Bondit HT30 High Temperature Silicone Sealant 310ml

Bondit HT30 is a ready-to-use high temperature silicone sealant formulated to handle the kind of heat that would ruin a standard sealant within weeks. Based on an acetic cure silicone system, HT30 permanently withstands temperatures up to 250°C once cured, with short-term resistance up to 300°C. That makes it a practical choice anywhere heat is a constant rather than an occasional factor.

Standard silicone sealants are fine for bathrooms and window frames. Put them near a boiler flue, an engine bay, or an industrial oven and the results are predictably poor. HT30 exists specifically to close that gap. It does not soften, crack, or lose adhesion at temperatures that would degrade ordinary silicones, and it carries UV resistance and weatherproofing for applications that also face the elements.

HT30 is available in black and red. The red variant is particularly common in automotive and industrial settings where the colour helps identify the sealant type at a glance. Both perform identically in service.

Where Bondit HT30 High Temperature Silicone Gets Used

HT30 bonds and seals on a wide range of substrates including glass, ceramic tiles, enamel, epoxy paint, metals, nylon, ABS plastics, and polyester. On some plastics and non-porous metals, a primer may improve adhesion, particularly where the joint will be submerged or subject to humid heat over long periods.

The sealant is mildew resistant, which matters in applications where heat and moisture combine, such as around boiler connections or industrial pipework. It is not a gasket replacement for high-pressure joints, but for sealing, bonding, and weatherproofing in hot environments, it covers a broad range of practical situations.

Acetic Cure: What That Means in Practice

HT30 uses acetic cure chemistry, which means it releases acetic acid as it cures. This is the same system used in most standard silicone sealants and produces the familiar vinegar-like smell during the curing process. It cures reliably at room temperature with atmospheric moisture. The trade-off is that acetic cure silicones are not suitable for use on reactive metals such as copper or brass, or on natural stone, without checking compatibility first. On glass, ceramic, enamel, steel, and painted surfaces, adhesion is strong and consistent.

For anyone working on heating systems, automotive applications, or light industrial plant, Bondit HT30 is a straightforward, cost-effective solution. At the price point it sits at, it makes sense to keep a tube in the van for the jobs that catch you out, because nothing quite focuses the mind like finishing a boiler installation and realising you have standard silicone to hand.