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Kit 1 (2 oz. sealant)Kit 2 (3.5 oz. sealant)Kit 3 (16 oz. sealant)
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Kit 1: 2.5 oz cartridge (Fill: 2 oz. sealant)

Kit 2: 6 oz cartridge (Fill: 3.5 oz. sealant)

Kit 3: 6 oz cartridge (Fill: 16 oz. sealant)

CS3204 is a fuel resistant sealant for use on integral fuel tanks and pressurized cabins as well as other areas subject to contact with aircraft fuels, lubricants, oils, water and/or weathering.

At room temperature, this two-part polysulfide cures to a flexible, resilient rubber.

Meets requirements of specifications AMS-S-8802 formerly MIL-S-8802, CMNP021, Lockheed, Gulfstream, Hughes Aircraft, Fairchild SPS 6-1 & 6-2

Technical Data: Class B*
Cure Profile B-¼ B-½  B-1 B-2 B-4
Application Life (hrs) ¼  ½  2 4
Tack Free Time (hrs)  6 8 15 24 36
Cure Time (hrs) 16 30 40 72 90


Perfect for sealing our fuel tank fuel level float and attached fittings. Long work life as advertised

David L
July 7, 2020

Easy to mix without the use of special tools. I pushed the product out of the tube using a socket and extension as a pushrod. The Class B2 has a working time of 2 hours and a cure time (at 77 deg F and 50% RH) of 72 hours. Product worked as expected and seems to retain a little flexibility.

Leo K
May 20, 2020

Great product, works as described

Bens M
January 30, 2020

Convenient size for small jobs. Getting it between 70F and 80F before mixing makes the mixing very easy. The product can be pushed out with a thumb and does not require anything other than the packaging to mix and apply.

William W
January 25, 2020

Works well as expected.

John R
January 16, 2020

Had a leak in an integral aluminum fuel tank that hadnt been sealed properly since built. Worked superbly.

November 24, 2018

Used sealant to repair obsolete 30 year old plastic fuel tank

Neil C
September 14, 2018

Frank S
May 25, 2018

I really like this product. I use it at work on aircraft, and purchased it here to use at home on my airstream trailer renovation.

Joe S
April 6, 2018

Worked as advertised. Used the mixing tool in my drill and mixing was easy and fast. So far fuel tank is sealed up tight and nothing leaking. Hope it lasts for many years to come.

Terry B
March 16, 2018


Q: What is the maximum operating temperature of Pro-Seal after it has cured?

It has a service temperature range from -65*F (-54*C) to 250*F (121*C), with intermittent excursions up to 275*F (135*C).

Q: Is this Pro-Seal product compatible with methanol?

The tech data sheet only refers to aviation and jet fuel. It has been used in race vehicles that use many alcohol type additives without any known problems, but the supplier will not recommend it since it has not been lab tested.

Q: What is the shelf life of the unmixed product?

The shelf life is 9 months from date of packaging.

Q: Will Pro-Seal cure to a rigid state or will it remain flexible for repairs on a fuel bladder?

It will be flexible when cured, but we recommend verifying with the bladder manufacturer this material can be used.

Q: How do you mix this Pro-Seal tank sealant if you didn't purchase the mixing tool?

Per our product support manager: The user would have to pump and twist the ram manually by hand. The mixing tool saves a lot of time and effort.

Q: Does ethanol attack or dissolve Pro Seal over time?

Proseal has been used in ethanol applications, but the manufacturer has no documentation to provide to show how well, or how long, it will work.

Q: Will this Pro-Seal type tank sealant adhere to a plastic tank?

This will adhere to a plastic tank but will eventually breakdown because of the gasoline. This is mainly used for aluminum and titanium steel. This would not be recommended per supplier for a plastic tank.

Q: How do you dispense from these cartridges? Can they be used with a Semco gun and can you use a caulking gun like you would find commonly?

After the cartridge has been mixed, you can use a manual dispensing gun, p/n's 12-38520 or 12-38530, or an air-powered gun like 12-02923, 12-02922, 12-02921, or 12-02920. A Semco, or other common caulking gun is not designed to be used with these sealant cartridges.

Q: I only need to seal a small hole so I only need a small amount. Is this Pro-Seal Type Tank Sealant CS3204 similar to epoxy to mix and use?

It is self contained, and designed for a one time use. The two parts, A&B, are already properly measured, so the two parts are mixed in the cartridge until one uniform color and then you install the nozzle, and push rod, then just apply to the area.

Q: How much surface area will the 3.5 oz kit of Chemseal B2 sealant cover? I want to make sure I have enough product to seal my entire surface.

This will all depend on how thick you are applying this. However there is a formula that will help, if you apply this to an area that is 1" cubed so 1" length x 1" height x 1" depth, it would use exactly 1.8047 fluid oz.

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