{"id":7960,"date":"2025-12-15T09:00:00","date_gmt":"2025-12-15T09:00:00","guid":{"rendered":"https:\/\/uplastech.com\/skirting-profile-extrusion\/"},"modified":"2025-12-15T09:00:00","modified_gmt":"2025-12-15T09:00:00","slug":"skirting-profile-extrusion","status":"publish","type":"post","link":"https:\/\/uplastech.com\/ru\/skirting-profile-extrusion\/","title":{"rendered":"Skirting Profile Extrusion: Surface Finish and the Joint That Shows"},"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\/10\/skirting-profile-extrusion.jpg\" alt=\"Gloss against melt temperature, and surface roughness against die land length\" width=\"1536\" height=\"909\"><figcaption>Gloss rises from 22 to 58 units between 180 C and 220 C and saturates, while roughness falls from 2.8 to 1.2 micrometres as the die land goes from 8 to 24 mm.<\/figcaption><\/figure>\n<div class=\"toc\"><\/div>\n<h2 id=\"job\">A skirting board is a finish, not a structure<\/h2>\n<p>A skirting profile does three things: it covers the joint between the wall and the floor, it protects the bottom of the wall from scuffs, and it gives the room a horizontal line. None of those is structural, which is why the section is thin, the material is cheap and the surface is the whole product.<\/p>\n<p>That changes the design priorities. A structural profile is designed for stiffness and the surface is secondary. A skirting is designed for the surface and the stiffness only has to be enough to stay straight on the wall. A 1.5 mm wall on a 100 mm high board is normal, and it is stiff enough because the board is fixed to the wall along its length.<\/p>\n<p>The consequence is that almost every complaint about a skirting profile is a surface complaint: it is too glossy or not glossy enough, it has a visible flow line, it shows a scratch, or the joint has opened. None of them is about strength.<\/p>\n<h2 id=\"gloss\">Gloss comes from the melt<\/h2>\n<p>Surface gloss on a PVC profile is set by how well the melt replicates the die and calibrator surface. A melt that is too cold has not relaxed its memory, so it leaves the die with a faint skin irregularity and the surface reads as semi-matte. A hotter melt flows into the surface detail and reads as gloss.<\/p>\n<p>Measured at 60 degrees, the gloss goes from 22 units at a 180 C melt to 34 at 190, 46 at 200, 55 at 210 and 58 at 220. The last 10 degrees buy three units, which is below the threshold most people can see, and they cost thermal stability margin and a risk of degradation.<\/p>\n<p>So the practical window is 195 to 210 C for a matte-to-satin finish and 210 to 220 C for a full gloss. Below 195 C the surface shows flow lines and die marks; above 220 C the compound starts to yellow and the die builds plate-out faster.<\/p>\n<table>\n<thead>\n<tr>\n<th>\u0422\u0435\u043c\u043f\u0435\u0440\u0430\u0442\u0443\u0440\u0430 \u0440\u0430\u0441\u043f\u043b\u0430\u0432\u0430<\/th>\n<th>Gloss at 60 degrees<\/th>\n<th>\u041e\u0442\u0434\u0435\u043b\u043a\u0430<\/th>\n<th>\u0420\u0438\u0441\u043a<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>180 C<\/td>\n<td>22 GU<\/td>\n<td>Matte<\/td>\n<td>Flow lines, die marks visible<\/td>\n<\/tr>\n<tr>\n<td>190 C<\/td>\n<td>34 GU<\/td>\n<td>Semi-matte<\/td>\n<td>Some die lines<\/td>\n<\/tr>\n<tr>\n<td>200 C<\/td>\n<td>46 GU<\/td>\n<td>Satin<\/td>\n<td>Balanced<\/td>\n<\/tr>\n<tr>\n<td>210 C<\/td>\n<td>55 GU<\/td>\n<td>Gloss<\/td>\n<td>Plate-out starts<\/td>\n<\/tr>\n<tr>\n<td>220 C<\/td>\n<td>58 GU<\/td>\n<td>High gloss<\/td>\n<td>Yellowing, degradation<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 \u2014 Melt temperature against measured gloss, and what each band costs.<\/p>\n<h2 id=\"land\">Die land and calibration set roughness<\/h2>\n<p>The die land is the straight section at the end of the flow channel, and its job is to let the melt relax and to build up enough pressure to fill the die evenly. A short land gives a rough surface because the melt is still accelerating as it leaves; a long land gives a smooth one because the flow has become fully developed.<\/p>\n<p>Measured as Ra, the surface roughness falls from 2.8 micrometres at an 8 mm land to 2.0 at 12, 1.5 at 16, 1.3 at 20 and 1.2 at 24. The gain is steep up to 16 mm and then almost flat, which is the usual shape for a land length curve.<\/p>\n<p>A long land costs pressure, and pressure costs output. Doubling the land from 12 to 24 mm roughly doubles the pressure drop across it, which on a small extruder can be the difference between running at 12 metres a minute and 9. The balance is a land of 16 to 20 mm for most skirting sections.<\/p>\n<p>The calibrator matters as much as the die. A polished chrome calibrator with a good vacuum distribution will hold the finish the die delivers; a worn one with scratches will imprint them on every metre. Calibrator wear is the most common cause of a surface that degrades over months without any change in the process settings.<\/p>\n<h2 id=\"joint\">The joint that shows<\/h2>\n<p>PVC moves. The linear expansion coefficient is around 5.5 x 10 to the minus 5 per kelvin, so a 4 m skirting board grows by 4.4 mm over a 20 K rise. That is more than enough to open a mitre, close a butt joint and push a board out of its end stop.<\/p>\n<p>The traditional answer is to fix the board at one point and let it move at the ends, with the movement hidden behind an internal corner piece or a flexible sealant joint. The wrong answer, which is also the common one, is to pin both ends and fill the mitre with decorator's caulk, which then cracks within a season.<\/p>\n<p>For a butt joint between two lengths, a loose tongue or a purpose-made connector absorbs the movement and keeps the face flush. For a mitre, a moulded corner piece is better than a cut mitre, because the corner piece can be bonded to one board and slide over the other.<\/p>\n<table>\n<thead>\n<tr>\n<th>Joint type<\/th>\n<th>Movement allowed<\/th>\n<th>\u0412\u043d\u0435\u0448\u043d\u0438\u0439 \u0432\u0438\u0434<\/th>\n<th>Where it is used<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Cut mitre, filled<\/td>\n<td>None<\/td>\n<td>Cracks within a season<\/td>\n<td>Should be avoided<\/td>\n<\/tr>\n<tr>\n<td>Cut mitre, bonded one side<\/td>\n<td>Partial<\/td>\n<td>Good until the bond fails<\/td>\n<td>Light domestic<\/td>\n<\/tr>\n<tr>\n<td>Moulded corner piece<\/td>\n<td>Full on one board<\/td>\n<td>Clean, consistent<\/td>\n<td>The usual commercial detail<\/td>\n<\/tr>\n<tr>\n<td>Butt with connector<\/td>\n<td>Full<\/td>\n<td>Visible joint line<\/td>\n<td>Long runs<\/td>\n<\/tr>\n<tr>\n<td>Butt with shadow gap<\/td>\n<td>Full<\/td>\n<td>Deliberate reveal<\/td>\n<td>Modern interiors<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 \u2014 Joint details, and how much movement each one tolerates.<\/p>\n<div class=\"callout\">Design the joint for 1 mm of movement per metre of board. A skirting that is fixed rigidly at both ends will either bow off the wall or open at the mitre, and no amount of filler will stop it.<\/div>\n<h2 id=\"wall\">Wall thickness and weight<\/h2>\n<p>Skirting is sold by the metre and priced by weight, so wall thickness is the main cost lever. A 1.5 mm wall on a 100 mm board weighs about 0.55 kilograms per metre in rigid PVC; a 2.0 mm wall weighs 0.73. On a house with 60 metres of skirting that is 11 kilograms of material, which is real money at compound prices.<\/p>\n<p>The floor is set by handling and fixing rather than by load. Below about 1.2 mm the board dents when it is handled, the fixing nails pull through, and the profile will not stay straight against an uneven wall. Above 2.0 mm the extra material buys nothing that anyone can see.<\/p>\n<p>A hollow-back section is the usual compromise: the visible face is 1.5 to 1.8 mm, the back is relieved so that the board sits flat against an uneven wall, and the weight comes down by 20 to 30 percent. The relief also gives the cable route that half the installations end up needing.<\/p>\n<h2 id=\"specify\">What to specify<\/h2>\n<p>Skirting is often bought on a sample and a price, and the specification is whatever the sample happened to be. Five lines prevent that.<\/p>\n<ul>\n<li>Gloss target in units at 60 degrees, with a tolerance of plus or minus 5.<\/li>\n<li>Surface roughness Ra, or a visual standard agreed against a master sample.<\/li>\n<li>Wall thickness at the face, and whether the back is relieved.<\/li>\n<li>Colour match against a master, including the light source it is judged under.<\/li>\n<li>Joint system: corner pieces, connectors, and the movement allowance.<\/li>\n<\/ul>\n<p>The gloss and colour together are what a customer sees, and they are the two that drift first when a compound changes. A master sample kept in a drawer is worth more than any number on a drawing, provided somebody actually compares against it.<\/p>\n<div class=\"faq\">\n<h3>How do I get a glossier PVC skirting?<\/h3>\n<p>Raise the melt temperature. Gloss goes from 22 units at 180 C to 55 at 210 C, then flattens. Above 220 C the compound yellows and the die plates out.<\/p>\n<h3>Why does my skirting have a rough surface?<\/h3>\n<p>Usually a die land that is too short, or a worn calibrator. Roughness falls from 2.8 to 1.2 micrometres as the land goes from 8 to 24 mm.<\/p>\n<h3>Why do skirting mitres open?<\/h3>\n<p>PVC expands about 5.5 x 10 to the minus 5 per kelvin, so a 4 m board moves 4.4 mm over a 20 K swing. A mitre that is pinned at both ends has nowhere to go and cracks.<\/p>\n<h3>What wall thickness should skirting have?<\/h3>\n<p>1.5 to 1.8 mm on the face. Below 1.2 mm it dents in handling and the fixings pull through; above 2.0 mm the extra material is invisible.<\/p>\n<h3>Can skirting be bent around a curved wall?<\/h3>\n<p>Only with a purpose-made flexible profile or by kerfing the back. Rigid PVC skirting will kink rather than curve, and the kink is permanent.<\/p>\n<h3>Should skirting be glued or nailed?<\/h3>\n<p>Fixed mechanically at one point and allowed to move elsewhere, with adhesive only where the substrate is stable. Gluing along the whole length locks the board and guarantees a joint failure.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">Specifying a skirting or trim profile?<\/p>\n<p>Send the section and the finish you need. We will quote the die, the land length and the compound, and tell you which gloss level the process can hold consistently.<\/p>\n<p><a class=\"btn\" href=\"https:\/\/uplastech.com\/ru\/%d0%bf%d0%b2%d1%85-%d0%bf%d1%80%d0%be%d1%84%d0%b8%d0%bb%d0%b8\/\">Talk to a profile engineer<\/a>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/ru\/corner-bead-profile\/\">Corner Bead and Trim Profiles: Thin Walls That Still Hold Shape<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ru\/decking-profile-extrusion\/\">Decking Profile Extrusion: Slip, Expansion and Hidden Fixing<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ru\/window-profile-reinforcement\/\">Window Profile Reinforcement: Steel, Fibre or Nothing<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ru\/cable-trunking-profile\/\">Cable Trunking Profile: Wall Thickness, Impact and Cable Fill<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ru\/%d0%bf%d0%b2%d1%85-%d0%bf%d1%80%d0%be%d1%84%d0%b8%d0%bb%d0%b8\/\">PVC Profiles: Extrusion, Tooling and Tolerances<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Gloss climbs from 22 to 58 units as the melt goes from 180 C to 220 C and then stops. Roughness falls from 2.8 to 1.2 micrometres as die land goes from 8 to 24 mm. Neither fixes the joint, which is a movement problem.<\/p>","protected":false},"author":1,"featured_media":7959,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"Skirting Profile Extrusion: Finish and Joints","_seopress_titles_desc":"PVC skirting profile extrusion: gloss against melt temperature, roughness against die land length, why mitre joints open, expansion and fixing, wall thickness a","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"17","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"","footnotes":""},"categories":[17],"tags":[],"class_list":["post-7960","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-plastic-extrusion-process"],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/posts\/7960","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/comments?post=7960"}],"version-history":[{"count":0,"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/posts\/7960\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/media\/7959"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/media?parent=7960"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/categories?post=7960"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/ru\/wp-json\/wp\/v2\/tags?post=7960"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}