only under ideal viewing conditions \u2014 typically acceptable for production SLS parts<\/li>\n<li><strong>\u0394E 2.0\u20133.5:<\/strong> visible difference under side-by-side comparison \u2014 may or may not be acceptable depending on application<\/li>\n<li><strong>\u0394E &gt; 3.5:<\/strong> clearly visible to most observers \u2014 typically not acceptable for commercial appearance parts<\/li>\n<\/ul>\n<p>For production QC, measure at least 3 parts per batch at a standardised surface location and orientation (horizontal face, same position relative to the build direction). Measure against a colour standard that was established from a part that was blasted with the same protocol that will be used in production.<\/p>\n<p><strong>Important:<\/strong> establish the colour standard from a part that was blasted with the same protocol, not from an unblasted reference \u2014 otherwise the standard includes the colour shift produced by blasting, and any production part blasted at a different Ra will show a colour deviation against that standard.<\/p>\n\n<h2 id=\"c09-batch\">8. Batch-to-Batch Colour Consistency Improvement<\/h2>\n<p>The most commercially visible improvement from introducing ceramic bead blasting into an SLS dyeing workflow is the reduction in batch-to-batch colour variation. SLS builds inherently vary slightly in their thermal history \u2014 slight temperature fluctuations in the build chamber, powder reuse ratios, and part packing density all affect the crystallinity and surface structure of the semi-sintered skin. Without blasting, these build-to-build variations translate directly into colour variation.<\/p>\n<p>With a standardised pre-dye ceramic bead blast protocol, the starting surface condition for each batch is normalised: the semi-sintered skin (which varies between builds) is removed, and a consistent Ra surface (which is controlled by the blast protocol, not the build parameters) is presented to the dye bath. The result is that batch-to-batch \u0394E, which commonly runs 3\u20138 on unblasted SLS production, typically falls to 0.5\u20132.0 after a standardised blast protocol is established and maintained.<\/p>\n<p>For SLS operations where colour consistency is a customer specification \u2014 particularly in consumer products, medical devices, and branded industrial components \u2014 this improvement in batch consistency is often the primary business case for ceramic bead blasting, independent of the surface finish Ra benefit.<\/p>\n\n<div class=\"fi\" style=\"border:1px solid #c9d8e8;border-radius:6px;padding:0;margin:1.5rem 0 2rem;overflow:hidden\">\n<div style=\"background:#f0f4f8;padding:1rem 1.25rem;border-top:3px solid #d86e18\">\n<span style=\"display:block;font-size:.74rem;font-weight:700;color:#d86e18;text-transform:uppercase;letter-spacing:.06em;margin-bottom:.18rem\">Related Reference<\/span>\n<a href=\"https:\/\/hlh-js.com\/resource\/blog\/surface-finish-and-ra-values-after-ceramic-bead-blasting-sls-3d-printed-parts\/\" target=\"_blank\" rel=\"noopener noreferrer\" style=\"font-size:.94rem;font-weight:600;color:#1a3456;border:none;display:block;margin-bottom:.18rem\">Surface Finish Ra Values After Ceramic Bead Blasting SLS 3D Printed Parts<\/a>\n<p style=\"font-size:.85rem;color:#4a6278;margin:0;line-height:1.5\">Ra data by bead grade, size, and process conditions \u2014 the surface finish foundation for dye preparation.<\/p>\n<\/div><\/div>\n\n<h2 id=\"c09-faq\">Questions fr\u00e9quemment pos\u00e9es<\/h2>\n<div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">Why do unblasted SLS parts often look patchy or uneven after dyeing? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>As-built SLS parts have a heterogeneous surface: the semi-sintered skin has higher porosity and amorphous content than the fully sintered bulk material. Dye penetrates faster and deeper into high-porosity semi-sintered zones, producing darker patches, while denser sintered zones absorb dye more slowly and appear lighter. The result is a mottled, non-uniform colour clearly visible under directional light. Ceramic bead blasting removes this heterogeneous semi-sintered layer and exposes a uniform, dense sintered surface that absorbs dye evenly \u2014 eliminating colour patchiness.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">What ceramic bead size should I use for pre-dyeing blast of PA12 SLS parts? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>For standard and dark colours (black, navy, dark grey): ZS 0.15\u20130.22 mm to achieve Ra 7\u201311 \u00b5m \u2014 gives deep, saturated colour. For medium colours (standard red, blue, green): ZS 0.12\u20130.18 mm for Ra 5\u20139 \u00b5m \u2014 balanced depth and uniformity. For light or pastel shades: ZS 0.08\u20130.14 mm for Ra 4\u20137 \u00b5m \u2014 limits dye uptake depth for lighter saturation. Validate your selection by blasting reference coupons at two sizes and measuring colour with a spectrophotometer against your colour standard before committing to a production pre-dye protocol.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">How long after ceramic bead blasting should I put SLS parts into the dye bath? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Transfer dry-blasted PA12 SLS parts to the dye bath within 2 to 4 hours of blasting. Parts exposed to ambient air for longer may accumulate surface dust or moisture that interferes with even dye uptake. If dyeing cannot begin within 4 hours, store blasted parts in a sealed clean bag. Never handle blasted parts with bare hands before dyeing \u2014 skin oils contaminate the blasted surface and produce pinholes or local colour voids in the finished part. For wet-blasted parts, dry at 60\u201370\u00b0C for 2\u20134 hours before dyeing.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">Can I adjust dye colour depth by changing the ceramic bead blast protocol? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Yes \u2014 bead size is a direct control variable for colour depth. Finer beads produce lower Ra (smoother surface) which limits dye penetration depth, giving lighter, more pastel results. Coarser beads produce higher Ra (more texture) which increases dye uptake area and depth, giving deeper, more saturated colour. If your standard black dye bath is producing lighter-than-target output, switching from 0.10\u20130.15 mm to 0.18\u20130.25 mm beads will deepen the colour without changing dye chemistry. This bead-size approach to colour control works independently of dye bath concentration and temperature, providing a cost-effective tuning lever for existing dye operations.<\/p><\/div><\/div>\n<\/div>\n\n<h2>Related Articles in This Series<\/h2>\n<p>Return to the <a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-beads-sls-powder-removal-complete-guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Beads for SLS Powder Removal \u2014 Complete Guide<\/a> for the full overview.<\/p>\n<div class=\"rel-g\">\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-blasting-pa12-nylon-sls-parts-depowdering-and-surface-prep\/\" target=\"_blank\" rel=\"noopener noreferrer\">PA12 SLS Depowdering Protocol<\/a><p>PA12-specific blast protocol including pre-dyeing surface prep and Ra targets.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-depowdering-pa11-nylon-sls-parts-bio-based-material-processing\/\" target=\"_blank\" rel=\"noopener noreferrer\">PA11 SLS Depowdering Protocol<\/a><p>PA11 dyeing differences from PA12 \u2014 dwell time adjustment and moisture management.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-size-selection-for-sls-powder-removal-matching-mesh-to-part-geometry\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Bead Size Selection Guide<\/a><p>Complete size selection matrix \u2014 how to choose bead size for both cleaning and colour targets.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/surface-finish-and-ra-values-after-ceramic-bead-blasting-sls-3d-printed-parts\/\" target=\"_blank\" rel=\"noopener noreferrer\">Surface Finish Ra Values After Blasting<\/a><p>Ra data by bead grade, size, and pressure \u2014 the technical basis for colour depth control.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/wet-vs-dry-ceramic-bead-blasting-for-sls-nylon-powder-removal-process-comparison\/\" target=\"_blank\" rel=\"noopener noreferrer\">Wet vs. Dry Ceramic Bead Blasting<\/a><p>How the choice of wet or dry blasting affects surface condition and colour uniformity before dyeing.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/blast-pressure-and-cycle-time-for-ceramic-bead-sls-depowdering-optimization-guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Blast Pressure and Cycle Time Optimization<\/a><p>Pressure and cycle time parameters that work in combination with bead size to control Ra.<\/p><\/div>\n<\/div>\n<div class=\"cta\"><h3>Specify Ceramic Beads for Consistent SLS Dyeing Results<\/h3>\n<p>Jiangsu Henglihong Technology Co., Ltd. supplies ZS ceramic blasting beads in size ranges from 0.05 mm to 0.35 mm specifically suited for pre-dyeing surface preparation of PA12 and PA11 SLS parts. Tell us your colour target and current dyeing protocol \u2014 we will recommend the right bead size range and provide samples for first-article dye validation.<\/p>\n<a href=\"https:\/\/hlh-js.com\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"btn\">Request Samples &amp; Colour Prep Guidance<\/a><\/div>\n<\/article>\n<script>(function(){var b=document.querySelectorAll('.hlh-sls-c09 .fq');b.forEach(function(btn){btn.addEventListener('click',function(){var a=this.nextElementSibling,o=a.classList.contains('open');document.querySelectorAll('.hlh-sls-c09 .fa').forEach(function(x){x.classList.remove('open')});document.querySelectorAll('.hlh-sls-c09 .fq').forEach(function(x){x.classList.remove('open');x.setAttribute('aria-expanded','false')});if(!o){a.classList.add('open');btn.classList.add('open');btn.setAttribute('aria-expanded','true')}})})})();<\/script>","protected":false},"excerpt":{"rendered":"<p>&#8592; Part of: Ceramic Beads for SLS Powder Removal \u2014  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":13874,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,175,138],"tags":[],"class_list":["post-13872","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-industry","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts\/13872","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/comments?post=13872"}],"version-history":[{"count":2,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts\/13872\/revisions"}],"predecessor-version":[{"id":13875,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts\/13872\/revisions\/13875"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/media\/13874"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/media?parent=13872"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/categories?post=13872"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/tags?post=13872"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}