A standard cyanoacrylate bond can fail well before the substrate itself is under real thermal stress — the adhesive’s own glass transition point, not the parts being joined, is often the actual limiting factor. Incure’s Heat-Resist™ line addresses that directly with five rubber-toughened, single-component ethyl cyanoacrylate grades built specifically for thermal shock resistance, organized around viscosity and substrate scope rather than one shared “high-temp CA” spec. Rubber toughening is the shared chemistry behind the whole line’s thermal-shock resistance: a standard, unmodified cyanoacrylate cures into a rigid, brittle film that cracks under the stress of rapid temperature swings, while the rubber-modified formulation flexes enough to absorb that stress at the bond line instead of transmitting it straight into a fracture.
Two Viscosity Pairs, Each Available in Black or Clear
Heat-Resist™ 311 and 340 share the same high viscosity (2,000–3,000 cP) and the same broad substrate scope across plastics, rubber, metal, fiberglass, ceramic, and wood — the widest bonding range in the line — plus the highest temperature ceiling at 145°C. The two differ only in color: 311 is black, 340 is clear, letting a line pick based on whether bond-line visibility matters for inspection or cosmetic reasons rather than on any mechanical difference. Heat-Resist™ 319 and 328 form a second matched pair at medium viscosity (400–600 cP), again split by color — 319 black, 328 clear — but with a narrower substrate focus on plastics and metal rather than the full six-substrate range of the 311/340 pair, and a slightly lower temperature ceiling at 135–140°C. Choosing between the two pairs comes down to whether the joint spans the broader substrate range or stays within plastic-to-metal bonding, since the medium-viscosity pair doesn’t carry the same rubber, fiberglass, ceramic, or wood bonding claim.
320 Is the Thinnest, Fastest-Wicking Grade in the Line
Heat-Resist™ 320 stands alone as the thinnest grade at just 260–370 cP, thin enough to wick by capillary action into an already-assembled tight joint rather than requiring the parts to be coated before mating — the same low-viscosity wicking behavior found in Incure’s UV-cure gasket lines, just applied to cyanoacrylate chemistry here. It shares the medium-viscosity pair’s plastic-and-metal substrate focus, but its temperature ceiling drops slightly further to 135°C, the lowest in the line. That combination makes 320 the grade to reach for on fine-gap assembly work where a thicker grade would sit on the surface rather than flow into the joint, provided the application doesn’t need the higher-viscosity grades’ extra 10°C of thermal headroom. Because 320 only comes in black, a line that needs both wicking viscosity and bond-line clarity for inspection has to choose one property over the other — no clear, low-viscosity grade exists in this line the way one does at the medium- and high-viscosity tiers.
Email Us with your substrate combination, joint geometry, and service temperature, and Incure’s engineers can confirm which Heat-Resist™ grade actually fits.
Shared Chemical Resistance and Bond Strength Across the Line
All five grades deliver the same headline bond strength figures — up to 5,200 PSI on steel, 3,800 PSI on polycarbonate, 3,200 PSI on both aluminum and PVC, 2,500 PSI on ABS, and 2,200 PSI on rubber — and the same resistance to alcohol, petrol, aromatic hydrocarbons, and diluted aqueous acids and bases, so chemical exposure resistance isn’t a differentiator between grades the way viscosity and substrate scope are. Two grades carry an additional qualification worth flagging specifically: 319 and 340 are formulated to meet the MIL-A-46050C military specification, relevant for defense and aerospace assemblies that require that qualification as a purchasing or compliance requirement, while 311, 320, and 328 don’t carry that same designation. Since 319 and 340 sit in different viscosity tiers — 319 at medium viscosity, 340 at the line’s highest — a defense or aerospace project that needs the MIL-A-46050C qualification still has a genuine viscosity choice to make between the two rather than being locked into one specific grade by the compliance requirement alone.
Where the Line Fits
Multi-substrate assembly work spanning plastics, rubber, metal, fiberglass, ceramic, and wood in the same joint favors 311 or 340, chosen by whether bond-line color matters for the application. Plastic-to-metal bonding that doesn’t need the wider substrate range favors 319 or 328 on the same color basis. Fine-gap, already-assembled joints benefit from 320’s wicking viscosity over any of the other four grades’ thicker consistency. Defense and aerospace assemblies with a military-specification requirement should specify 319 or 340 specifically rather than defaulting to whichever grade otherwise fits the substrate and viscosity need. Facilities running Incure’s Epo-Weld™ high-temperature epoxy line for structural bonds at higher service temperatures can add Heat-Resist™ cyanoacrylate for faster-fixturing joints within its own 135–145°C range, where cyanoacrylate’s near-instant fixture time is a genuine advantage over epoxy’s longer cure schedule.
Contact Our Team to confirm the Heat-Resist™ grade for your substrate and service temperature.
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