Wood stain is not flammable after it dries. The solvent in wood stain is what causes the liquid form to be highly flammable, but the stain drying process involves the solvents dissolving, which leaves behind a non-flammable product on your wood project. Wood stain is, however, flammable before you apply it, so you should always store partially full cans and used wood stain rags away from sources of heat and open flames.

There’s no single paint that’s the most waterproof. Instead, there are several types of waterproof and water-resistant paints that suit different purposes. Epoxy paint, for instance, is commonly used to provide a waterproof coating to floors and decks. Masonry paint is an excellent choice for exterior walls. Meanwhile, there are waterproof acrylic paints that can be used for interior and exterior walls. It’s more about choosing the best type for what you’re painting instead of the most waterproof paint overall.

The longevity of paint on wood depends on factors like the quality of the paint, surface preparation, exposure to elements, and maintenance. Exterior paint on wood surfaces can last 5 to 15 years or more with proper care and maintenance. Interior paint tends to have a longer life span, often 10 years or more. Regular cleaning, touch-ups, and addressing any issues like peeling or cracking can extend the life of the paint. 

Limewash and whitewash are two techniques used to give brick a light, matte finish, but they differ in composition, application, and permanence. The best choice depends on your aesthetic goals and the specific surface.

Composition

• Limewash: A natural and environmentally friendly option made from limestone, water, and sometimes pigments. It is breathable and soaks into porous surfaces like brick.

• Whitewash: Traditionally made from lime, water, chalk, and binders, but a similar look can be achieved with watered-down white paint. It is paint-based and sits on top of the surface.

Appearance and Finish

• Limewash: Provides a natural, textured appearance that allows the brick's character to show through. It offers a more traditional finish.

• Whitewash: Creates a softer, more opaque finish, often used for a rustic or shabby-chic style.

Application and Permanence

• Limewash: Is semi-permanent and can be removed, making it a good choice if you might want to change the look in the future. It requires more skill to apply and cannot be used on previously painted brick.

• Whitewash: Is a more permanent solution. It is more forgiving to apply and can be used on painted brick. However, because it sits on the surface, it can trap moisture.

Ultimately, if you want a breathable, natural, and reversible finish for unpainted brick, limewash is a great option. If you need a more permanent, opaque coating that can be applied over painted surfaces, whitewash is the better choice. Whitewashing may also be more economical, costing approximately $1.40 to $4.20 per square foot.