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

Fast Delivery, shame the freight is so expensive.

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

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.

Great product, works as described

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.

Works well as expected.

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

Used sealant to repair obsolete 30 year old plastic fuel tank

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.

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.

Addition... Mixing: I clamped a slow speed drill (pointing up)in my vise and chucked a hole saw (backwards) that had holes that (nearly) matched the plunger handle of the tube. A couple of #8 screws, and I now had a power mixer. Turn on the drill (CW) and move the tube full stroke up and down 50 times (overkill) or so. Dispensing: Like a previous reviewer, I just used a cheap $5 gun.. mine didnt even require making the plunger diameter smaller.. it fit perfectly...

Used this (B-2)for sealing the fuel sending unit into the side of a wing tank. All is well. I would probably use the faster version next time (B-1/2). Cures very flexible, not as hard as Proseal, but it is a polysulfide product (like Proseal) so we will see how long it lasts.

Although I waste more than I probably should, I never have any issues with these kits not curing properly. I bought a cheap caulking gun and ground the ram down a bit on my bench grinder so that it fits the plunger on these tubes. Presto! $5 proseal gun! (use a zip tie to make sure the tube stays anchored in the cheap big-box store caulking gun)

This sealant works awesome. It cures to a hard rubber and really seals. After trying a different sealant and it not working, I was desperate to find something to seal up my fuel tank. This stuff fit the bill and is completely leak free.

...make sure the metal is bare and clean, i had a wing tank neck/nipple that i had to have a welder extended higher to work with my newly built wing tanks, after welding he gave a shot of spray paint on where he buffed the metal. After i threaded the nipple/neck into the top of the wing tank, I smeared the sealant on the inside of the nipple at the junction of the threads in addition to putting sealant on the fine threads. The sealant i had on the smooth part of the inside of the nipple started to lift because of the spray paint the welder put on after welding.

The brand I used says Flamemaster on the tube, which comes in a plastic bag. On the bag it says NSL Aerospace and shows a website www.nslaerospace.com the fuel fittings I used it on and even on my rubber dust cover where my wing tank fuel neck comes up through have all held out Excellent since I put it on last summer, and is still nice and flexible around my fuel neck nipple. I also used some to seal a rubber grommet on top of my white plastic football fuel tanks on my Ultralight and thats still Excellent.

I used it again with Excellent results, this time I was more aggressive with the mixing giving it more than the recomended min 50 strokes and like it says on the packaging extra mixing may initiate curing of sealant inside the cartridge...which it did, as I noticed it got hard to push it out of the cartridge ( I was just using my thumbs to push it out of the cartridge as I don't have the cartridge gun or know where they sell it ??) but I still had plenty of time to get what I needed out of the cartridge for my job on my new fuel tank...it works no leaks on the NTP threads !! Its too bad they don't make smaller tubes to eliminate waste, because once its mixed you must use it, as the stuff left inside the cartridge sets up to a rubber like solid compound within hrs or overnight.

You must not have mixed it properly I used it twice and it cured within 4 hrs to where I was forced to open a new tube cause it cured enough that when I need more it was set up in the tube after 4 hrs in hot weather.

I received two brands. One is Flame Master Chem Seal CS3204 from National Sealants & Lubricants and is excellent even after one year of storage it cures in one day at 28°C cures to a hard flexible rubber shining surface. The other brand was A-C-Tech AC-226 B4 from Advance Chemistry & Technology , and it didn't cure after 14 days just became less sticky.