---
product_id: 41959850
title: "Red Devil F Seal 181 Water Based Duct Sealant"
brand: "red devil"
price: "$214.41"
currency: USD
in_stock: true
reviews_count: 13
category: "Red Devil"
url: https://www.desertcart.ec/products/41959850-red-devil-f-seal-181-water-based-duct-sealant
store_origin: EC
region: Ecuador
---

# Fiber-reinforced leak-proof seal Weather-resistant durability UL 181 A-M & B-M certified Red Devil F Seal 181 Water Based Duct Sealant

**Brand:** red devil
**Price:** $214.41
**Availability:** ✅ In Stock

## Summary

> 🔧 Seal smarter, save energy, and join the HVAC elite!

## Quick Answers

- **What is this?** Red Devil F Seal 181 Water Based Duct Sealant by red devil
- **How much does it cost?** $214.41 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ec](https://www.desertcart.ec/products/41959850-red-devil-f-seal-181-water-based-duct-sealant)

## Best For

- red devil enthusiasts

## Why This Product

- Trusted red devil brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Seal Like a Pro:** Fiber-reinforced formula guarantees airtight HVAC performance, slashing energy waste.
- • **Certified Confidence:** UL 181 A-M & B-M certification means trusted compatibility with all duct types—metal, fiberglass, and flexible.
- • **Fast & Safe Application:** Low VOC, quick-drying formula ensures a clean, eco-conscious seal with minimal downtime.
- • **Exceeds Industry Standards:** Surpasses SMACNA Pressure and Sealing Classes for top-tier HVAC system efficiency.
- • **Built to Brave the Elements:** Weather-resistant and mold-proof for reliable indoor/outdoor use, no matter the climate.

## Overview

The Red Devil 0841DX F-Seal 181 is a premium, fiber-reinforced, water-based duct sealant designed for superior HVAC sealing. UL 181 A-M & B-M certified, it works seamlessly on metal, fiberglass, and flexible ducts. Its fast-drying, low VOC formula ensures safe, efficient application indoors or outdoors, while exceeding SMACNA standards for pressure and sealing. Weather-resistant and mold-proof, this USA-made sealant enhances energy efficiency and system longevity.

## Description

Red Devil F-Seal 181 is a premium fiber-reinforced water-based duct sealant engineered for superior performance in all HVAC systems. This versatile sealant is UL 181 A-M & B-M certified, making it suitable for metal, fiberglass, and flexible ducts. Its fast-drying, low VOC formula ensures quick application and safety in sensitive environments. F-Seal 181 exceeds all SMACNA Pressure and Sealing Classes, providing unmatched sealing capabilities for high, medium, and low-pressure HVAC systems. The durable, weather-resistant formula is perfect for both indoor and outdoor use, resisting mold, mildew, and UV damage. It contributes to LEED EQ Credit 4.1 and meets CA Dept. of Public Health Emission Requirements V1.1, 2011. This USA-made product offers excellent adhesion, flexibility, and can be painted after full cure. For best results, apply in temperatures between 40°F and 110°F, allowing 24-72 hours drying time before pressure testing. F-Seal 181 is your go-to solution for efficient, long-lasting HVAC duct sealing.

Review: Excellent Duct Sealant – Noticeable Improvement - I used Red Devil F-Seal 181 to seal the joints and seams on my HVAC ductwork, and I'm very impressed with the results. It was easy to apply, spread smoothly, and dried into a durable, flexible seal. After sealing the ducts, I checked the surface temperatures with an infrared thermometer. The photos show the difference—one section measured about 78°F, while the sealed insulated duct measured around 69°F. That gave me confidence that sealing the leaks helped reduce air loss and improved the system's efficiency. A little goes a long way, it cleans up easily while it's still wet, and once cured it forms a tough seal. If you're looking to improve your HVAC system and stop air leaks, I highly recommend this product. Made in the USA is an added bonus
Review: Great for sealing leaks and stopping drafts - Fantastic. Worked great for sealing the ducts and ceiling vents in my home. My home is newer built but for some reason they didn't seal around the ceiling vents from the attic. The home was very drafty and leaking air conditioning. It solved the problem. It's very thick and goes on easy with a brush. Drying time is surprisingly quick but it should take 24 hours to fully cure.

## Features

- SUPERIOR SEALING: Fiber-reinforced formula ensures leak-free HVAC systems, improving energy efficiency and performance
- VERSATILE APPLICATION: UL 181 A-M & B-M certified for use on all types of HVAC ductwork, including metal, fiberglass, and flexible ducts
- INDOOR/OUTDOOR DURABILITY: Weather-resistant sealant withstands various conditions, making it ideal for both interior and exterior use
- FAST-DRYING & LOW VOC: Quick application and reduced drying time, with low volatile organic compounds for safer use in sensitive environments
- EXCEEDS INDUSTRY STANDARDS: Surpasses all SMACNA Pressure and Sealing Classes, ensuring top-quality performance for your HVAC systems

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B01I7JVUO0 |
| Best Sellers Rank | #10,976 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #46 in Hardware Sealers |
| Brand | Red Devil |
| Brand Name | Red Devil |
| Color | Gray |
| Compatible Material | Fiberglass, Metal, Plastic |
| Customer Reviews | 4.5 out of 5 stars 1,529 Reviews |
| Global Trade Identification Number | 00075339003466 |
| Included Components | Duct Sealant |
| Item Dimensions | 7 x 7 x 8 inches |
| Item Form | Paste |
| Item Type Name | Water Based Duct Sealant, 1 Gallon |
| Item Weight | 16 ounces |
| Item dimensions L x W x H | 7 x 7 x 8 inches |
| Manufacturer | Red Devil |
| Material | Acrylic |
| Material Type | Acrylic |
| Model | 0841DX |
| Number of Items | 1 |
| Part Number | 0841DX |
| Style | 1 - Pack |
| Style Name | 1 - Pack |
| Supported Standards | UL 181 a-m, UL 181 b-m |
| Surface Recommendation | Metal |
| UPC | 075339003466 |
| Unit Count | 128 Fluid Ounces |
| Water Resistance Level | Water Resistant |

## Product Details

- **Brand:** Red Devil
- **Item Weight:** 16 ounces
- **Item dimensions L x W x H:** 7 x 7 x 8 inches
- **Material:** Acrylic
- **Style:** 1 - Pack

## Images

![Red Devil F Seal 181 Water Based Duct Sealant - Image 1](https://m.media-amazon.com/images/I/718Qkc+7HiL.jpg)

## Available Options

This product comes in different **Color, Size, Style** options.

## Questions & Answers

**Q: Is the "F" in the bucket like a liquid (brushable) or more like a paste?**
A: It's not quite like a paste but it's not liquidity either and doesn't drip so you can put it on thick.  I love this stuff, not much of a odor as well. I used a cheap chip brush to spread it.

**Q: I'm redoing all the flex ductwork (insulated kind) in a crawl space. should i use the d our f sealant ?**
A: You could use either one.  Both are perfect for what you are doing, but I would use the F-Seal because it has fibers in it.

**Q: Is this safe to use and will it work on gas dryer duct work joints (inside the fittings and outside)?**
A: Sorry, this should not be used on a dryer. It is for HVAC only. Thanks.

**Q: How long do I need to wait before turning on the A/C after application?**
A: Hi, you should wait 24 hours. Thanks....

## Customer Reviews

### ⭐⭐⭐⭐⭐ Excellent Duct Sealant – Noticeable Improvement
*by J***. on July 22, 2026*

I used Red Devil F-Seal 181 to seal the joints and seams on my HVAC ductwork, and I'm very impressed with the results. It was easy to apply, spread smoothly, and dried into a durable, flexible seal. After sealing the ducts, I checked the surface temperatures with an infrared thermometer. The photos show the difference—one section measured about 78°F, while the sealed insulated duct measured around 69°F. That gave me confidence that sealing the leaks helped reduce air loss and improved the system's efficiency. A little goes a long way, it cleans up easily while it's still wet, and once cured it forms a tough seal. If you're looking to improve your HVAC system and stop air leaks, I highly recommend this product. Made in the USA is an added bonus

### ⭐⭐⭐⭐⭐ Great for sealing leaks and stopping drafts
*by S***P on June 5, 2026*

Fantastic. Worked great for sealing the ducts and ceiling vents in my home. My home is newer built but for some reason they didn't seal around the ceiling vents from the attic. The home was very drafty and leaking air conditioning. It solved the problem. It's very thick and goes on easy with a brush. Drying time is surprisingly quick but it should take 24 hours to fully cure.

### ⭐⭐⭐⭐⭐ Worked great for me
*by O***D on April 28, 2025*

Background, my attic was a horror show. Duct insulation that had been pinned on with 4" nails by some insane attic seamstress. Vents were uninsulated. Bare ductwork metal in too many places to count. I could go on at length, but you'll have to wait for the book. Bucket arrived in good shape. Shipping was good, then it was delayed, then it was delivered. Some of the other items in the box had a little mastic on them but the bucket I got looked pristine, unleaked, and had 2 lengths of sturdy tape holding the lid on. Mastic inside was not dried or disturbed. I have to wonder if their initial try showed the folly of shipping buckets rattling around in a box. But I digress! Simply put my order of grey goop arrived in great shape. I had ordered a box of 10 or 12 cheap 'chip' brushes so I could use one for the day and just ditch it. I would tear off old poorly applied duct insulation, mastic all seams and screws of the ductwork on my list for the day, and retreat to places more hospitable to humans until the next day. I would leave the bucket fully resealed in the attic: the handle came off on day one and I couldn't get it back on. Easier to leave it where I'm going to use it next rather than lugging it back and forth. It's springtime in Texas, I have a remote thermometer in the attic, and it hit 140° up there the other day. So yeah, I just let it dry till the sun comes up again, then use duct wrap and sleeves with high quality tape. In my attic that's as dry as it's ever going to be. The temperature had no effect on the mastic still sealed in the bucket. Spreads well, seals well, dries well. I intend to eventually go back deep in the attic and mastic at least the edges of all my tape, working my way back to civilization and the attic stairs. I trust the mastic to secure the tape more than I trust the tape not to curl over the years. I wear cheap painter's coveralls and surgical gloves as the mastic, and everything else, tends to get quite snuggly with me. My roof comes down to the soffit on all sides so I'm an old man crawling across the joists and some places can sit up. I still come down looking like a coal miner after a double shift but at least most of the mastic is on the ductwork instead of me. It's brutal up there, so I pick my work for the day, let the mastic start drying, and get out while I still can. Oh yes, don't let the AC or heat come on while your mastic is still drying. Don't want to take a chance on displacing the mastic after all your hard work. I have a little over a month until my youngest son visits and we blow in insulation. I'm going to bury everything up there to the extent I won't be able to get in there to do anything. So, everything I'm going to fix had better be done before then. I'm trusting this mastic to last half of forever because I'm going to make it all but inaccessible in June (God help me). My end game is to stop making the electric company rich, and never go in the attic again.

## Frequently Bought Together

- Red Devil 0841DX F-Seal 181 Fiber Reinforced Water Based Duct Sealant, 1 Gallon, Gray, Made in USA
- Pro Grade - Chip Paint Brushes - 12 Ea 2 Inch Chip Paint Brush Light Brown

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*Product available on Desertcart Ecuador*
*Store origin: EC*
*Last updated: 2026-08-13*