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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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B2 is a little slow to cure in cool wearing but the longer working life really lowers the stress level if you have a lot of fasteners or rivets to get in before it sets up.

Wayne ( Verified Purchase

CHEMSEAL B2 3 1/2 OZ CS3204

November 19, 2021

Aveox, I Verified Purchase

CHEMSEAL B2 3 1/2 OZ CS3204

November 4, 2021

Perfect amount for a small job. 2 hr work life assures time to do the job neatly.

David L Verified Purchase


October 5, 2021

Glenn J Verified Purchase


September 14, 2021

Good service

Duane D Verified Purchase


August 4, 2021

Easy to mix and use. Follow directions on package. A Little stiff on application for smoothing with a paint brush. Very good!

Steven J Verified Purchase

CHEMSEAL B2 3 1/2 OZ CS3204

August 1, 2021

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


Please note, Aircraft Spruce Canada's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce Canada assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

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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