Technical Foundation
What Is a Gasket Sealants and Maker?
Formed-in-place gasket sealants replace or supplement a cut gasket by curing directly between two mating surfaces to fill surface irregularities and create a seal. RTV (room temperature vulcanizing) silicone cures on exposure to atmospheric moisture and remains flexible after curing, making it forgiving of surface flex and thermal cycling — common in valve covers, oil pans and general low-to-moderate pressure sealing. Anaerobic sealants cure only in the absence of oxygen, between two closely mated metal surfaces, and cure to a harder, more rigid bond suited to flanges with tighter tolerances and higher pressure or fluid exposure.
Chemistry selection depends on the fluids the joint will be exposed to (oil, coolant, fuel, hydraulic fluid all have different compatibility requirements) and the operating temperature range, since a sealant rated to 400°F will degrade and lose its seal well before that temperature if the actual joint runs hotter. Surface prep — removing old gasket material and oil residue — is critical for both chemistries, since sealant adhesion depends on a clean, properly prepared mating surface.
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| Spec | What It Means | Why It Matters |
|---|---|---|
| Chemistry | RTV silicone, anaerobic, formed-in-place | RTV suits flexible/moving joints; anaerobic suits rigid, closely-mated metal flanges |
| Cure Mechanism | Moisture-cure (RTV) vs. oxygen-exclusion cure (anaerobic) | Determines cure time and whether the sealant cures fully in a tight, low-oxygen flange gap |
| Temperature Range | Product-specific, commonly -65°F to 500°F+ | Must exceed the joint's actual maximum operating temperature with margin |
| Fluid Compatibility | Oil, coolant, fuel, hydraulic fluid resistant grades | Using an incompatible sealant chemistry against a given fluid can cause it to degrade or fail to seal |
| Flange Gap Tolerance | Anaerobic requires tight, well-mated metal surfaces | Anaerobic sealants don't cure properly or fill large gaps the way RTV silicone can |
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Applications
Where Gasket Sealants and Makers Get Used
Gasket sealants and makers are specified anywhere two mating surfaces need a formed, cured seal instead of or in addition to a pre-cut gasket.
Automotive & Engine Repair
RTV silicone sealing valve covers, oil pans and timing covers subject to thermal cycling and flex.
Hydraulic & Fluid Power Systems
Anaerobic sealants sealing rigid metal flanges on hydraulic manifolds and pump housings.
Industrial Equipment Maintenance
Formed-in-place gasket sealants replacing cut gaskets on equipment housings during rebuilds.
Marine Engine & Equipment Service
High-temperature and fluid-resistant sealants specified for marine engine and drivetrain sealing.
Heavy Equipment & Fleet Maintenance
Gasket sealants used in field repairs where a pre-cut gasket isn't readily available or practical.
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Gasket Sealants and Makers Brands in the Catalogue
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FAQ
Gasket Sealants and Makers Questions, Answered
When should I use RTV silicone versus an anaerobic sealant?
RTV silicone suits joints that flex or move slightly during operation, such as valve covers and oil pans, since it stays flexible after curing. Anaerobic sealants suit rigid, closely mated metal flanges under higher pressure, since they cure to a harder bond but require tight surface contact and low oxygen exposure to cure properly.
Why isn't my anaerobic sealant curing?
Anaerobic sealants cure only in the absence of oxygen between two closely mated surfaces — if the flange gap is too large or the surfaces aren't making close contact, oxygen exposure will prevent or slow curing significantly. Confirm surfaces are properly mated and torqued to spec.
Does gasket sealant chemistry need to match the fluid in the system?
Yes — check the sealant's stated fluid compatibility against what the joint will actually be exposed to (oil, coolant, fuel, hydraulic fluid), since a sealant not rated for a specific fluid can soften, degrade or fail to maintain a seal over time.
How important is surface prep before applying gasket sealant?
Very — sealant adhesion depends on a clean surface free of old gasket material, oil film and debris; skipping proper surface prep is one of the most common causes of a formed-in-place gasket failing prematurely.
Can gasket sealant be used instead of a cut gasket entirely?
In many low-to-moderate pressure applications, yes — that's the purpose of a formed-in-place sealant. For high-pressure, high-temperature or safety-critical joints, follow the equipment manufacturer's specification, since some applications still call for a cut gasket with sealant used only as an additional aid.
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