Gray 1 Gallon Red Devil 0841DX F-Seal 181 Fiber Reinforced Water Based Duct Sealant

Strobble: I had a couple of holes where the main furnace joined to the coil box. I used this to seal them. My furnace is installed vertically and the builder mastic'd everywhere so when I clean the coils next year, this product should do the trick when closing it back up. I used my fingers with doctors gloves on to apply it. Simple.

United States on Oct 25, 2023

Reid terry: Sealed up pretty big gaps in my duct work.

United States on Oct 11, 2023

Michael Orzel: Very pleased with performance. By sealing the gaps I could find around the furnace room (not a whole system tear down) I improved airflow at the registers by approximately 40%. Anemometer verified!

United States on Oct 03, 2023

Amazon Customer: The bucket came well moistened, not dried out at all!
Use your throw away brush and smear it on. Hardens like a rock.

Canada on Aug 09, 2023

Andy M,: All the duct seal products are too expensive but this is a little cheaper and works as well or better than other brands I've tried. Seems like it goes on easier and covers better; this doesn't shrink as much so if you're using mesh tape under it, you won't need a second coat.

United States on Jun 06, 2023

Meeikal: It works well, easy to apply with a brush or gloved hand. It dries lighter in color which blends decently with existing ducting. It seemed to improved the air flow in my hvac system quite a bit. I’m going to go over the system again because I now can see and feel where I missed as the air flow is so much more noticeable from leaks. It’s not a fun task but I appreciate the comfort having a tighter hvac system gives me. I have a older home from the 1960’s and my hvac is about 15 years old.

Amazon packed this sideways for unknown reasons and the product leaked inside the box. It wasn’t bad but I would by this from a hardware store next time.

United States on Apr 26, 2023

Thierry Henri: I am still observing how good this product is.

Canada on Jan 31, 2023

zsikli: I didn't use fiberglass mesh but shouldn't be an issue to do so. Goes on easily. Dries quickly. This stuff is not ruined if frozen. May be overkill but painted inside and out on a short run. Airtight!

Canada on Jan 08, 2023

Bernard v christin: I used this product in combination with the foil tape and the drywall mesh tape.
It's a sloppy job. I applied it with my hand wearing rubber gloves to protect against cuts. It's way faster than trying to 'paint' the seams, just take a dollop of grey goo and spread it with your hands.

Why isn't it sold in Canada, I do not understand....
All duct works should be covered in this stuff.
I almost used a full bucket for a 3000sq ft house and I covered all the joints and the vertical seams.
I have a 2 zone system but the returns are not ducted.
My product arrived in a bag inside a box and was not dry.
I am a happy camper

Canada on Jul 12, 2021

GB: I purchased this mastic in order to seal all of the joints in my heating and return ducts that were accessible in my basement ceiling.

It was exceptionally easy to apply…much like spreading toothpaste with a paint brush. It goes a long way! The mastic did not have an odor, and it dried very quickly after application. This job took me a few days to complete, and I used a new brush each day. I also put a layer of plastic wrap on top of the mastic before closing the lid with a rubber mallet each day, and this kept the mastic from drying out.

Because the majority of the duct work in my basement is up in the ceiling between the joists, and close to the plywood of the flooring above, I adapted some cheap 2-inch paint brushes so that I could actually brush the mastic on top of the joints. I bought cheap paint brushes that have wooden handles, and I trimmed the bristles quite short. Then, I cut off about half the length of the wooden handles with a hacksaw, which made little “stubbie” brushes. These shorter brushes allowed me to apply the mastic at the top of the duct work, and they made the application easier and more affordable.

I do recommend that you wash...

Canada on Mar 11, 2021