This is a general reference guide for using Waterlox products in conjunction with other types of finishes. There are always some exceptions and proper testing should always be done when combining different brands and types of finishes. See the “Mixing and Matching” section in the Types of Finishes guide for more information about testing for compatibility.
Waterlox Finishes
Film-Forming
Penetrating
Using Waterlox with Other Common Finishes
Urethanes (Water or oil based)
Type of Finish: Film-Forming
Over Urethane
No Waterlox products should be used over urethanes. They should be completely removed before using Waterlox.
Under Urethane
All Waterlox products can potentially be used under other urethanes. Proper testing is required for compatibility and adhesion.
Shellac
Type of Finish: Film-Forming, but thin cuts can be used similar to a penetrating finish.
Over Shellac
Most Waterlox products can be used over dewaxed shellac. Thin cuts of dewaxed shellac used to seal oily woods should work fine under all products. Penetrating Waterlox products should not be used over thicker coats of shellac. Waxed shellacs should be removed completely as the wax may cause adhesion issues.
Under Shellac
Waterlox products should not be used under shellac. The alcohol used as the solvent for shellac can attack the coats of Waterlox underneath and may lead to soft, weak films.
Lacquer
Type of Finish: Film-Forming
Over Lacquer
Waterlox film-forming products can potentially be used over lacquer, but it is not ideal as the Waterlox cannot penetrate. Also, the solvents in Waterlox products may soften or damage the lacquer, so proper testing should be done. Ideally, it should be completely removed.
Under Lacquer
Lacquer should not be used over any Waterlox products. Lacquer thinner will most likely soften or damage the Waterlox products.
Mineral Oil
Type of Finish: Penetrating
Over Mineral Oil
Waterlox products can be applied over mineral oil as long as it is very dry. Wait at least 2 weeks after the last application of mineral oil. Wipe down the surface with a healthy amount of mineral spirits or paint thinner to help remove any residual mineral oil. Allow the surface to dry for a few hours or overnight before coating.
Under Mineral Oil
Mineral oil should not be used over any Waterlox products. They will not be able to soak into the wood, so they will leave an oily residue on the surface.
Drying Oils – Linseed, Boiled/Bodied Linseed, Tung Oil, Walnut, Teak Oil
Type of Finish: Penetrating
Over Drying Oils
Waterlox film-forming products should be compatible with most drying oils as long as they are thoroughly dry. It is recommended to allow a minimum of 2 weeks before topcoating. Some forms of oil (bodied/polymerized) may cure faster than others. Test before continuing. A coat of Universal Tung Oil Sealer may or may not be required depending on how saturated the wood is.
Waterlox penetrating finishes will generally not work well over other drying oils as the wood is already saturated. If the current finish is older and starved, you should be able to use Waterlox penetrating finishes to restore the current finish.
Under Drying Oils
Other drying oils should not be used over any Waterlox products.
Wax or Hardwax Oils (Rubio Monocoat, Osmo Poly-X, Fiddes, etc.)
Type of Finish: Penetrating. Wax alone (paste waxes) doesn’t actually penetrate, but it does not form a solid continuous film, so it is not a film-forming finish. Hardwax oils and Butcher Block Conditioner products are a blend of drying oils and waxes.
Over Wax and Wax Containing Products
See Wax and Waterlox.
Under Wax and Wax Containing Products
See Wax and Waterlox. Waterlox products should not be used under hardwax oils or other similar products. These are essentially Drying Oils (see above) and the same rules apply.
Varnish (Spar, Moisture Cure, Conversion, etc.)
Type of Finish: Film-Forming
Over Varnish
Waterlox film-forming products can potentially be used over other varnishes, but it is not recommended. The Waterlox products will not be able to penetrate as designed (see Urethanes).
Under Varnish
Waterlox products may be able to be used under other types of varnish. If using specialty varnishes (moisture cure, 2K, acid cure, conversion, etc.) ensure that the reactive chemistry will not harm the Waterlox underneath.
Danish Oil
Type of Finish: Penetrating
Over Danish Oil
Danish oil is usually described as a mix of oil, varnish and solvent. Essentially it is a drying oil with a small amount of resin (the varnish) added to help drying and build. Treat it the same as the drying oil section (above).
Under Danish Oil
You could potentially use Danish oil over Waterlox penetrating finishes, but it is not recommended.
Prefinished – Specifically Aluminum Oxide
Type of Finish: Film-Forming
Over Aluminum Oxide
Aluminum oxide coatings are extremely hard and have a very unique chemistry. No Waterlox products should be used over an aluminum oxide finish. It should be completely removed which can be very difficult. Consult a professional.
Under Aluminum Oxide
Aluminum oxide coatings are applied at a factory due to the complicated process and equipment needed. This should never be an option for site-applied finishes.
Stain and Pre-Stain Conditioners
See Stain and Waterlox.
Additional Guides
