Mastercool Aluminum Repair Epoxy Paste 90935 — Alum Bond, Machinable & Heat-Resistant

Whether you're a mechanic, HVAC technician, fabricator or DIYer, Alum Bond delivers a heavy-duty metal repair solution when replacing a part isn't practical. This industrial-strength polymer compound combines metallic aluminum filler with a durable resin system to produce repairs that cure hard, resist heat, and can be drilled, sanded or tapped like metal. Its non-sag, paste-like consistency makes it easy to place into cavities, vertical surfaces and irregular cast areas while giving you time to shape and finish before it sets.

How strong and durable is this repair compound?

Alum Bond is engineered for demanding service environments, offering high compressive and tensile strength that restores structural integrity to damaged aluminum parts. Cured repairs withstand mechanical loads and routine service stresses found in automotive and industrial equipment.

• Approximately 8,600 PSI compressive strength for load-bearing repairs
• Around 3,500 PSI tensile strength to resist pull-apart forces
• Heat-resistant to approximately 250°F (121°C) after full cure
• Formulated to resist oil, coolant and common workshop fluids when cured

Can I machine or finish the repair after it cures?

Yes—once fully cured Alum Bond behaves much like a soft metal composite and accepts standard metalworking operations. That makes it possible to re-establish threads, true mating surfaces, or drill holes without replacing the entire component.

• Drill, sand, file and tap cured material with conventional tools
• Use common machining speeds and cutters for light finishing work
• Finish surfaces to match surrounding geometry for gaskets or fittings
• Allows repair of threads and bores on blocked or cracked parts

How is it applied and how much working time do I have?

Alum Bond comes as a two-part paste that is mixed before application; its thick, non-sag texture is designed for controlled placement on vertical or overhead surfaces. Cure speed varies with temperature, so you get a predictable working window to shape and tool the compound before it hardens.

• Mix the resin and hardener thoroughly to a uniform color for best strength
• Non-sag paste stays in cavities and vertical repairs for accurate filling
• Working time depends on ambient temperature—follow label guidance for optimal shaping
• Allow full cure time before machining or exposing to high heat

What types of parts and defects is Alum Bond best for?

This product is targeted at aluminum castings and assemblies where porosity, blow holes, cracks or minor structural damage occur. It is commonly used when replacement parts are costly, obsolete or require downtime to source.

• Radiators, evaporator housings, heater cores and HVAC cast components
• Engine blocks, valve covers, oil pans and accessory housings
• Tanks, pumps, valve bodies and castings with surface defects or porosity
• Restoration of threads, flange faces and mating surfaces after repair

Who is this for? Technicians and advanced hobbyists who need a long-lasting, machinable metal repair without replacing expensive aluminum parts will find Mastercool 90935 Alum Bond especially useful. It suits professional shops performing field or bench repairs, HVAC and refrigeration service techs repairing housings and tanks, and vehicle restorers working with cast components. For best results, follow mixing, application and cure instructions and use proper safety precautions in a well-ventilated workspace.