High-Temperature Door-Gasket Retrofit for an Industrial Oven — DOWSIL™ 736 Heat Resistant Sealant

November 2, 2026

A tunnel-type industrial curing oven on a sheet-metal painting line operates continuously at approximately 230–250°C. The original asbestos-rope door gasket had cracked and shrunk, causing hot-air leakage, higher ambient temperature near the door, and increased energy consumption. The maintenance team required an alternative sealant that:

Withstands long-term temperatures around 260°C
Is non-slumping and can be applied on vertical and overhead seams
Offers relevant compliance credentials for adjacent food-compliant production areas
Is supplied as a one-part material, cures at room temperature, and enables short maintenance downtime

Why DOWSIL™ 736

Requirement	Reference
Long-term high-temperature resistance	Continuous service up to 260°C; intermittent exposure up to 315°C
Non-slumping, suitable for overhead application	Non-slumping paste; Flow/Slump = Nil
One-part, easy to dispense	One-part silicone; extrusion rate 390 g/min @90 psi
Regulatory references	Complies with 21 CFR 177.2600 for incidental food contact; NSF Standard 51 listed for direct food contact; UL listed; designed to meet MIL-A-46106 Rev.B
Ambient cure conditions	Cures upon exposure to atmospheric moisture; skin-over time ~17 minutes, cures to a rubbery solid within 24 hours for beads ≤3 mm (1/8 inch) at 25°C and 50% RH

Application Procedure

Shut down the oven and allow it to cool completely. Remove the aged gasket, then degrease and clean metal surfaces with a suitable solvent. Ensure all surfaces are dry before application.
Verify substrate compatibility. Avoid non-recommended substrates including copper, brass, zinc, carbon steel, galvanized iron, PTFE, polyethylene, polypropylene and impregnated wood. The door frame in this project consists of stainless steel and aluminum, which are not listed as restricted substrates.
Optional: Apply a thin layer of DOWSIL™ 1200 Prime Coat or DOWSIL™ P5200 Adhesion Promoter to non-rubber surfaces to improve adhesion. Note: these primers are flammable and must not be used on food-contact surfaces.
Dispense the sealant evenly along the door flange using a caulking gun. Maintain sealant thickness at or below 3 mm (1/8 inch). Tool the bead with a spatula within 5 minutes after application.
Allow ambient cure. At 25°C and 50% relative humidity, the sealant forms a tack-free skin within approximately 17 minutes and fully cures to a rubbery solid in 24 hours. Cure time will extend under lower humidity conditions.
Maintain adequate ventilation during curing. The acetic acid odor released during cure will dissipate once curing is complete.

Results

Surface temperature around the oven door decreased by approximately 8–12°C, with no visible hot-air leakage.
After six months of continuous operation with peak temperature reaching 255°C, the sealant bead showed no cracking, slumping or debonding.
Total retrofit duration from oven shutdown to production restart was less than 28 hours, including surface preparation, sealant application and ambient cure.
The compliance statements documented in the TDS supported EHS documentation, which is beneficial for facilities adjacent to food-processing areas referencing NSF Standard 51.

Cautions (Lessons Learned)

Do not use on copper, brass, galvanized steel, PTFE, PP or PE. The TDS warns of poor adhesion or potential corrosion of sensitive metals caused by acetic acid released during cure.
Do not apply excessively thick beads (>3 mm) or use in fully confined joints, as atmospheric moisture is required for proper cure.
Vertical and overhead application is a key advantage of this product, as it will not sag or run.
If workshop relative humidity falls below 30%, extend the cure time accordingly; do not force early heat-up of the oven.

Takeaway

For TDS-listed applications such as industrial oven door seams, heating-element encapsulation and bag-filter flanges on smoke stacks, DOWSIL™ 736 is a practical one-part solution offering continuous service at 260°C, non-slumping performance for overhead use, and relevant FDA/NSF/UL/MIL references — provided sensitive metals and fully confined thick beads are avoided.

Persona de Contacto :	ouyang
Teléfono :	+86 13510063180