{"id":8474,"date":"2026-06-03T09:00:00","date_gmt":"2026-06-03T08:00:00","guid":{"rendered":"https:\/\/uplastech.com\/silicone-laser-marking\/"},"modified":"2026-11-02T02:27:34","modified_gmt":"2026-11-02T02:27:34","slug":"silicone-laser-marking","status":"publish","type":"post","link":"https:\/\/uplastech.com\/nl\/silicone-laser-marking\/","title":{"rendered":"Laser Marking Silicone: Contrast Without a Label"},"content":{"rendered":"<style>\n.upl-blog{font-size:17px;line-height:1.78;color:#1f2937}\n.upl-blog p{margin:0 0 18px}\n.upl-blog h2{font-size:26px;line-height:1.3;color:#0b2b33;margin:46px 0 14px;font-weight:700;letter-spacing:-.015em}\n.upl-blog h3{font-size:19.5px;color:#0d3b47;margin:28px 0 10px;font-weight:700}\n.upl-blog ul,.upl-blog ol{margin:0 0 20px;padding-left:22px}\n.upl-blog li{margin:0 0 9px}\n.upl-blog figure{margin:0 0 34px}\n.upl-blog figure img{width:100%;height:auto;display:block;border-radius:10px}\n.upl-blog figcaption{font-size:13px;color:#6b7280;margin-top:10px;line-height:1.5}\n.upl-blog .toc{background:none;border:0;border-radius:0;padding:0;margin:0 0 34px}\n.upl-blog .toc .lwptoc{margin:0}\n.upl-blog .toc h4{margin:0 0 10px;font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:#0d5563}\n.upl-blog .toc ol{margin:0;padding-left:18px;font-size:14.5px}\n.upl-blog .toc li{margin-bottom:6px}\n.upl-blog table{width:100%;border-collapse:collapse;font-size:14.5px;margin:0 0 10px}\n.upl-blog th{background:#0d3b47;color:#fff;text-align:left;padding:11px 13px;font-weight:600;font-size:13.5px;border:0}\n.upl-blog td{padding:11px 13px;border:0;border-bottom:1px solid #e8ebed;vertical-align:top}\n.upl-blog tbody tr:nth-child(even){background:#fafbfc}\n.upl-blog .tablecap{font-size:12.5px;color:#6b7280;margin:0 0 30px}\n.upl-blog .myth{background:#fff8ef;border:1px solid #f6ddbd;border-radius:8px;padding:16px 20px;margin:0 0 26px;font-size:15.5px}\n.upl-blog .myth b{color:#a85c10}\n.upl-blog .callout{background:#f2f8f9;border-radius:8px;padding:18px 22px;margin:0 0 26px;font-size:15.5px;border-left:3px solid #14707f}\n.upl-blog .faq h3{border-top:1px solid #eceff1;padding-top:22px;margin-top:0;font-size:18px}\n.upl-blog .faq h3:first-of-type{border-top:0;padding-top:0}\n.upl-blog .cta{background:linear-gradient(135deg,#0b2b33,#0d5563);color:#fff;border-radius:12px;padding:34px;margin:48px 0 30px}\n.upl-blog .cta h2,.upl-blog .cta .cta-h{color:#fff;margin:0 0 10px;font-size:24px;font-weight:700;line-height:1.3}\n.upl-blog .cta p{color:#c9dee3;margin:0 0 20px;font-size:16px}\n.upl-blog .btn{display:inline-block;background:#e07a1f;color:#fff;text-decoration:none;font-weight:700;padding:13px 26px;border-radius:8px;font-size:15.5px}\n.upl-blog .rel{border-top:1px solid #e8ebed;margin-top:40px;padding-top:26px}\n.upl-blog .rel h4{font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:#6b7280;margin:0 0 14px}\n.upl-blog .rel ul{list-style:none;padding:0;margin:0}\n.upl-blog .rel li{padding:11px 0;border-bottom:1px dashed #e8ebed}\n.upl-blog .rel a{text-decoration:none;font-weight:600;font-size:15.5px}\n@media(max-width:640px){.upl-blog h2{font-size:22px}.upl-blog table{font-size:13px}.upl-blog .cta{padding:24px}}\n\/* \u5355\u7bc7\u9875\u9690\u85cf WhatsApp \u95ee\u5019\u5361\uff0c\u53ea\u4fdd\u7559\u5706\u5f62\u6c14\u6ce1\uff0c\u907f\u514d\u906e\u6321\u4fa7\u680f\u8be2\u76d8\u63d0\u4ea4\u6309\u94ae\u3002\n   \u6ce8\u610f\uff1aClick to Chat \u7684\u70b9\u51fb\u903b\u8f91\u662f\u300c\u95ee\u5019\u5361\u5143\u7d20\u5b58\u5728\u5c31\u4e0d\u8df3\u8f6c\u300d\uff0c\u53ea\u9760 CSS \u9690\u85cf\u4f1a\u8ba9\u6c14\u6ce1\u53d8\u6210\u6b7b\u94fe\u63a5\u3002\n   Code Snippets #9\u300cUPL single post: WhatsApp bubble jumps straight to chat\u300d\u8d1f\u8d23\u628a\u8be5\u8282\u70b9\u4ece DOM \u79fb\u9664\uff0c\n   \u4e0b\u9762\u8fd9\u6761 CSS \u53ea\u662f\u79fb\u9664\u524d\u7684\u89c6\u89c9\u515c\u5e95\u3002\u5220 #9 \u524d\u5fc5\u987b\u5148\u5220\u8fd9\u6761\u89c4\u5219\u3002 *\/\nbody.single-post .ht_ctc_chat_greetings_box{display:none !important}\n<\/style>\n<div class=\"upl-blog\">\n<figure>\n<img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/11\/silicone-laser-marking.jpg\" alt=\"A laser marking head with a red aiming beam scanning across a black silicone keypad on a bench, a tray of finished parts beside it\" width=\"1536\" height=\"909\"><figcaption>A red aiming beam, a black part, and a mark that has to survive a thousand wipes.<\/figcaption><\/figure>\n<div class=\"toc\"><\/div>\n<h2 id=\"why\">Why silicone is hard to mark<\/h2>\n<p>Laser marking on a thermoplastic usually works by carbonising or foaming a thin surface layer, and both of those need the material to absorb the laser wavelength and to degrade in a predictable way. Silicone absorbs weakly in the near infrared, where most industrial marking lasers operate, and it degrades into a silica-rich residue rather than a dark char.<\/p>\n<p>The result is a mark that is pale rather than dark on most silicone, and it comes from a combination of surface roughening and localized crosslinking. On a white or translucent silicone the mark reads as a slightly darker grey; on a black silicone it reads as a light grey or white, which is the more useful direction.<\/p>\n<p>Pigmented silicone behaves differently again. The pigment absorbs some of the energy, so a black part marks more readily than a white one at the same settings, and a coloured part may show a colour shift rather than a contrast change. This is why a setting developed on a black keypad does not transfer to a white gasket.<\/p>\n<p>The practical consequence is that laser marking silicone is a material specific process. There is no universal setting, and a supplier who quotes a parameter set without asking about the compound is quoting a guess.<\/p>\n<h2 id=\"how\">How a laser marks silicone<\/h2>\n<p>Two laser types dominate. Fibre lasers at 1064 nm are the workhorse: fast, reliable and cheap to run, and they mark black and dark silicone well. UV lasers at 355 nm are absorbed more strongly by silicone and produce a finer, higher contrast mark, at roughly three times the cost per watt and a slower marking speed.<\/p>\n<p>The mechanism on a fibre laser is mostly thermal. The surface reaches a temperature where the polymer chains break and the silicone oxidises to a silica-like layer, which scatters light and appears pale. If the energy is too high the layer becomes thick and powdery, and it rubs off, which is the failure mode that catches people out.<\/p>\n<p>A UV laser works more by photochemical bond breaking than by heating, so the mark is thinner, sharper and less prone to the powdery layer. On small medical and electronic parts where the mark has to be legible at 1 mm character height, the UV laser is usually the only way to get the resolution.<\/p>\n<p>Focal position matters more than most operators expect. Silicone is soft and slightly compliant, so a part that is not held flat sits at a varying distance from the lens, and the mark varies in contrast across the part. A simple vacuum fixture solves it and is often the difference between a process that works and one that does not.<\/p>\n<h2 id=\"power\">Power, frequency and the scorching limit<\/h2>\n<p>Contrast rises with power up to a point and then falls. The chart on the left shows the pattern on a black 60 Shore A keypad: 16 delta E at 3 W, 41 at 8 W, then 38 at 12 W, 30 at 16 W and 19 at 20 W. The fall is not a measurement error; it is the mark layer becoming thick, rough and light-scattering in a way that reads as a scorch rather than a mark.<\/p>\n<p>The optimum at 8 W is not a universal number, but the shape of the curve is. Every silicone compound has a power at which contrast peaks, and running above it produces a mark that looks acceptable on the bench and fails a rub test a week later, because the powdery layer is not bonded to anything.<\/p>\n<p>Frequency is the second variable and it is usually set once and forgotten. Higher frequency means more pulses per millimetre, which gives a smoother mark and more heat accumulation. Lower frequency gives a coarser, more abraded looking mark with less heat. On silicone, the middle of the laser's range is usually right, with the power doing the work.<\/p>\n<p>Marking speed is the third and it behaves like an inverse of power. Halving the speed doubles the energy per unit area, which is the same as doubling the power, with the same scorching limit. A process that is at the edge of scorching at one speed will be over it at half that speed, and speed changes are often made without re-checking the mark.<\/p>\n<figure>\n<img decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/11\/silicone-laser-marking-chart.jpg\" alt=\"Mark contrast rising to 41 delta E at 8 watts and falling to 19 at 20 watts, with a line chart showing laser marks retaining 93 percent after 500 rub cycles against 22 percent for pad printed ink\" width=\"1536\" height=\"909\"><figcaption>Left: contrast peaks at 8 W and falls as the mark scorches. Right: a laser mark wears far more slowly than an ink.<\/figcaption><\/figure>\n<h2 id=\"contrast\">Contrast is not depth<\/h2>\n<p>A deep mark is not a good mark. Depth comes from removing material, and on a seal or a keypad a mark that is 50 micrometres deep is a surface defect that can start a crack or leak. The aim is a shallow surface change with high optical contrast, not an engraved character.<\/p>\n<p>The measurement that matters is contrast, expressed as a delta E between the mark and the surrounding surface, or as a simple grey level difference on a monochrome camera. A delta E above about 25 is legible in normal light; above 35 is legible under low light and in a photograph. Below 15 the mark is only visible at an angle.<\/p>\n<p>Depth can be checked with a profilometer or a focus variation microscope, and it should be, at least once per material. A mark that is 5 to 15 micrometres deep with a delta E of 35 is ideal. A mark that is 40 micrometres deep with the same contrast is doing damage for no benefit.<\/p>\n<p>There is also a cosmetic question that the numbers do not capture. A laser mark on silicone has a slightly frosted appearance that reads as engraved rather than printed, and some customers prefer it and some do not. That is worth settling with a sample before the process is validated.<\/p>\n<h2 id=\"durability\">Durability compared with ink<\/h2>\n<p>The reason to laser mark rather than pad print is durability, and the difference is large. The right hand chart shows mark remaining against rub cycles on the same part: a laser mark at 8 W retains 93 percent after 500 cycles, while a pad printed mark retains 22 percent. The ink wears progressively; the laser mark barely moves.<\/p>\n<p>The mechanism is that a laser mark is part of the material. There is no interface to fail, so the mark cannot delaminate. It can still be abraded away if the surrounding silicone is abraded away, but that takes a level of wear that would destroy the part anyway.<\/p>\n<p>The comparison is not entirely fair, because a well applied pad print on a properly treated surface can reach 90 percent after 200 cycles. But that requires the surface treatment, the ink mix and the cure to all be right, and it fails silently when one of them drifts. The laser mark has fewer variables.<\/p>\n<p>Where ink still wins is colour. A laser mark on silicone is monochrome, either pale on dark or dark on pale. A multi-colour logo, a coloured date code or a mark that has to match a brand colour needs ink, and no amount of laser development will produce it.<\/p>\n<h2 id=\"program\">Programming a mark that reads<\/h2>\n<p>Character height is the first constraint. On silicone, a laser mark needs at least 0.8 mm character height to be legible, and 1.2 mm is comfortable. Below 0.8 mm the mark is a smudge regardless of the laser, because the surface roughening that produces the contrast is larger than the stroke width.<\/p>\n<p>Line spacing and fill matter as much as the font. A hatched fill with 0.02 mm spacing produces a solid mark with high contrast; a single pass outline produces a thin, low contrast line. Most marking software defaults to an outline, and changing to a fill is often the single biggest improvement available.<\/p>\n<p>The mark should also be positioned to avoid the areas that flex. A mark across a living hinge or a sealing lip will crack the surface layer when the part flexes, and the crack propagates from the mark. Moving the mark 2 mm away from the flex zone is usually enough.<\/p>\n<table>\n<thead>\n<tr>\n<th>Parameter<\/th>\n<th>Effect<\/th>\n<th>Starting point for silicone<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Power<\/td>\n<td>Contrast rises then falls<\/td>\n<td>8 to 12 W on a 20 W fibre laser<\/td>\n<\/tr>\n<tr>\n<td>Frequency<\/td>\n<td>Mark smoothness and heat<\/td>\n<td>20 to 40 kHz<\/td>\n<\/tr>\n<tr>\n<td>Snelheid<\/td>\n<td>Inverse of power<\/td>\n<td>300 to 800 mm\/s<\/td>\n<\/tr>\n<tr>\n<td>Fill spacing<\/td>\n<td>Contrast and solidity<\/td>\n<td>0.02 to 0.03 mm<\/td>\n<\/tr>\n<tr>\n<td>Focal offset<\/td>\n<td>Line width and contrast<\/td>\n<td>At the surface, or 0.5 mm below<\/td>\n<\/tr>\n<tr>\n<td>Passes<\/td>\n<td>Contrast, at the risk of depth<\/td>\n<td>One pass, then evaluate<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 \u2014 Starting parameters for a fibre laser on black silicone<\/p>\n<h2 id=\"validate\">Validation and the rub test<\/h2>\n<p>A laser mark that passes a visual check on the day of production can still fail in the field, for the same reason a pad print can: the mark layer may be powdery and unbonded. The rub test is the same one used for ink, and it should be applied to laser marks too.<\/p>\n<p>The test that matters for silicone is the alcohol wipe, because medical and consumer products are cleaned. Fifty wipes with an isopropanol pad, then re-measure the contrast. A mark that loses more than 15 percent of its contrast is marginal; one that loses more than 30 percent will not survive a customer's cleaning regime.<\/p>\n<p>The second test is flex. Bend the part through its service range twenty times and inspect the mark for cracks. A mark that cracks is too deep or too close to a flex zone, and the fix is a parameter change rather than a new material.<\/p>\n<table>\n<thead>\n<tr>\n<th>Test<\/th>\n<th>Methode<\/th>\n<th>Pass criterion<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Contrast<\/td>\n<td>Delta E against the surrounding surface<\/td>\n<td>Above 25, ideally above 35<\/td>\n<\/tr>\n<tr>\n<td>Depth<\/td>\n<td>Profilometer or focus variation<\/td>\n<td>5 to 15 micrometres<\/td>\n<\/tr>\n<tr>\n<td>Alcohol wipe<\/td>\n<td>50 wipes with isopropanol, then re-measure<\/td>\n<td>Less than 15 % contrast loss<\/td>\n<\/tr>\n<tr>\n<td>Rub<\/td>\n<td>Eraser, 500 g, 500 cycles<\/td>\n<td>Above 85 % remaining<\/td>\n<\/tr>\n<tr>\n<td>Flex<\/td>\n<td>20 cycles through the service range<\/td>\n<td>No cracking at the mark<\/td>\n<\/tr>\n<tr>\n<td>Legibility<\/td>\n<td>Read at 300 mm in normal light<\/td>\n<td>All characters clear<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 \u2014 A validation set for a laser marked silicone part<\/p>\n<p>The parts that fail validation are usually failing on depth or on focal position rather than on the laser itself. A mark that is too deep is a power setting, a mark that varies across the part is a fixturing problem, and a mark that is faint everywhere is a focal offset. All three are fixable without changing the equipment, which is why validation belongs before the process is released rather than after.<\/p>\n<div class=\"faq\">\n<h3>Can every silicone be laser marked?<\/h3>\n<p>Most can, but the contrast varies enormously with the compound and the pigment. Black and dark grey silicone marks well with a fibre laser; white and translucent silicone marks faintly and often needs a UV laser or an additive. Always test the actual compound before committing to the process.<\/p>\n<h3>Why does more power give a worse mark?<\/h3>\n<p>Above the optimum the surface layer becomes thick, rough and powdery. It scatters light in a way that reads as a scorch rather than a mark, and it is not bonded to the material underneath, so it rubs off. Contrast peaks and then falls as power rises.<\/p>\n<h3>Is a laser mark as durable as a printed one?<\/h3>\n<p>More durable in most cases. A laser mark is part of the material with no interface to delaminate, and it retains over 90 percent of its contrast after 500 rub cycles where a pad print retains about 20 percent. A well applied print on a properly treated surface can approach it, but with far more process variables.<\/p>\n<h3>Can I laser mark a coloured silicone part?<\/h3>\n<p>Yes, but the mark is usually a shade of the base colour rather than a contrasting colour. A red part may mark darker red or brown. If the mark has to be a different colour, ink is the only option.<\/p>\n<h3>What character height can I achieve?<\/h3>\n<p>About 0.8 mm minimum for legibility, and 1.2 mm for comfort. Below 0.8 mm the surface roughening that creates the contrast is comparable to the stroke width and the characters become a smudge. A UV laser can go slightly smaller than a fibre laser.<\/p>\n<h3>Does laser marking affect the mechanical properties?<\/h3>\n<p>At the depths used for marking, no. The affected layer is 5 to 15 micrometres deep, which is a fraction of a percent of the part thickness. At excessive power the affected layer grows and can act as a crack initiator, particularly on a flexing part.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">Marking that has to survive cleaning?<\/p>\n<p>Send the part, the compound and the cleaning regime. We will tell you whether laser marking will hold and what contrast to expect.<\/p>\n<p><a class=\"btn\" href=\"https:\/\/uplastech.com\/nl\/silicone-rubber\/\">Ask about laser marking<\/a>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/nl\/silicone-printing-pad\/\">Pad Printing on Silicone: Ink, Cure and the Mark That Rubs Off<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/nl\/silicone-surface-treatment\/\">Silicone Surface Treatment: Plasma, Corona and Printability<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/nl\/silicone-post-processing\/\">Silicone Post-Processing: Deflashing, Washing and Assembly<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/nl\/silicone-keypad-molding\/\">Silicone Keypad Moulding: From Tool to Tactile Feel<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/nl\/silicone-yellowing\/\">Silicone Yellowing: Why White Parts Turn Cream<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Silicone does not absorb laser energy the way a thermoplastic does, so marking it is a different problem. The mark comes from a surface change rather than a colour change, and the window between a readable mark and a scorched one is narrow.<\/p>","protected":false},"author":1,"featured_media":8472,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[39],"tags":[],"class_list":["post-8474","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-silicone-rubber-products"],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/posts\/8474","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/comments?post=8474"}],"version-history":[{"count":1,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/posts\/8474\/revisions"}],"predecessor-version":[{"id":8861,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/posts\/8474\/revisions\/8861"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/media\/8472"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/media?parent=8474"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/categories?post=8474"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/nl\/wp-json\/wp\/v2\/tags?post=8474"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}