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Vacseal – High Vacuum Leak Sealant Vacseal – High Vacuum Leak Sealant 1

Vacseal – High Vacuum Leak Sealant

Typical Uses

  • Glass to Metal Interfaces
  • Electrical Feedthroughs
  • Flanges
  • Bellows
  • Viewports


Vacseal is a silicone resin used primarily for sealing leaks in high and ultra-high vacuum systems. At 50°C the weight loss after 175 hours in vacuum is only 0.000005 grams/cm2 compared to 0.01 grams/cm2 for epoxy compounds. Residual gas analysis indicates no evidence of hydrocarbons or other contamination arising from Vacseal used on systems capable of attaining ultimate pressures of 1 x 10-12 Torr.

Vacseal will seal leaks as large as 4-micron liters per second on systems under evacuation. The sealant will repair larger leaks if the system is at atmospheric pressure. The vapor pressure of the sealant is highest when initially sprayed or painted on the system. The vapor pressure can be reduced to nearly that of most metals by simply curing with a modest amount of heat.

Vacseal is extremely useful as a cement for sealing all kinds of optical windows and CRT glass to wire feedthroughs. It will substantially reduce the IR reflectivity of metals and will produce higher emissivity levels for better heat transfer.

Vacseal has expansive application as an adhesive at cryogenic temperatures as well as good radiation resistance. The sealant's durability will survive the environment of space without adverse effect on the product or the spacecraft itself. Available in both aerosol cans and bottles KL-5 can withstand repeated temperature cycling from liquid helium temperatures to 450°C over long intervals of time.

Vacseal eliminates leaks in both metal and glass components of ultra-high vacuum systems. Its superior electrical resistivity makes it extremely useful for making permanent repairs in all types of glass vacuum gauge tubes and preventing the flow of gases through faulty seals around electrodes.

Directions for Use

APPLICATION: Prior to using the sealant, surface dirt should be removed from the suspected area. Any hydrocarbon solvent is recommended for removal of greasy surface dirt. New systems can be sprayed or painted directly.

CURING: Recommended cure times are 30 minutes at 200°C, 15 minutes at 250°C. Curing can also be affected at room temperature but requires a period of several days.

REMOVAL: In the event it is desirable to remove the sealant, cured sealant is easily removed with any acetate, ketone, or ester solvent. The uncured sealant can be removed by wiping with any standard hydrocarbon solvent.

Specifications Table

Shelf Life
Aerosol: 2 years
Bottled (unopened or opened & resealed): 2 years
Weight Loss
@50°C for 175 hours (Grams/cm2): 5 x 10-6
Max. Leak Size
(that can be sealed)
2 x 103 (T-L/sec)
2.6 x 103 mbar-L/sec
Ave. Curing Times
Room Temp: 24 hours
230°C: 75-90 min.
250°C: 60-70 min.
400°C: 20-30 min.
Compatible with
Ultimate Pressures of
1 x 10-12 Torr
1.3 x 10-12 mbar
Temp. Extremes
-200 to 450 (°C)
Product Downloads
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Fluids FAQ
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Ordering Table

All dimensions listed below, unless otherwise stated, are in grams.

Description Grade Size Safety Data Sheet Part Number Price In Stock Add To Cart
Description Grade Size Safety Data Sheet Part Number Price In Stock Add To Cart
VACSEAL LEAK SEALANT, 16 OZ AEROSOL, *HAZARDOUS MATERIAL SPECIAL SHIPPING REQUIRED* Vacseal 16 oz. Aerosol Can Please contact us for the SDS for this product VACSEAL-16A $172.00 In Stock
VACSEAL LEAK SEALANT, 2 FLUID OZ BTL Vacseal 2 fluid oz. SDS for VACSEAL-2B VACSEAL-2B $140.00 In Stock
VACSEAL LEAK SEALANT, 0.5 FLUID OZ BTL Vacseal 0.5 oz SDS for VACSEAL-0.5B VACSEAL-0.5B $60.00 Contact KJLC for Availability
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