Red Devil 0846DX F Seal 181 Water Based Duct Sealant, 10.1 Oz., Gray

I sealed my ducts in the basement and now my basement is not that cold anymore in the summer when my A/C is running. Now I know how much money I had wasted for the last 10 years :-). Now my upstair has more air flow and cooler.

I bought this to fill a small ducting leak in my a/c but also applied it to my house when doing stucco repairs on holes left behind by the last sprinkler timer on the outside of my house. It dried perfectly and painted over very well. I docked it a star because I noticed the canister developed a leak while dispensing the contents on the first use. I wasn't using much pressure with the caulk gun so not sure why it happened so easily. However, it did seal itself so I can continue using it. The packaging needs some improvement, though.

great buy great buy great buy

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 the joints of the duct work before applying the mastic so that the mastic adheres well. I actually washed all of the outer surfaces of my duct work before starting this job, and I was stunned at the 38-years of dirt and dust that I was able to wash off. I also wore disposable vinyl gloves when applying the mastic, as doing this job was quite messy. It was, however, easy for me to rub the dried mastic off of my skin with hot, soapy water. After the whole job was finished, my husband and I definitely noticed an improvement in the heat flow in our home. No more cold spots upstairs in the bedrooms, and no more hot spots in the basement due to leaky ducts. I hope we also notice a change when the air-conditioning is turned on this summer!

I'm not sure why this is impossible to find at DIY stores in Canada, but I will NEVER use tape again... if I can help it. This goes on like pancake batter and dries to a firm rubber consistency. If you embed fiberglass mesh tape in this mastic (I used fibaFuse mesh tape, found in the drywall section) this makes for incredibly strong and completely air-proof joints. It's messy as heck, but worth it!