“RTV” and “gasket maker” are often used as if they mean the same thing. They do not. RTV silicone is one type of gasket maker, and there are other liquid sealing chemistries that outperform it for specific joints. Knowing the difference leads to better seal selection.

Gasket Makers: The Broad Category

A gasket maker, also called a formed-in-place or liquid gasket, is a compound applied as a liquid or paste that cures in place between two mating surfaces. Instead of a pre-cut shape, it conforms to every scratch and imperfection, creating a continuous seal that usually beats a cut gasket on conformity and leak prevention. The main industrial types are:

• RTV silicone gasket makers
• Anaerobic gasket makers
• UV-curable gasket makers, including dual-cure variants

RTV Silicone Gasket Makers

RTV stands for room temperature vulcanizing. These grades cure at ambient temperature by reacting with atmospheric moisture.

• Cure: Skin-over in minutes, full cure over hours to a few days depending on humidity, temperature, and bead thickness.
• Flexibility: Cures into a flexible rubber that absorbs vibration and differential thermal expansion. This matters on engine components and plastic housings, where the joint sees movement. The stress that drives seal fatigue is covered in this guide to how CTE mismatch causes adhesive bond failure.
• Gap filling: Handles larger, irregular, or warped flanges well.
• Temperature range: Many grades cover roughly -50 to +250 degC, with high-temperature versions going higher.
• Chemical resistance: Generally good against water, coolants, and many oils; formulation-dependent.
• Typical use: Engine covers and oil pans, pumps, electrical enclosures, and HVAC systems.

Anaerobic Gasket Makers

Unlike RTV, anaerobics cure in the absence of air and in contact with active metal ions on bare metal surfaces. They stay liquid until confined between parts.

• Rigid, high-strength seal: Forms a tough thermoset within the joint.
• Thin-gap sealing: Ideal for machined metal-to-metal flanges with gaps under about 0.5 mm, allowing true metal-to-metal contact that improves bolt retention and stiffness.
• Chemical resistance: Strong against aggressive oils and industrial fluids.
• Fast fixture: Handling strength develops quickly.
• Typical use: Gearboxes, engine block half-casings, pump housings, hydraulic systems.

UV-Curable Gasket Makers

These liquids cure in seconds under UV light of a specific wavelength and intensity.

• Very fast cure: Seconds, enabling immediate part handling.
• Automation friendly: Well suited to automated dispensing on high-volume lines. Head selection is covered in the guide to the Incure CDM UV conveyor by line speed and part width.
• Clean and clear: Many grades cure clear and solvent-free.
• Flexibility options: Formulated rigid or flexible as needed.
• Limitation: Needs a transparent substrate or direct line-of-sight for the light. Dual-cure versions add a secondary moisture or heat cure for shadowed areas.
• Typical use: Electronics enclosures, display assemblies, and sensor housings where speed and clean sealing matter.

How Incure Supports Gasket Maker Selection

Incure supplies gasket maker options across all three chemistries, with grades matched to temperature range, oil and chemical exposure, gap size, joint dynamics, and cure-speed targets. Our team analyzes the joint design, materials, operating environment, and line-speed requirement to recommend a chemistry, and advises on surface preparation, dispensing equipment, and cure parameters.

The rigid-versus-flexible trade-off that separates anaerobics from RTV is the same one covered in the comparison of UV glue versus epoxy for heavy-duty repairs. To discuss a specific joint, contact us at Email Us.

A Decision Framework

Work through the joint in this order. First, is the gap effectively zero, with two rigid machined metal faces? If so, an anaerobic sealant gives the strongest, stiffest seal and true metal-to-metal contact. Second, does the line need parts to move within seconds, and can light reach the bead or a transparent part? If so, a UV-curable grade fits, with a dual-cure version if any of the bead is shadowed. Third, is the flange stamped, warped, or spanning dissimilar materials, or does the joint flex and vibrate in service? That is RTV silicone territory, chosen for flexibility and gap filling. When two answers point in different directions, the more flexible or more forgiving option usually wins, because a rigid sealant in a moving joint fails faster than a flexible sealant in a rigid one.

Where Each Struggles

RTV silicone is a poor choice for tight machined joints where its thickness prevents correct bolt torque, and standard grades are not suited to continuous fuel contact. Anaerobics will not cure across a wide gap, will not bond inactive surfaces without a primer, and are brittle where a joint needs to flex. UV-curable grades cannot cure what the light cannot reach, so a fully enclosed opaque joint rules them out unless a secondary cure is designed in. Knowing the failure mode of each chemistry is as useful as knowing its strengths.

Practical Advice

• Define the application: Identify joint type, gap size, temperature range, fluid exposure, pressure, and required cure speed before choosing.
• Consult the data sheet: Check specifications, cure times, and chemical compatibility.
• Prepare surfaces: Clean, dry, oil-free flanges are required for every type.
• Test in real conditions: Validate the seal under conditions that match actual service before full-scale use.

Conclusion

RTV silicone is a widely used and effective gasket maker, but it is one member of a family that also includes rigid anaerobics for tight metal joints and fast UV-curable grades for automated lines. Matching the chemistry to the joint, rather than defaulting to RTV, is what produces reliable seals and efficient assembly.

To select the right gasket maker for a joint, Contact Our Team with your flange type, gap, operating conditions, and production speed.

Visit www.incurelab.com for more information.