A breathable coating is defined as a coating that allows for small amounts of moisture to pass through it. Breathable coatings are often used on exterior applications, and in applications where moisture is a known issue but mitigation is not required.
The most common type of breathable coating is an acrylic coating. Not all acrylic coatings are breathable, most of them are. Under the category of acrylic coatings, there are a few different types of acrylics, each designed for different applications:
Armor AR350 and Armor AR500: The Armor AR350 and Armor AR500 are pure acrylic lacquers. They function differently from a traditional acrylic in that they are designed to leave behind a more durable wear surface. The Armor AR350 will give the concrete the appearance of being "wet" and will leave behind an attractive satin sheen; the Armor AR500 will slightly enhance the natural coloring while adding an attractive high gloss finish. The resins used in the AR350 and AR500 are high quality - they are designed to outlast and outperform traditional acrylics.
Armor AX25: The Armor AX25 is a Siloxane infused Acrylic. This unique type of acrylic offers superior water repellency characteristics making it the perfect sealer for pool decks. It is resistant to all types of water including fresh and rain water, salt water, and chloring water.
Armor LV25 and WB25: The Armor LV25 and Armor WB25 are acrylic co-polymer sealers that are also classified for use as a cure and seal (can be applied to new and green concrete). While the resins are comparable in quality, they are different from the ones used in the Armor AR350, Armor AR500, and Armor AX25.
Non-breathable coatings are not designed to allow moisture to pass through. The most common type of non-breathable coatings are epoxies and urethanes. Now, just because a coating is not breathable does not mean that it is resistant to moisture, and it doesn't mean that it will stop 100% of moisture. When non-breathable coatings are applied to moisture-saturated concrete, they may peel, flake, or fail. If you want to reduce moisture with a non-breathable coating, it needs to be approved for moist environments.
A common non-breathable coating is the Armor Epoxy. The Armor Epoxy is often used alone, or in combination with other types of urethane based coatings. The Armor Epoxy can reduce moisture from around 10 LBS to less than 3 LBS when properly applied. It won't stop 100% of moisture, but it will make a significant improvement without causing harm to the concrete.