Part# 09-04648
MFR Model# CS3204B1/2-QT


6 oz cartridge (Fill: 3.5 oz. sealant) or Quart size available

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 - www.P65Warnings.ca.gov.


Global S Verified Purchase


June 8, 2023

Now that I know they make a b4 sealant, now I can milk any maintenance project!!!!!!!! Thanks Chemseal!!!!!!!!!

April 4, 2022

Resealed a seep in my RV9A fuel tank--let it sit a week after applying the sealant before adding fuel--so far so good!

October 5, 2020

Ive used this to seal up EVAP leaks on a couple of cars. Bonds well to plastic fuel system parts. Saves the expense of having to pay for costly parts

Jackson C
July 27, 2020

Used it to successfully seal a fuel tank leak on my RV-8A. Seems to perform just like Proseal.

Lee E
June 24, 2020

Item was delivered on time and worked as expected. I would definitely use this vendor and product again.

June 24, 2020

This stuff is the best thing since sliced bread !! I used it to repair a fuel tank in a Bobcat skidsteer. the only way to get that tank out is to pull the engine out of the machine, so to avoid having todo that i used it to repair it which was still not easy but saved me countless hours of work, Ive been runniong the machine for days now after the repair and not a sign of a leak anywhere. now that Ive tryed this stuff I can think of many other things it would work great on. Its not cheap, But it is worth every penny I paid for it for the work it saved me.

Dale P
April 20, 2020

The sealant worked great for my application, however, the cure time I believe was more like 48 hours rather than 30 hours as in the spec. Im very happy with it though.

Steven S
March 12, 2020

I thought that I would try using this product since the price of Proseal is outrageous. I only needed to seal a few screws that’ were seeping slightly on one of my RV-8’s fuel tanks, so it was a small project. I’m happy to say that the Chemseal, at half the price of Proseal, did every bit as well. I’ll be purchasing Chemseal over Proseal in the future.

Roy M
March 5, 2020

In all fairness, I cannot rate this product since I have not used it as of this time. However, I am certain that it will meet or exceed my expectations. Presently, I am attempting to find a brass end cap fitting 3/8 inch with tapered NPT. Once I have found the fitting and sealed my fuel tank I will be able to use the sealant.

Lowell C
November 12, 2019


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: Does the quart size of this Chemseal sealant come in a can?

Yes, the quart size is in a can.

Q: What is the shelf life of Chemseal CS3204B1/2?

The storage life of CS 3204 is nine months when stored in the original unopened containers at temperatures below 80f.

Q: Where can I find the Safety Data Sheet (SDS) for this Chemseal B 1/2 sealant product?

We have added the MSDS PDF to the Documents section of this web page. Please review it there.

Q: What is the color?

These are an off white and when mixed they become a gray in color.

Q: does the B1/2 come in black?

We only offer it in off white.

Q: Does the pint size of the Flamemaster Chemseal Fuel Tank Sealant CS3204 B1/2 Gray come in a can?

Yes the pint size comes in a can.

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