In general, there are two types of finishes, film-formers and penetrating oils. Film-forming finishes tend to dry into clear, hard films regardless of the substrate that they are applied. Penetrating oils tend to dry slowly and into soft, cloudy films when applied to a non-porous surface (like glass) and work best when they can penetrate into the substrate (hence the name). For more discussion on and examples of different types of finishes, see our Types of Finishes discussion.
There are a wide variety of wood coatings available and many of them can be mixed and matched to get a desired look, feel or level of protection. Waterlox alone provides multiple product lines that can be combined in a variety of ways to achieve your desired outcome. The key is to understand what type of coatings you are dealing with and knowing the possible issues. With proper information and testing, you can be sure to achieve a good, long lasting finish.
Your Waterlox Product
Waterlox produces both film-forming and penetrating oil finishes. For more information about what your Waterlox product is, please see our What are Waterlox Finishes discussion.
Film-Forming
Penetrating
Can this Waterlox product be used over my existing finish?
The short answer is maybe. Certain combinations will work very well and can be quite common; however, it is important to note that there is no guarantee when combining products from different manufacturers. It is ALWAYS recommended to test your full finishing system on a scrap piece of material or in an inconspicuous area to ensure good results of your project. See the Potential Problems section in the Types of Finishes guide for more information on mixing finishes.
My existing finish is a film-forming finish
If you would like to put a Waterlox product over your existing film-forming finish, it is highly recommended to completely removed and strip to bare wood.
Waterlox finishing systems are designed to penetrate and anchor down into the wood. The presence of a film on the surface will either completely prevent, or severely inhibit the Waterlox to function as intended.
The two caveats would be paint or “thinned down” film-formers. Waterlox film-forming finishes can be used over some paints, but testing should be done before hand to ensure compatibility and appearance. See our Decorative Finishes and Waterlox guide for more information. Thinned down film-forming finishes are somewhat common. Some examples would be thin cuts of dewaxed shellac or very low solids urethanes used as pre-stain wood conditioners or sealers. These will never be standalone products, so you can always check the instructions to see if additional products to complete the finishing system.
My existing finish is a penetrating finish
If your existing finish is more of a preparation step, then all Waterlox products can potentially be used over it with good results. This would include pre-stain conditioners or penetrating stains (see Stain and Waterlox for more information).
If your existing finish was intended to be the final finish, you may need to alter your Waterlox process to achieve good results. Some examples would be Danish oil, butcher block oil, pure tung oil, boiled linseed oil, hardwax oils, butcher block conditioner, mineral oil, etc.
- Most Waterlox finishing systems will start with some form of a penetrating product; therefore, the existence of an existing penetrating finish will be in the way. If you intend to use the Universal Tung Oil Sealer or a TrueTone color, the existing finish should be completely removed and stripped to bare wood.
- If the existing finish contains wax (e.g. butcher block conditioner, hardwax oils) or if it was waxed, the wax needs to be removed as best as possible before using any Waterlox products.
- If the surface is well sealed with your existing coating, but increased protection or gloss is desired, you may be able to apply a Waterlox film-forming finish over top of what you have.
- The existing finish should be very well dried and cured. A healthy wipe with paint thinner or mineral spirits should help to remove any residual uncured oils.
- The complete system should be tested on a scrap piece or inconspicuous area to ensure good chemical compatibility, adhesion and desired final appearance and color.
