Flamemaster Chemseal B2 Tank Sealant CS3204

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Kit 1 (2.5 oz. sealant) Kit 2 (6 oz. sealant/ 3.5 oz fill) Kit 3 (Pint sealant)Kit 4 (Quart 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)

Kit 4: Quart

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
California Prop 65 Warning Symbol

WARNING: Cancer and Reproductive Harm -

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I got the Kit 1, with 2.5oz of B2 sealant, labeled NSL brand. While I was dreading the project of fixing my fuel leak, this stuff is actually not bad to work with. It doesnt have a strong smell, and the mess is very manageable if you leave the back cap on and use the included applicator tip. Any excess sealant on the aircraft can easily be wiped away with acetone prior to full cure after that, use Poly Gone. Theres no need for a caulking gun or the sealant mixer tool that goes on a power drill. When freshly mixed, you can squeeze this out with just thumb pressure on the back. When you cant reach any further, push with a deep socket. Throughout the 2hr application time, the sealant will get harder, so if you think youll need that full time, squeeze it out into a paper cup and use popsicle sticks instead.

Kenneth J
November 17, 2023

Product was as good as we used at Bombardier aerospace

Richard C Verified Purchase


October 24, 2023

Product is as good as we use at Bombardier aerospace

Richard C Verified Purchase


October 24, 2023

awesome stuff

Rich P Verified Purchase


October 21, 2023

Dang, this stuff is easy to use,,, and works well in any caulk gun.

Rich P
October 12, 2023

Waterloo F Verified Purchase


October 10, 2023

The tubes make sealing large areas a lot faster. Not having done many tanks, I can lay a bead, smooth it out and assemble the parts much faster using the tubes than batch mixes.

Marty T Verified Purchase


July 15, 2023

It still has that pleasant odor and smooth, creamy taste. just kidding! If you have a large job to do, get the tube. It works great for sealing stringers and ribs because you can apply and spread it out quicker. When the pot life clock is running, its best to have a way to do things quicker.

Marty T Verified Purchase


June 29, 2023

Did the trick, seals as described, nozzle included

Jeffrey F Verified Purchase


June 20, 2023

We used 8802 at Lockheed for structural assembly and I was looking for some for building race cars and this is it. It is just as smelly, goooyie, messy, and strong as 8802. Industrial grade.

Neil C Verified Purchase


June 9, 2023


Please note, Aircraft Spruce'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 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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