SI 598 Black Silicone Gasket Maker
RTV silicone · US · manufacturer-sourced
How long does Loctite (Henkel) SI 598 Black Silicone Gasket Maker take to dry?
Short answer
Gasket-sealing stages
Assemble, wait, then fill and pressurize
- Apply the RTV silicone to clean, dry flanges
- Assemble within the stated time
- Fill and run only after the stated cure
This product’s stated stages Quoted at 77°F and 5% humidity
- Tack-free25 minutes
- Full cure3 days
Worth noticing: Tack-free at 25 minutes; full cure at 3 days.
Common mistake: Adding fluid or pressure before the gasket has cured; leaks follow.
Bond-strength path
Assembly, handling and full load are different stages
Time the gasket cure
Your countdown
Stated times
- Tack-free25 minutes
- Full cure3 days
From Loctite (Henkel) data sheet · checked 2026-10-25. Anything not listed isn’t stated by the manufacturer.
Manufacturer website: loctiteproducts.com
Conditions & fine print
- Stated conditions: 77°F (25°C) and 5% relative humidity
- RTV silicone cures from moisture in the air, so cure is slower in dry air and in thick sections. Follow the current data sheet.
- Region US. Formulas can differ between countries; check your container.
- Tack-free: At 25°C (77°F) and 50 ± 5% relative humidity.
- Full cure: Moisture cure; cured-material properties are reported after 7 days at 25°C.
- Entered from the cited manufacturer documentation. Check the current label for the exact formula and region. Report outdated information
- Actual results depend on preparation, thickness, ventilation, temperature, humidity, mixing and substrate.
Confirm this is your product
Closely named formulas, colors and regional versions can use different times. Match these details to your container before starting a countdown.
- Exact listing
- Loctite (Henkel) SI 598 Black Silicone Gasket Maker
- Variant
- RTV silicone
- Region
- US
- Listed use
- gasket maker, rtv silicone, flange sealing
- Timed stages recorded
- tack free, full cure
- Source checked
- 2026-10-25
Documentation: Technical data sheet copy · November 2018, distributor copy
Condition attached to the stated time: At 25°C (77°F) and 50 ± 5% relative humidity.
About this product
The black counterpart to Loctite 587. Its tack-free figure is a single upper bound (25 minutes or less) against 587's 10 to 50 minute range, but both reach full performance in 72 hours.
Using this specific product
Loctite (Henkel) SI 598 Black Silicone Gasket Maker is listed here as the RTV silicone version for gasket maker, rtv silicone, and flange sealing. For using this product, the useful question is not simply whether the surface looks finished—it is whether the exact next-action milestone shown above has been reached.
Before you start
- Confirm the package says RTV silicone; related versions can use different timing.
- For gasket maker, rtv silicone, and flange sealing, pay particular attention to the exact variant, preparation and environmental conditions.
- At 25°C (77°F) and 50 ± 5% relative humidity. Moisture cure; cured-material properties are reported after 7 days at 25°C.
How to check readiness
Check the real material or treated area at the slowest location before the next step. The data sheet gives a tack-free time of 25 minutes or less. Reserve full cure for demanding use, chemicals, washing, immersion or load—not merely gentle handling.
Avoid this mistake
The first visible change is not always the manufacturer’s final-use milestone.
Compare with similar products
- Compare with Permatex Ultra Grey Gasket MakerTack-free: 1 h there, 25 min here.
- Compare with Permatex Water Pump & Thermostat RTV Silicone GasketTack-free: 1 h there, 25 min here.
Questions
How long does this product take to dry?
Loctite (Henkel) states: The data sheet gives a tack-free time of 25 minutes or less. Conditions: At 25°C (77°F) and 50 ± 5% relative humidity.. The data sheet says full performance properties will develop over 72 hours. Conditions: Moisture cure; cured-material properties are reported after 7 days at 25°C.. These are the manufacturer’s stated times, not a guarantee.
Is Loctite 598 faster to tack-free than Loctite 587?
On the data sheets, 598 is at 25 minutes or less and 587 is 10 to 50 minutes, both at 25°C and 50% humidity. Both say full performance properties develop over 72 hours.
How long does this product take to fully cure?
Loctite (Henkel) states: The data sheet says full performance properties will develop over 72 hours. Conditions: Moisture cure; cured-material properties are reported after 7 days at 25°C.. These are the manufacturer’s stated times, not a guarantee.
What affects how long this product takes to dry or cure?
RTV silicone cures from moisture in the air, so cure is slower in dry air and in thick sections. Follow the current data sheet. Follow the product label for your conditions.