All Waterlox coatings will cure through exposure to oxygen. Oxygen molecules seek out uncured sections of oil and undergo a chemical reaction that cross-links the oil and resin together to make a film. When a Waterlox coating is staying soft, tacky, or has a lingering odor, this is a sign that the oxygen is having a hard time curing all of the oil. Waterlox finishes will eventually cure as oxygen molecules slowly work themselves into the film to find any uncured bonds, but there are many ways to quickly speed up this process and greatly improve your final cure. If the coating was well cured initially and has gotten worse over time, then you are more likely dealing with an issue of improper maintenance and harmful cleaners. See the Care and Maintenance solutions area for more information.
The main underlying cause of poor curing is poor oxygen uptake into the film. This usually happens for either one of two reasons: Poor ventilation and recoating too quickly or aggressive ventilation too quickly (skinning over). Waterlox products like to penetrate into the wood to provide an excellent level of protection; however, it is more difficult for molecules to move around inside the wood substrate. This applies both for the solvent to escape from the wood, as well as for oxygen to get to the oils that are down in the wood surface. The proper amount of time and air flow is necessary to help drive the oxygen into the film and cure the coating. At the same time, being too aggressive with air flow immediately after application can cause the top of the coating to dry too quickly and seal in solvents and seal out oxygen from the liquid under that top film.
The harmful solvent vapors and odors will be gone from the coating in the first 6-8 hours. Any lingering odors are generally caused by uncured oils. These may be unpleasant, but they are not harmful. It would be similar to spilling olive or other cooking oil.
Grippy vs. Tacky
Most likely your coating is “grippy” and not actually tacky. A good test is to press a tissue firmly onto the surface. If it is truly tacky, the tissue will stick to the finish and be pulled apart. If it is just grippy, it will come off clean. Tacky finishes are usually an indication of some form of contamination or incompatibility. Something is preventing the molecules from cross-linking. This is extremely, extremely uncommon. Grippy finishes are relatively normal for the first few days. If it persists, it can be a sign that there was a problem during the curing of the coating. Along with a “grippy” feeling, there can be an issue of glossy magazines or plastic shopping bags sticking to the surface or transferring inks. This happens because the surface is still trying to cure and is essentially still active. Many modern inks and plasticizers will dry, but they are also not really “cured” so the two surfaces will interact. Getting the Waterlox surface cured will eliminate this issue.
How to Correct the Problem
If it has been many days or weeks since the last coat was applied and there seem to be lingering odors, the finish seems abnormally soft or if the surface feels grippy and bags/magazines/mail will stick if left for long periods of time, then it is best to address the problem. Typically, the issue can be addressed in as little as 24 hours.
The objective is to help oxygen get into the coating and finish curing the Waterlox. To accomplish this follow these few steps:
- Lightly sand the surface with 320-400 grit paper (a few passes by hand is all that is needed!) or lightly buff with 0000 steel wool or a maroon scotch brite pad.
- This will tear open the top film surface and make it easier for molecules to enter and exit the film.
- After sanding/buffing, clean up any debris (sweep/vacuum) and then wipe the surface down with a little bit of mineral spirits to pick up any stubborn dust.
- The critical step is to get air movement directly over the surface for 24 hours or at least overnight.
- The ideal tool is a box fan on a low to medium setting blowing directly over the surface. This ensures a fresh supply of oxygen molecules will constantly be flowing over the surface and increases the likelihood of finding an uncured molecule.
- A full 24 hours is ideal, any additional time will only ever be a good thing so if you can allow more time, do so.
- Any solvents or harmful vapors are essentially gone within the first 6-8 hours after coating, so exhausting the air is not critical. Exterior doors and windows can remain closed as long as there is good air circulation.
- Reapply one thin coat to restore the gloss and fill in the scratches. You can also leave the surface buffed down if you like the look. There are some good pointers in the tips for a smoother final finish guide about that procedure.
- Because we are just reapplying one coat, your surface will be ready for regular use in as little as 48 hours. You can carefully use the surface after 24 hours, but this top coat needs a little time to harden up.
The above procedure will work well on smaller projects, as well as entire floors.