Sealant is the best option if you are looking to permanently waterproof wood surfaces. You will need to completely saturate the wood with the sealant and build up the product until it forms a hard shell.
Sealant. Sealant is a popular choice for waterproofing wood, offering long-lasting protection by forming a waterproof barrier on the wood's surface. Sealant is one of the closest options for how to permanently waterproof wood. Unlike oil, sealants provide both strength and protection.
The best finish for wood in a humid, damp environment is a high-quality polyurethane or a marine-grade varnish. These finishes provide a durable, water-resistant layer that helps prevent moisture from penetrating the wood. Regular maintenance and reapplication may be necessary to maintain protection.
Applying a wood oil fills these holes and in doing so, keeps the wood supple and waterproof. Once exposed to Oxygen, these oils oxidise and harden in the surface of the wood grain to become part of the wood. The finish they provide is dry (non-greasy), and to varying degrees, moisture, stain and dirt resistant.
Varnish and paint are the two most practical options since they are easily applied with a sprayer or paint roller that can reach the top of these often-tall structures. It's best to apply penetrating oil to the wood before it's assembled into the finished piece since you must apply the oil with a brush.
The most affordable way to waterproof wood is by starting with a natural wood oil and following with a coat or two of outdoor paint. Though more budget friendly in the short term, you will need to redo this method more frequently, as it is not as long lasting as, say, a pricier, high-quality sealant.
How do you keep untreated wood from rotting? Treat it with outdoor wood preserver to protect it from biological growth that causes wood rot.
Is Polyurethane Waterproof? This finish protects your floors, but polyurethane is not waterproof. It will make your floors water-resistant, though — the coating repels water and helps prevent water absorption.
Untreated wood is the most susceptible to rot, fungi, and general weathering. It's extremely important that you use a wood preservative first. You can either use a wax enriched preservative for an all-round coating or alternatively use a wax-free preserver if you want to then use a stain or a paint on top.
If wood fibres were to absorb moisture and stay damp, they would become the perfect meal for wood rot bacteria. Especially since bacteria love to feed on the proteins found inside natural solid wood. So, by preventing water-absorption, oiling wood helps to prevent rot.
Many woodworkers choose polyurethane as a go-to finish simply for its familiarity. Easy to apply, it looks good on a variety of woods and provides plenty of protection.
There are three surefire ways to waterproof your wood for years to come. Use linseed or Tung oil to create a beautiful and protective hand-rubbed finish. Seal the wood with a coating of polyurethane, varnish, or lacquer. Finish and waterproof wood simultaneously with a stain-sealant combo.
Do I need to apply a clear waterproofer over my stain? Not with Thompson's® WaterSeal® Wood Sealers. They are specially formulated so you get unsurpassed waterproofing protection and beautiful color at the same time.
Thompson's Water Seal
Thompson's has been a trusted brand for wood and concrete waterproofing products for decades. This is why in most woodworking blogs, their water seal always tops the list of recommended wood sealers. Aside from resisting most types of mold and mildew, it's also long-lasting.
With proper upkeep and maintenance, you can extend your furniture's lifespan for years beyond what wood could handle on its own. Another benefit is that polyurethane keeps moisture away from wooden surfaces to prevent rot.
Waterproofing your wood for indoor use
If you're looking to seal some wood internally, a wood oil will do a good job. Products containing danish, linseed, teak and tung oil are popular choices for a beautiful, waterproofed finish.
Spar varnish is a great topcoat for outdoor and raw wood projects, especially if they are going to be in contact with water and in full sunlight. It's marine-rated, so you can trust that it will help your indoor wood furniture hold up to unexpected outdoor weather.
Untreated wood doesn't share the durability as pressure-treated lumber, because it lacks the same protective chemical preservatives. When left unprotected against elements like rain or snow, this type of wood deteriorates quickly – often within just a few years.
Used engine oil, like any other oil, is hydrophobic, while allowing additional protection of wood from water and moisture. Spent engine oil impregnation significantly reduced water and moisture absorption properties of wood.
One evenly spread coat will make your furniture water resistant. Most furniture builders, however, will put on three coats, with a very light sanding using 0000 grit steel wool, then using a tack cloth to remove any dust before applying next coat.
The short answer is yes, to a certain degree. There are several factors that make some polyurethanes more absorbent than others. Depending on the physical properties and material, thermoset polyurethanes can practically have zero water absorption compared to other known materials.
Is Linseed Oil Waterproof? Linseed oil is inherently water repellant (hydrophobic). However, when used as a wood finish, linseed oil can be susceptible to water damage. Try to avoid putting cold glasses on oiled furniture without coasters, and if the oiled surface does get wet, wipe it dry as soon as possible.
Sealing outdoor wood can be accomplished using a variety of products, including Osmo UV Protection Oil and Owatrol Textrol. Osmo UV Protection Oil is a clear finish for exterior wood that provides excellent protection against the sun.
Cuprinol Wood Preserver is the best clear deck sealer out there, designed for application on pressure treated wood and for both exterior and interior types of wood. Apply this preserver before painting, staining or varnishing your deck to protect against decay, rot and mold.