HIGHHEAT SYRINGE - 25ML

HighHeat is rated for repairs up to 550 F once fully cured. J-B Weld publishes a single maximum for the syringe rather than separate continuous and intermittent numbers, so treat 550 F as a peak and keep sustained service comfortably below it. Once cured it also stays serviceable at low temperatures, down to around -40 F, which covers most outdoor and automotive use.

HighHeat sets in about 1 hour and reaches full cure in 24 hours at room temperature. You can accelerate the cure to roughly 1 hour by holding the repair at 250 F. Mix the two parts 1:1 until the color is uniform. Do not put the part into service or expose it to heat until the full cure time has passed.

No. HighHeat is an epoxy and it will burn where flame touches it directly, so it is not suitable for fire pit mesh, burner screens or the inside of a firebox. It handles radiant and conducted heat up to its 550 F rating, not open flame. For repairs in the fire zone, have the part welded instead.

No. Pressure and fluid will work in behind the repair and lift it, and a failure on a pressurized line is a safety problem, not just a leak. J-B Weld support recommends replacing the line or having it professionally welded. HighHeat is better suited to unpressurized repairs such as small muffler holes, brackets and filling on metal, ceramic and fiberglass.

Yes. Once fully cured, HighHeat can be shaped, filed, sanded and drilled. Its tensile strength is 4730 PSI, and it contains a small amount of steel for strength but is not electrically conductive when cured. Wait for the full cure before machining it; working the repair early will tear it loose from the substrate.

HighHeat bonds metal, aluminum, ceramic, brick, stone, fiberglass and many plastics. The surface must be clean, dry and scuffed; it will not adhere well to a wet or slick surface, so drain a coolant line before you apply it. It does not bond polypropylene or EPDM rubber. Sand with medium paper and wipe with acetone for the best grip.

Store the syringe nose-up rather than lying on its side. Keeping it upright helps prevent the tips from becoming contaminated, so the product stays ready for your next repair.