{"product_id":"u-pol-fiberglass-filler-3l-ready-to-mix-polyester-repair-kit-with-bpo-paste-high-build-sandable","title":"U-POL Fiberglass Filler 3L — Ready-to-Mix Polyester Repair Kit with BPO Paste, High-Build \u0026 Sandable","description":"\u003cb\u003eU-POL 0700 Fiberglass Filler (3 L) with BPO paste is a ready-to-mix polyester-based repair system for rebuilding, filling and shaping damaged fiberglass and GRP surfaces.\u003c\/b\u003e\n\u003cp\u003eThis two-part kit combines a high-build, sandable polyester filler with U-POL's benzoyl peroxide (BPO) paste catalyst to deliver controlled cure times and a strong, conformal finish. Formulated for automotive, marine and composite repairs, the filler lays on smoothly, sands to a feather-edge and accepts topcoats. The separate BPO paste lets you adjust working time and ensures thorough crosslinking when mixed at the recommended ratio.\u003c\/p\u003e\n\n\u003ch3\u003eWhat makes this fiberglass filler suitable for structural and cosmetic repairs?\u003c\/h3\u003e\n\u003cp\u003eThe U-POL 0700 filler offers a balance between filling strength and sandability. Its polyester chemistry bonds well to prepared fiberglass laminates and gelcoat, providing a stable base for finishing layers without excessive shrinkage.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eHigh-build formulation for deep fills and profile shaping\u003c\/li\u003e\n  \u003cli\u003eGood adhesion to fiberglass, gelcoat and primed substrates\u003c\/li\u003e\n  \u003cli\u003eControlled shrinkage for consistent finish thickness\u003c\/li\u003e\n  \u003cli\u003eSands easily to a smooth feathered edge\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow do I mix and control cure time with the BPO paste?\u003c\/h3\u003e\n\u003cp\u003eMixing is done by adding the BPO paste to the polyester filler in the manufacturer’s recommended ratio, then stirring until uniform. Adjusting the amount of catalyst and working temperature changes pot life and cure speed—less catalyst = longer working time; more = faster set.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eUse recommended paste weight percent for standard pot life\u003c\/li\u003e\n  \u003cli\u003eWork at moderate temperatures for predictable curing\u003c\/li\u003e\n  \u003cli\u003eMix thoroughly to avoid soft spots or incomplete cure\u003c\/li\u003e\n  \u003cli\u003eWear gloves and avoid skin contact with uncured material\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhich surfaces and prep steps give the best results?\u003c\/h3\u003e\n\u003cp\u003eBest performance comes from mechanically abrading the repair area, removing contaminants, and wiping with a suitable solvent. For delaminations or holes, backing with a glass mat and building layers of filler creates a strong repair.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAbrade to sound substrate; remove wax, oil and loose material\u003c\/li\u003e\n  \u003cli\u003eUse glass mat or woven roving for structural fills under the filler\u003c\/li\u003e\n  \u003cli\u003eApply in layers, allowing each to tack before adding more\u003c\/li\u003e\n  \u003cli\u003eFinish with progressive sanding grits before priming and topcoat\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat safety and handling practices should I follow?\u003c\/h3\u003e\n\u003cp\u003eBoth polyester fillers and BPO catalysts are reactive chemicals; handle with care, use PPE, and ensure good ventilation. Store the BPO paste in a cool, dry place away from heat sources and incompatible materials.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eWear nitrile gloves, safety goggles and a respirator during mixing\u003c\/li\u003e\n  \u003cli\u003eWork in well-ventilated areas to minimize styrene fumes\u003c\/li\u003e\n  \u003cli\u003eClean tools immediately after use to prevent cured build-up\u003c\/li\u003e\n  \u003cli\u003eFollow local regulations for disposal of unused catalyst and resin\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: U-POL 0700 Fiberglass Filler with BPO paste is intended for professional bodyshops, marine repair technicians and advanced DIYers who need a dependable polyester repair system. It suits projects from gelcoat repairs and fairing compounds to medium structural rebuilds where a sandable, paint-ready surface is required. If you require epoxy-level structural bonding or underwater repairs, consider a purpose-built epoxy system instead; for conventional fiberglass and GRP repairs, this kit is a practical, widely used solution that balances strength, workability and finishability.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can U-POL 0700 be used on gelcoat surfaces?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes—after scuffing and cleaning, the filler bonds well to gelcoat and sands smooth for repainting.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: What mixing ratio should I use with the BPO paste?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Follow the manufacturer's ratio on the product label; adjust catalyst amount slightly for warmer or cooler conditions.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"U-POL","offers":[{"title":"Default Title","offer_id":48080235823262,"sku":"B00NOIJW7W","price":123.03,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/u-pol-0700-front-of-packaging.jpg?v=1785779968","url":"https:\/\/northtrailauto.ca\/products\/u-pol-fiberglass-filler-3l-ready-to-mix-polyester-repair-kit-with-bpo-paste-high-build-sandable","provider":"North Trail Auto","version":"1.0","type":"link"}