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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 can (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
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Great stuff! I see it in my airline career and on my 172. This was for my sons boat but hey it seals aluminum and sticks.

Phillip P Verified Purchase

CHEMSEAL B2 3 1/2 OZ CS3204

July 14, 2021

Excellent product! I would order again!

Daryl A Verified Purchase


July 2, 2021

I bought two tubes. One worked properly the other one did not cure out. There was not enough hardener, in the mix, for it to set up properly.

Curtis I Verified Purchase

CHEMSEAL B2 3 1/2 OZ CS3204

June 24, 2021

I used this product to seal a leak between the aluminum fuel tank and mounting straps on my Freightliner semi truck. It has only been a week but there is no leaks and I believe this fix will last forever. Definitely cheaper than $2500 for a new tank. Ordering another pint for the other side.

Robert S Verified Purchase


June 4, 2021

The best sealant

Darrin B Verified Purchase


June 2, 2021

Nick C Verified Purchase


May 27, 2021

This is the perfect size for a tank leak repair. The mixing is almost automatic so you get a reliable cure. Ships fast and is worth the price.

Nicholas M
May 12, 2021

Worked great.. less mess.. easy to mix.. works in normal caulk gun as well! BONUS!

February 10, 2021

Highly recommend this product for sealing exterior pin holes on fuel bladders. Material can be applied on vertical surfaces and does not run or sag. Comfortable working time on previously prepared surfaces. Product has excellent surface bonding characteristics. Product appears to be resistant to ethanol blended fuels. Advise doubling recommended curing times

Alan Z
September 16, 2020

Fast Delivery, shame the freight is so expensive.

Geoff S
August 14, 2020


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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