{"id":15026,"date":"2026-10-09T08:31:46","date_gmt":"2026-10-09T08:31:46","guid":{"rendered":"https:\/\/weldomachining.com\/?page_id=15026"},"modified":"2026-10-10T01:22:55","modified_gmt":"2026-10-10T01:22:55","slug":"black-oxide-coating","status":"publish","type":"page","link":"https:\/\/weldomachining.com\/ko\/black-oxide-coating\/","title":{"rendered":"\ud751\uc0c9 \uc0b0\ud654 \ud53c\ub9c9"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"15026\" class=\"elementor elementor-15026\" data-elementor-post-type=\"page\">\n\t\t\t\t<div class=\"elementor-element elementor-element-9a32685 e-con-full e-flex e-con e-parent\" data-id=\"9a32685\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-19bdcc7 elementor-widget elementor-widget-html\" data-id=\"19bdcc7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<style>\n:root {\n  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margin-bottom:8px; }\n}\n\n@media (max-width:420px) {\n  tbody td {\n    grid-template-columns:1fr;\n    gap:4px;\n  }\n}\n\n@media (prefers-reduced-motion:reduce) {\n  html { scroll-behavior:auto; }\n  .btn { transition:none; }\n}\n<\/style>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-fb14ce1 elementor-widget elementor-widget-html\" data-id=\"fb14ce1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"hero\" id=\"top\">\n  <div class=\"wrap hero-grid\">\n    <div class=\"hero-media\">\n      <img fetchpriority=\"high\" decoding=\"async\"\n        src=\"https:\/\/weldomachining.com\/wp-content\/uploads\/2026\/10\/black-oxide-cnc-parts.webp\"\n        alt=\"Black oxide coated CNC-machined metal gears shafts and fasteners\"\n        width=\"1400\"\n        height=\"933\"\n        fetchpriority=\"high\">\n    <\/div>\n\n    <div class=\"hero-copy\">\n      <p class=\"eyebrow\">Precision surface finishing<\/p>\n      <h1>Black Oxide Coating <\/h1>\n\n      <p class=\"lead\">\n        Black oxide gives compatible ferrous-metal parts a low-glare\n        finish with minimal effect on threads, bores and close fits.\n      <\/p>\n\n      <ul class=\"chips\" aria-label=\"Key capabilities\">\n        <li>Minimal dimensional buildup<\/li>\n        <li>Oil, wax or dry seal<\/li>\n        <li>Hot and stainless processes<\/li>\n        <li>Post-finish inspection<\/li>\n      <\/ul>\n\n      <a class=\"btn\" href=\"https:\/\/weldomachining.com\/file-upload\/\">\n        Upload Drawing for Quote\n      <\/a>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5cd663a elementor-widget elementor-widget-html\" data-id=\"5cd663a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section\" id=\"process-selection\">\n  <div class=\"wrap\">\n    <div class=\"section-head\">\n      <p class=\"eyebrow\">Process selection<\/p>\n      <h2>Which Black Oxide Process Is Right?<\/h2>\n      <p class=\"lead\">\n        Select the process according to material, heat-treatment\n        condition and coating specification.\n      <\/p>\n    <\/div>\n\n    <div class=\"grid four\">\n      <article class=\"card\">\n        <h3>Hot Black Oxide<\/h3>\n        <p>\n          Processed at about 135\u2013150\u00b0C for steel, tool steel\n          and compatible cast iron.\n        <\/p>\n      <\/article>\n\n      <article class=\"card\">\n        <h3>Mid-Temperature Black Oxide<\/h3>\n        <p>\n          Processed at about 90\u2013120\u00b0C for approved industrial applications.\n        <\/p>\n      <\/article>\n\n      <article class=\"card\">\n        <h3>Stainless Steel Black Oxide<\/h3>\n        <p>\n          Uses dedicated chemistry matched to the stainless grade\n          and specification.\n        <\/p>\n      <\/article>\n\n      <article class=\"card\">\n        <h3>Room-Temperature Blackening<\/h3>\n        <p>\n          Restores black color during approved local touch-up;\n          specification-controlled coating uses the required hot\n          or dedicated process.\n        <\/p>\n      <\/article>\n    <\/div>\n\n    <div class=\"spec-strip\" aria-label=\"Black oxide process parameters\">\n      <div class=\"spec\">\n        <b>135\u2013150\u00b0C<\/b>\n        <span>Typical hot-process range<\/span>\n      <\/div>\n\n      <div class=\"spec\">\n        <b>Minimal buildup<\/b>\n        <span>No appreciable dimensional change<\/span>\n      <\/div>\n\n      <div class=\"spec\">\n        <b>Fe\u2083O\u2084<\/b>\n        <span>Primary oxide on ferrous steel<\/span>\n      <\/div>\n\n      <div class=\"spec\">\n        <b>Oil \/ Wax \/ Dry<\/b>\n        <span>Post-treatment choices<\/span>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7ac18be elementor-widget elementor-widget-html\" data-id=\"7ac18be\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section alt\" id=\"workflow\">\n  <div class=\"wrap\">\n    <div class=\"section-head\">\n      <p class=\"eyebrow\">Controlled workflow<\/p>\n      <h2>How Is Black Oxide Applied?<\/h2>\n      <p class=\"lead\">\n        Five controlled stages determine coating consistency and protection.\n      <\/p>\n    <\/div>\n\n    <div class=\"steps\">\n      <div class=\"step\">\n        <b>Review<\/b>\n        <span>Verify material, hardness, drawing and masking.<\/span>\n      <\/div>\n\n      <div class=\"step\">\n        <b>Clean &amp; Activate<\/b>\n        <span>Remove oil, rust and heat-treatment scale.<\/span>\n      <\/div>\n\n      <div class=\"step\">\n        <b>Blacken<\/b>\n        <span>Control bath chemistry, temperature and time.<\/span>\n      <\/div>\n\n      <div class=\"step\">\n        <b>Rinse &amp; Seal<\/b>\n        <span>Rinse thoroughly and apply oil, wax or dry film.<\/span>\n      <\/div>\n\n      <div class=\"step\">\n        <b>Inspect<\/b>\n        <span>Check appearance, dimensions and packaging.<\/span>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-fef2486 elementor-widget elementor-widget-html\" data-id=\"fef2486\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<style>\n  .materials-section {\n    padding: 76px 0;\n    background: #ffffff;\n  }\n\n  .materials-wrap {\n    width: min(1160px, calc(100% - 40px));\n    margin-inline: auto;\n  }\n\n  .materials-head {\n    max-width: 790px;\n    margin-bottom: 32px;\n  }\n\n  .materials-eyebrow {\n    margin: 0 0 11px;\n    color: #30328e;\n    font-size: 13px;\n    line-height: 1.3;\n    font-weight: 700;\n    letter-spacing: 0.11em;\n    text-transform: uppercase;\n  }\n\n  .materials-title {\n    margin: 0 0 16px;\n    color: #22266c;\n    font-size: clamp(27px, 3vw, 36px);\n    line-height: 1.16;\n    letter-spacing: -0.025em;\n  }\n\n  .materials-lead {\n    max-width: 780px;\n    margin: 0;\n    color: #4f6671;\n    font-size: 17px;\n    line-height: 1.68;\n  }\n\n  .materials-layout {\n    display: grid;\n    grid-template-columns: minmax(0, 1.28fr) minmax(300px, 0.72fr);\n    gap: 28px;\n    align-items: stretch;\n  }\n\n  .materials-grid {\n    display: grid;\n    grid-template-columns: repeat(2, minmax(0, 1fr));\n    gap: 20px;\n  }\n\n  .material-card {\n    height: 100%;\n    padding: 24px;\n    border: 1px solid #dce8ed;\n    border-radius: 18px;\n    background: #ffffff;\n    box-shadow: 0 8px 24px rgba(37, 59, 70, 0.04);\n  }\n\n  .material-card h3 {\n    margin: 0 0 9px;\n    color: #22266c;\n    font-size: 18px;\n    line-height: 1.3;\n  }\n\n  .material-card p {\n    margin: 0;\n    color: #536a75;\n    font-size: 15px;\n    line-height: 1.6;\n  }\n\n  .materials-photo {\n    display: flex;\n    flex-direction: column;\n    justify-content: center;\n    margin: 0;\n    padding: 14px;\n    border: 1px solid #dce8ed;\n    border-radius: 20px;\n    background: #ffffff;\n    box-shadow: 0 18px 50px rgba(37, 59, 70, 0.1);\n  }\n\n  .materials-photo img {\n    display: block;\n    width: 100%;\n    height: auto;\n    max-height: 520px;\n    object-fit: contain;\n    border-radius: 13px;\n  }\n\n  .materials-photo figcaption {\n    padding: 12px 4px 2px;\n    color: #607681;\n    font-size: 13px;\n    line-height: 1.45;\n    text-align: center;\n  }\n\n  .materials-note {\n    margin: 20px 0 0;\n    padding: 16px 18px;\n    border-left: 4px solid #51acc8;\n    border-radius: 0 10px 10px 0;\n    background: #eef7fa;\n    color: #4e6570;\n    font-size: 15px;\n    line-height: 1.6;\n  }\n\n  @media (max-width: 980px) {\n    .materials-section {\n      padding: 64px 0;\n    }\n\n    .materials-layout {\n      grid-template-columns: 1fr;\n    }\n\n    .materials-photo {\n      width: 100%;\n      max-width: 620px;\n      margin-inline: auto;\n    }\n  }\n\n  @media (max-width: 720px) {\n    .materials-section {\n      padding: 52px 0;\n    }\n\n    .materials-wrap {\n      width: min(100% - 28px, 1160px);\n    }\n\n    .materials-title {\n      font-size: 26px;\n    }\n\n    .materials-lead {\n      font-size: 16px;\n    }\n\n    .materials-grid {\n      grid-template-columns: 1fr;\n    }\n\n    .materials-photo {\n      padding: 10px;\n      border-radius: 16px;\n    }\n\n    .materials-photo img {\n      max-height: none;\n    }\n  }\n<\/style>\n\n<section class=\"materials-section\" id=\"materials\">\n  <div class=\"materials-wrap\">\n\n    <div class=\"materials-head\">\n      <p class=\"materials-eyebrow\">Suitable materials<\/p>\n\n      <h2 class=\"materials-title\">\n        Black Oxide Compatible Materials\n      <\/h2>\n\n      <p class=\"materials-lead\">\n        Material grade and surface condition determine the finish and sealing route.\n      <\/p>\n    <\/div>\n\n    <div class=\"materials-layout\">\n\n      <div class=\"materials-grid\">\n        <article class=\"material-card\">\n          <h3>Carbon Steel<\/h3>\n          <p>\n            Creates a uniform sealed finish for pins, sleeves, brackets and screws.\n          <\/p>\n        <\/article>\n\n        <article class=\"material-card\">\n          <h3>Alloy Steel<\/h3>\n          <p>\n            Preserves close fits on gears, shafts, bushings and high-strength fasteners.\n          <\/p>\n        <\/article>\n\n        <article class=\"material-card\">\n          <h3>Tool Steel<\/h3>\n          <p>\n            Adds low-glare rust protection to punches, dies and tool holders.\n          <\/p>\n        <\/article>\n\n        <article class=\"material-card\">\n          <h3>Cast Iron<\/h3>\n          <p>\n            Supports appearance and light protection on gears, pulleys and housings.\n          <\/p>\n        <\/article>\n\n        <article class=\"material-card\">\n          <h3>Stainless Steel<\/h3>\n          <p>\n            Dedicated chemistry darkens instrument parts, optical hardware and fasteners.\n          <\/p>\n        <\/article>\n\n        <article class=\"material-card\">\n          <h3>Powder-Metal Parts<\/h3>\n          <p>\n            Oil sealing supports sintered gears, sprockets and bushings after thorough rinsing.\n          <\/p>\n        <\/article>\n      <\/div>\n\n      <figure class=\"materials-photo\">\n        <img loading=\"lazy\" decoding=\"async\"\n          src=\"https:\/\/weldomachining.com\/wp-content\/uploads\/2026\/10\/Black-oxide-parts-in-multiple-ferrous-materials.webp\"\n          alt=\"Black oxide coated metal parts\"\n          width=\"700\"\n          height=\"700\"\n          loading=\"lazy\"\n        >\n        <figcaption>\n          Black oxide parts in multiple ferrous materials.\n        <\/figcaption>\n      <\/figure>\n\n    <\/div>\n\n    <p class=\"materials-note\">\n      Aluminum normally uses black anodizing. Copper and brass require dedicated chemical blackening processes and should be specified separately from ferrous black oxide.\n    <\/p>\n\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f6bfc25 elementor-widget elementor-widget-html\" data-id=\"f6bfc25\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section alt\" id=\"standards\">\n  <div class=\"wrap\">\n    <div class=\"section-head\">\n      <p class=\"eyebrow\">Drawing requirements<\/p>\n      <h2>Black Oxide Drawing Requirements<\/h2>\n      <p class=\"lead\">\n        State the substrate, standard revision, process class, sealer,\n        treatment area, masking area and inspection method.\n      <\/p>\n    <\/div>\n\n    <div class=\"table-shell\">\n      <table>\n        <thead>\n          <tr>\n            <th>Standard<\/th>\n            <th>Main application<\/th>\n            <th>What to specify<\/th>\n          <\/tr>\n        <\/thead>\n\n        <tbody>\n          <tr>\n            <td data-label=\"Standard\">MIL-DTL-13924F<\/td>\n            <td data-label=\"Main application\">\n              Inorganic black conversion coatings for ferrous metals\n            <\/td>\n            <td data-label=\"What to specify\">\n              Class 1, 2, 3 or 4, preservative treatment and inspection\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Standard\">SAE AMS2485M<\/td>\n            <td data-label=\"Main application\">\n              Engineering and aerospace black oxide coatings\n            <\/td>\n            <td data-label=\"What to specify\">\n              Material condition, pre\/post-treatment and acceptance\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Standard\">ISO 11408:1999<\/td>\n            <td data-label=\"Main application\">\n              Cast iron, carbon steel, low-alloy and stainless steel\n            <\/td>\n            <td data-label=\"What to specify\">\n              Substrate, supplementary protection and testing\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Standard\">DIN 50938:2025-06<\/td>\n            <td data-label=\"Main application\">\n              Immersion black oxide on ferrous components\n            <\/td>\n            <td data-label=\"What to specify\">\n              Substrate and inspection; excludes fasteners\n              and semi-finished products\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Standard\">SAE AMS2489B<\/td>\n            <td data-label=\"Main application\">\n              Ambient-temperature color restoration after\n              black oxide removal\n            <\/td>\n            <td data-label=\"What to specify\">\n              Touch-up area; visual color restoration only\n            <\/td>\n          <\/tr>\n        <\/tbody>\n      <\/table>\n    <\/div>\n\n    <p class=\"note\">\n      For steel hardened to 39 HRC or above, MIL-DTL-13924F requires\n      the specified pre-process stress relief and post-coating\n      hydrogen-embrittlement relief before the supplementary preservative,\n      unless an approved exception applies.\n    <\/p>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-160baf3 elementor-widget elementor-widget-html\" data-id=\"160baf3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section\" id=\"sealers\">\n  <div class=\"wrap media-split\">\n    <div class=\"media-card\">\n      <img loading=\"lazy\" decoding=\"async\"\n        src=\"https:\/\/weldomachining.com\/wp-content\/uploads\/2026\/10\/black-oxide-masking.webp\"\n        alt=\"Technician preparing masked steel parts for black oxide coating\"\n        width=\"1400\"\n        height=\"933\"\n        loading=\"lazy\">\n    <\/div>\n\n    <div>\n      <p class=\"eyebrow\">Appearance and sealing<\/p>\n      <h2>Black Oxide Sealer Options<\/h2>\n      <p>\n        The original texture and selected sealer determine the final\n        shade, gloss and rust protection.\n      <\/p>\n\n      <div class=\"grid two\">\n        <article class=\"card\">\n          <h3>Oil Seal<\/h3>\n          <p>\n            Improves rust protection for gears, shafts,\n            tools and lubricated parts.\n          <\/p>\n        <\/article>\n\n        <article class=\"card\">\n          <h3>Wax Seal<\/h3>\n          <p>\n            Provides a drier handling surface for fixtures\n            and indoor hardware.\n          <\/p>\n        <\/article>\n\n        <article class=\"card\">\n          <h3>Dry-to-Touch Seal<\/h3>\n          <p>\n            Supports clean handling when oil transfer must be limited.\n          <\/p>\n        <\/article>\n\n        <article class=\"card\">\n          <h3>Unsealed<\/h3>\n          <p>\n            Selected when another coating or bonding process\n            follows blackening.\n          <\/p>\n        <\/article>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-fafeb91 elementor-widget elementor-widget-html\" data-id=\"fafeb91\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section alt\" id=\"benefits\">\n  <div class=\"wrap\">\n    <div class=\"section-head\">\n      <p class=\"eyebrow\">Performance<\/p>\n      <h2>Benefits of Black Oxide<\/h2>\n      <p class=\"lead\">\n        Black oxide provides a dark, low-build finish and light-duty\n        protection while the substrate controls strength and hardness.\n      <\/p>\n    <\/div>\n\n    <div class=\"benefits\">\n      <article class=\"benefit\">\n        <span class=\"num\">01<\/span>\n        <h3>Minimal dimensional change<\/h3>\n        <p>\n          The conversion finish causes no appreciable buildup on\n          threads, bores, shafts and close fits.\n        <\/p>\n      <\/article>\n\n      <article class=\"benefit\">\n        <span class=\"num\">02<\/span>\n        <h3>Low-reflective appearance<\/h3>\n        <p>\n          The dark finish reduces glare on instruments,\n          tooling and internal components.\n        <\/p>\n      <\/article>\n\n      <article class=\"benefit\">\n        <span class=\"num\">03<\/span>\n        <h3>Preserved texture<\/h3>\n        <p>\n          Polished, ground and blasted surfaces retain\n          their original texture.\n        <\/p>\n      <\/article>\n\n      <article class=\"benefit\">\n        <span class=\"num\">04<\/span>\n        <h3>Light corrosion protection<\/h3>\n        <p>\n          Sealing supports storage, assembly and controlled indoor use.\n        <\/p>\n      <\/article>\n\n      <article class=\"benefit\">\n        <span class=\"num\">05<\/span>\n        <h3>Lubricant retention<\/h3>\n        <p>\n          An oiled surface retains lubricant on sliding\n          and threaded contacts.\n        <\/p>\n      <\/article>\n\n      <article class=\"benefit\">\n        <span class=\"num\">06<\/span>\n        <h3>Base properties preserved<\/h3>\n        <p>\n          A correctly specified process preserves the established\n          hardness and strength of the substrate.\n        <\/p>\n      <\/article>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5e6bf8b elementor-widget elementor-widget-html\" data-id=\"5e6bf8b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section\" id=\"comparison\">\n  <div class=\"wrap\">\n    <div class=\"section-head\">\n      <p class=\"eyebrow\">Finish comparison<\/p>\n      <h2>Black Oxide vs. Black Zinc<\/h2>\n      <p class=\"lead\">\n        Choose black oxide for minimal buildup and low glare.\n        Choose black zinc for stronger sacrificial corrosion protection.\n      <\/p>\n    <\/div>\n\n    <div class=\"table-shell\">\n      <table>\n        <thead>\n          <tr>\n            <th>Key difference<\/th>\n            <th>Black oxide<\/th>\n            <th>Black zinc plating<\/th>\n          <\/tr>\n        <\/thead>\n\n        <tbody>\n          <tr>\n            <td data-label=\"Key difference\">Formation<\/td>\n            <td data-label=\"Black oxide\">\n              Chemical conversion of the ferrous surface\n            <\/td>\n            <td data-label=\"Black zinc plating\">\n              Electrodeposited zinc followed by black passivation\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Key difference\">Dimensional buildup<\/td>\n            <td data-label=\"Black oxide\">\n              No appreciable dimensional change\n            <\/td>\n            <td data-label=\"Black zinc plating\">\n              Several to tens of micrometers, as specified\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Key difference\">Corrosion protection<\/td>\n            <td data-label=\"Black oxide\">\n              Light duty; depends on the sealer\n            <\/td>\n            <td data-label=\"Black zinc plating\">\n              Higher sacrificial protection\n            <\/td>\n          <\/tr>\n\n          <tr>\n            <td data-label=\"Key difference\">Typical parts<\/td>\n            <td data-label=\"Black oxide\">\n              Tools, gears, shafts, fixtures and precision fasteners\n            <\/td>\n            <td data-label=\"Black zinc plating\">\n              Automotive hardware, brackets and exposed fasteners\n            <\/td>\n          <\/tr>\n        <\/tbody>\n      <\/table>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a99d6c4 elementor-widget elementor-widget-html\" data-id=\"a99d6c4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section alt\" id=\"masking-dimensions\">\n  <div class=\"wrap\">\n    <div class=\"callout\">\n      <div>\n        <p class=\"eyebrow\">Masking and fit<\/p>\n        <h2>What Should Be Masked?<\/h2>\n        <p>\n          Masking protects surfaces where oxide or sealer would\n          affect electrical contact, bonding, welding, sealing\n          or the next manufacturing operation.\n        <\/p>\n      <\/div>\n\n      <ul class=\"callout-list\">\n        <li>Bonding and welding surfaces<\/li>\n        <li>Defined electrical contacts<\/li>\n        <li>Oil-sensitive sealing surfaces<\/li>\n        <li>Vacuum and clean-service areas<\/li>\n        <li>Selective cosmetic regions<\/li>\n        <li>Customer-specified bare metal<\/li>\n      <\/ul>\n    <\/div>\n\n    <div style=\"height:24px\"><\/div>\n\n    <div class=\"grid two\">\n      <article class=\"card\">\n        <h3>Before processing<\/h3>\n        <p>\n          Define final fit, surface roughness, treatment area,\n          masking boundary and measurement locations.\n        <\/p>\n      <\/article>\n\n      <article class=\"card\">\n        <h3>After processing<\/h3>\n        <p>\n          Recheck precision bores, shaft diameters, functional\n          threads, sliding fits and press-fit features.\n        <\/p>\n      <\/article>\n    <\/div>\n\n    <p class=\"note\">\n      Black oxide reproduces the existing surface profile.\n      Tool marks, grinding burns, scratches, pits and material\n      differences remain visible after treatment.\n    <\/p>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5026c9a elementor-widget elementor-widget-html\" data-id=\"5026c9a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section\" id=\"inspection\">\n  <div class=\"wrap media-split\">\n    <div>\n      <p class=\"eyebrow\">Acceptance check<\/p>\n      <h2>Black Oxide Defects and Inspection<\/h2>\n\n      <p>\n        Check coating coverage and dimensions first, followed by\n        color, cleanliness, sealing and packaging.\n      <\/p>\n\n      <div class=\"table-shell\">\n        <table>\n          <thead>\n            <tr>\n              <th>Defect<\/th>\n              <th>Inspection focus<\/th>\n            <\/tr>\n          <\/thead>\n\n          <tbody>\n            <tr>\n              <td data-label=\"Defect\">Uneven or gray color<\/td>\n              <td data-label=\"Inspection focus\">\n                Material, cleaning, bath condition and surface texture\n              <\/td>\n            <\/tr>\n\n            <tr>\n              <td data-label=\"Defect\">Red rust or brown stains<\/td>\n              <td data-label=\"Inspection focus\">\n                Rinsing, sealing, humidity and packaging\n              <\/td>\n            <\/tr>\n\n            <tr>\n              <td data-label=\"Defect\">Bare areas<\/td>\n              <td data-label=\"Inspection focus\">\n                Oil, scale, activation and rack contact\n              <\/td>\n            <\/tr>\n\n            <tr>\n              <td data-label=\"Defect\">Excess black smut<\/td>\n              <td data-label=\"Inspection focus\">\n                Reaction control, bath condition and rinsing\n              <\/td>\n            <\/tr>\n\n            <tr>\n              <td data-label=\"Defect\">Pitting or residue<\/td>\n              <td data-label=\"Inspection focus\">\n                Substrate condition, pretreatment and blind-hole drainage\n              <\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n    <\/div>\n\n    <div class=\"media-card\">\n      <img loading=\"lazy\" decoding=\"async\"\n        src=\"https:\/\/weldomachining.com\/wp-content\/uploads\/2026\/10\/black-oxide-inspection.webp\"\n        alt=\"Dimensional inspection of a black oxide coated precision steel shaft\"\n        width=\"1400\"\n        height=\"933\"\n        loading=\"lazy\">\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-67854a4 elementor-widget elementor-widget-html\" data-id=\"67854a4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"section alt\" id=\"applications\">\n  <div class=\"wrap\">\n    <div class=\"section-head\">\n      <p class=\"eyebrow\">Custom parts<\/p>\n      <h2>Common Black Oxide Parts<\/h2>\n      <p class=\"lead\">\n        Black oxide suits precision ferrous-metal parts requiring\n        a dark finish with minimal buildup.\n      <\/p>\n    <\/div>\n\n    <div class=\"apps\">\n      <article class=\"app\">\n        <h3>Machinery &amp; Automation<\/h3>\n        <p>\n          Locating pins, guide shafts, couplings, rollers,\n          fixtures and mounting hardware.\n        <\/p>\n      <\/article>\n\n      <article class=\"app\">\n        <h3>Automotive &amp; Transmission<\/h3>\n        <p>\n          Gears, splined shafts, bushings, washers and\n          lubricated transmission hardware.\n        <\/p>\n      <\/article>\n\n      <article class=\"app\">\n        <h3>Tooling &amp; Molds<\/h3>\n        <p>\n          Punches, dies, tool holders, mold accessories\n          and precision fixture components.\n        <\/p>\n      <\/article>\n\n      <article class=\"app\">\n        <h3>Optical &amp; Instruments<\/h3>\n        <p>\n          Lens mounts, adjustment rings, internal supports\n          and low-reflective hardware.\n        <\/p>\n      <\/article>\n\n      <article class=\"app\">\n        <h3>Fasteners &amp; Hardware<\/h3>\n        <p>\n          Bolts, nuts, screws, washers, retaining rings\n          and precision pins.\n        <\/p>\n      <\/article>\n\n      <article class=\"app\">\n        <h3>Industrial Equipment<\/h3>\n        <p>\n          Brackets, control parts, internal mechanisms\n          and laboratory tool components.\n        <\/p>\n      <\/article>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0ad85f3 elementor-widget elementor-widget-html\" data-id=\"0ad85f3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<style>\n  #weldo-black-oxide-faq {\n    --bo-primary: #163b55;\n    --bo-primary-dark: #102d42;\n    --bo-accent: #159bb3;\n    --bo-text: #172b38;\n    --bo-muted: #536a75;\n    --bo-line: #dbe5ea;\n    --bo-soft: #f5fafc;\n    --bo-white: #ffffff;\n\n    width: 100%;\n    padding: 80px 0;\n    color: var(--bo-text);\n    background: var(--bo-white);\n    font-family: Arial, Helvetica, sans-serif;\n    font-size: 16px;\n    line-height: 1.65;\n  }\n\n  #weldo-black-oxide-faq,\n  #weldo-black-oxide-faq * {\n    box-sizing: border-box;\n  }\n\n  #weldo-black-oxide-faq .bo-faq-container {\n    width: min(1120px, calc(100% - 40px));\n    margin: 0 auto;\n  }\n\n  #weldo-black-oxide-faq .bo-faq-header {\n    max-width: 720px;\n    margin-bottom: 34px;\n  }\n\n  #weldo-black-oxide-faq .bo-eyebrow {\n    margin: 0 0 10px;\n    color: var(--bo-accent);\n    font-size: 13px;\n    font-weight: 700;\n    letter-spacing: 0.14em;\n    line-height: 1.4;\n    text-transform: uppercase;\n  }\n\n  #weldo-black-oxide-faq h2 {\n    margin: 0;\n    color: var(--bo-primary);\n    font-size: clamp(30px, 4vw, 42px);\n    font-weight: 700;\n    line-height: 1.2;\n    letter-spacing: -0.02em;\n  }\n\n  #weldo-black-oxide-faq .bo-faq-intro {\n    margin: 14px 0 0;\n    color: var(--bo-muted);\n    font-size: 16px;\n    line-height: 1.65;\n  }\n\n  #weldo-black-oxide-faq .bo-faq-list {\n    overflow: hidden;\n    border: 1px solid var(--bo-line);\n    border-radius: 16px;\n    background: var(--bo-white);\n    box-shadow: 0 14px 38px rgba(19, 52, 72, 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position: absolute;\n    top: 50%;\n    right: 24px;\n    width: 28px;\n    height: 28px;\n    color: var(--bo-accent);\n    font-size: 25px;\n    font-weight: 400;\n    line-height: 26px;\n    text-align: center;\n    transform: translateY(-50%);\n  }\n\n  #weldo-black-oxide-faq details[open] summary::after {\n    content: \"\u2212\";\n  }\n\n  #weldo-black-oxide-faq .bo-faq-answer {\n    padding: 0 64px 22px 24px;\n  }\n\n  #weldo-black-oxide-faq .bo-faq-answer p {\n    max-width: 920px;\n    margin: 0;\n    color: var(--bo-muted);\n    font-size: 16px;\n    line-height: 1.7;\n  }\n\n  @media (max-width: 767px) {\n    #weldo-black-oxide-faq {\n      padding: 58px 0;\n    }\n\n    #weldo-black-oxide-faq .bo-faq-container {\n      width: min(100% - 28px, 1120px);\n    }\n\n    #weldo-black-oxide-faq .bo-faq-header {\n      margin-bottom: 26px;\n    }\n\n    #weldo-black-oxide-faq h2 {\n      font-size: 30px;\n    }\n\n    #weldo-black-oxide-faq summary {\n      padding: 18px 52px 18px 18px;\n      font-size: 16px;\n    }\n\n    #weldo-black-oxide-faq summary::after {\n      right: 16px;\n    }\n\n    #weldo-black-oxide-faq .bo-faq-answer {\n      padding: 0 18px 20px;\n    }\n  }\n<\/style>\n\n<section id=\"weldo-black-oxide-faq\" aria-labelledby=\"black-oxide-faq-title\">\n  <div class=\"bo-faq-container\">\n    <div class=\"bo-faq-header\">\n      <p class=\"bo-eyebrow\">Frequently Asked Questions<\/p>\n      <h2 id=\"black-oxide-faq-title\">Black Oxide FAQs<\/h2>\n      <p class=\"bo-faq-intro\">\n        Direct answers about black oxide performance, material compatibility,\n        dimensional effects, rework, and maintenance.\n      <\/p>\n    <\/div>\n\n    <div class=\"bo-faq-list\">\n      <details open>\n        <summary>What is black oxide coating?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Black oxide is a chemical conversion finish that forms a thin black\n            iron-oxide layer on compatible ferrous metals. It adds negligible\n            dimensional buildup, while an oil, wax, or dry sealer provides the\n            required corrosion protection.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>How is steel blackened?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Steel is blackened through cleaning, surface activation, chemical\n            oxidation, rinsing, sealing, and inspection. Hot black oxide commonly\n            uses a controlled alkaline oxidizing bath at approximately 135\u2013150\u00b0C.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Does black oxide rust, and is it corrosion resistant?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Yes, black oxide can rust when the sealing layer is removed or the\n            part remains exposed to moisture. Oil- or wax-sealed black oxide\n            provides light corrosion protection for indoor use, while outdoor\n            and salt-rich environments require a stronger protective finish.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Can stainless steel be black?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Yes, stainless steel can receive a black oxide finish. Its passive\n            chromium-rich surface requires dedicated activation and blackening\n            chemistry selected for the specific stainless steel grade.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Is black oxide conductive?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Black oxide is not a strong electrical insulator and generally\n            preserves metal-to-metal continuity. Sealing oils, waxes,\n            contamination, and contact pressure can increase resistance, so\n            critical grounding surfaces should be tested after finishing.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>What are black oxide drill bits used for?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Black oxide drill bits are used for general-purpose drilling when\n            the drill geometry and cutting parameters match the workpiece. The\n            finish helps retain cutting lubricant and provides light storage\n            corrosion protection.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Will black oxide change part dimensions?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Black oxide creates no appreciable dimensional buildup on standard\n            threads, holes, and CNC-machined features. Ultra-precision fits\n            should still be measured after treatment and sealing.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Can color variation or missed areas be reworked?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Yes, many color and coverage defects can be stripped and reprocessed.\n            The substrate condition and remaining dimensional tolerance should\n            be checked before rework begins.\n          <\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>How should black oxide parts be maintained?<\/summary>\n        <div class=\"bo-faq-answer\">\n          <p>\n            Keep black oxide parts clean, dry, and protected with the specified\n            rust-preventive oil or wax. Remove moisture and fingerprints\n            promptly, then use dry, moisture-controlled packaging for storage.\n          <\/p>\n        <\/div>\n      <\/details>\n    <\/div>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e380f8b elementor-widget elementor-widget-html\" data-id=\"e380f8b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<section class=\"cta\" id=\"quote\">\n  <div class=\"wrap cta-inner\">\n    <div>\n      <h2>Get a Black Oxide Quote<\/h2>\n      <p>\n        Send your drawing and finish requirements for a quote;\n        prototypes and small batches typically ship in 3\u201315 days,\n        while production schedules are confirmed by project.\n      <\/p>\n    <\/div>\n\n    <a class=\"btn\" href=\"https:\/\/weldomachining.com\/file-upload\/\">\n      Upload Your Drawing\n    <\/a>\n  <\/div>\n<\/section>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Precision surface finishing Black Oxide Coating Black oxide gives compatible ferrous-metal parts a low-glare finish with minimal effect on threads, bores and close fits. Minimal dimensional buildup Oil, wax or dry seal Hot and stainless processes Post-finish inspection Upload Drawing for Quote Process selection Which Black Oxide Process Is Right? Select the process according to [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":15030,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-15026","page","type-page","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/pages\/15026","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/comments?post=15026"}],"version-history":[{"count":11,"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/pages\/15026\/revisions"}],"predecessor-version":[{"id":15045,"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/pages\/15026\/revisions\/15045"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/media\/15030"}],"wp:attachment":[{"href":"https:\/\/weldomachining.com\/ko\/wp-json\/wp\/v2\/media?parent=15026"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}