{"id":17869,"date":"2026-04-19T12:04:16","date_gmt":"2026-04-19T06:34:16","guid":{"rendered":"https:\/\/aluminiummagazine.com\/mag\/?p=17869"},"modified":"2026-04-19T12:04:17","modified_gmt":"2026-04-19T06:34:17","slug":"aluminium-stearate-waterproofing-soap-guide","status":"publish","type":"post","link":"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/aluminium-stearate-waterproofing-soap-guide.html","title":{"rendered":"Aluminium Stearate (Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083): The Complete Guide"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Aluminium stearate is a <strong>metallic soap<\/strong> \u2013 a salt formed from aluminum and stearic acid (a common fatty acid). It appears as a white, fine, fluffy powder. Unlike reactive aluminum salts (chloride, nitrate), aluminum stearate is mild, water\u2011repellent, and used primarily as a thickening agent, lubricant, and waterproofing additive in industrial and cosmetic formulations.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">1. <strong>Basic Identification<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Chemical Formula:<\/strong> Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083<\/li>\n\n\n\n<li><strong>Alternative Names:<\/strong> Aluminium(III) tristearate, aluminum soap, stearic acid aluminum salt<\/li>\n\n\n\n<li><strong>Molecular Weight:<\/strong> 877.35 g\/mol<\/li>\n\n\n\n<li><strong>CAS Number:<\/strong> 637-12-7<\/li>\n\n\n\n<li><strong>Appearance:<\/strong> White, fine, fluffy powder<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">2. <strong>Physical Properties<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Aluminium Stearate<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~115\u202f\u00b0C (239\u202f\u00b0F) (decomposes)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Density<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~1.01 g\/cm\u00b3<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Bulk Density<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Very low (fluffy, lightweight)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Solubility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Insoluble in water; soluble in hot oils, turpentine, and aromatic solvents<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Hydrophobicity<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Strongly water\u2011repellent<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Aluminium stearate is a soft, greasy\u2011feeling powder. It is non\u2011hygroscopic and stable in air.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">3. <strong>Chemical Behavior &amp; Synthesis<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">3.1 Hydrophobic Nature<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The long hydrocarbon chains (C\u2081\u2088H\u2083\u2085) from stearic acid make the molecule strongly <strong>lipophilic<\/strong> (oil\u2011loving) and <strong>hydrophobic<\/strong> (water\u2011hating). When added to paints or coatings, it aligns at surfaces to repel water.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">3.2 Synthesis<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Prepared by reacting aluminum salts (e.g., aluminum sulfate) with sodium stearate (soap) in a double\u2011displacement reaction:<\/p>\n\n\n\n<p class=\"has-large-font-size wp-block-paragraph\"><strong>Al\u2082(SO\u2084)\u2083 + 6 C\u2081\u2087H\u2083\u2085COONa \u2192 2 Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083 + 3 Na\u2082SO\u2084<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The precipitate is washed and dried to yield the fluffy white powder.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">4. <strong>Industrial &amp; Cosmetic Applications<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">4.1 Waterproofing Agent<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Aluminum stearate is added to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Concrete and mortar<\/strong> to reduce water penetration<\/li>\n\n\n\n<li><strong>Textiles and paper<\/strong> to impart water resistance<\/li>\n\n\n\n<li><strong>Paints and varnishes<\/strong> as a flatting agent and to prevent pigment settling<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">4.2 Thickener for Lubricating Greases<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">When mixed with mineral oils, aluminium stearate forms a stable gel \u2013 a <strong>grease<\/strong> \u2013 used in high\u2011temperature and water\u2011resistant lubricants.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4.3 Cosmetics and Pharmaceuticals<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Acts as a <strong>thickener<\/strong> in creams, lotions, and ointments<\/li>\n\n\n\n<li>Used as a <strong>gelling agent<\/strong> in antiperspirants and deodorants (where it helps suspend active ingredients)<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">4.4 Anticaking Agent<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Added to powders (e.g., in food packaging or industrial blends) to prevent clumping.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">5. <strong>Safety &amp; Hazard Management<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>General Safety:<\/strong> Aluminium stearate is considered <strong>low toxicity<\/strong> and safe for cosmetic use. It is not an oxidizer, not flammable, and not corrosive.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Route of Exposure<\/th><th>Effect<\/th><\/tr><\/thead><tbody><tr><td><strong>Inhalation<\/strong><\/td><td>Fine dust may cause mild mechanical irritation. Use dust mask.<\/td><\/tr><tr><td><strong>Skin Contact<\/strong><\/td><td>Non\u2011irritating; may feel greasy.<\/td><\/tr><tr><td><strong>Eye Contact<\/strong><\/td><td>Mechanical irritation (dust). Flush with water.<\/td><\/tr><tr><td><strong>Ingestion<\/strong><\/td><td>Low toxicity (used in some food\u2011contact applications).<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>PPE:<\/strong> Dust mask, safety glasses, standard gloves (minimal hazard).<br><strong>Storage:<\/strong> Normal dry storage; avoid excessive dust accumulation.<br><strong>Disposal:<\/strong> Non\u2011hazardous; can be disposed as solid waste.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">6. Environmental Impact<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Aluminium stearate is derived from natural fatty acids and is <strong>biodegradable<\/strong>. It does not persist in soil or water. No significant ecotoxicity concerns.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">7. Comparison with Other Aluminium Compounds<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Compound<\/th><th class=\"has-text-align-center\" data-align=\"center\">Formula<\/th><th class=\"has-text-align-center\" data-align=\"center\">Primary Nature<\/th><th>Primary Use<\/th><\/tr><\/thead><tbody><tr><td><strong>Aluminium Stearate<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Metallic soap (hydrophobic)<\/td><td>Waterproofing, grease thickener<\/td><\/tr><tr><td><strong>Aluminium Hydroxide<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al(OH)\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Amphoteric powder<\/td><td>Antacid, flame retardant<\/td><\/tr><tr><td><strong>Aluminium Chloride<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">AlCl\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Lewis acid<\/td><td>Catalyst, antiperspirant<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">8. <strong>Frequently Asked Questions<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Is aluminum stearate a \u201csoap\u201d that cleans?<\/strong><br>A: No. \u201cMetallic soap\u201d refers to its chemical structure (salt of a fatty acid). It does not lather or clean; it repels water and thickens oils.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Is it safe in cosmetics?<\/strong><br>A: Yes. Aluminum stearate is widely used in creams, lotions, and antiperspirants at low concentrations. It is not absorbed significantly through skin.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Can I mix aluminum stearate with water?<\/strong><br>A: It will not dissolve. It floats and clumps. It must be dissolved in hot oil or solvent to be effective.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">9. <strong>Summary Data Sheet<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Value<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Chemical Name<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Aluminum Stearate<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Formula<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Appearance<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">White, fluffy powder<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~115\u202f\u00b0C<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Defining Trait<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Hydrophobic, greasy texture<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Primary Utility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Waterproofing, grease thickener, cosmetic additive<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Hazard Note<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Low toxicity; dust nuisance only<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/p><script>document.addEventListener(\"DOMContentLoaded\",function(){\n        if(window.innerWidth <= 768){\n            if (\"immediate\" === \"delay\") {\n                setTimeout(function(){document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\")},0);\n            } else if (\"immediate\" === \"scroll\") {\n                window.addEventListener(\"scroll\",function(){\n                    let s=window.scrollY\/(document.body.scrollHeight-window.innerHeight);\n                    if(s>0.1){\n                        document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n                    }\n                });\n            } else {\n                document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n            }\n        } else {\n            document.querySelectorAll(\".pai-ad\").forEach(el=>el.remove());\n        }\n    });<\/script>","protected":false},"excerpt":{"rendered":"<p>Aluminium stearate is a metallic soap \u2013 a salt formed from aluminum and stearic acid (a common fatty acid). It appears as a white, fine, fluffy powder. Unlike reactive aluminum salts (chloride, nitrate), aluminum stearate is mild, water\u2011repellent, and used primarily as a thickening agent, lubricant, and waterproofing additive in industrial and cosmetic formulations. 1. &#8230; <a title=\"Aluminium Stearate (Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083): The Complete Guide\" class=\"read-more\" href=\"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/aluminium-stearate-waterproofing-soap-guide.html\" aria-label=\"Read more about Aluminium Stearate (Al(C\u2081\u2088H\u2083\u2085O\u2082)\u2083): The Complete Guide\">Read more<\/a><\/p>\n","protected":false},"author":12,"featured_media":17996,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4155],"tags":[4141,4142],"class_list":["post-17869","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-compounds","tag-aluminium-compounds","tag-aluminum-formula"],"_links":{"self":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17869","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/comments?post=17869"}],"version-history":[{"count":0,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17869\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media\/17996"}],"wp:attachment":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media?parent=17869"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/categories?post=17869"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/tags?post=17869"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}