There are two main processes when using a coating, which are both affected by temperature. Namely, application and wetting of the surface; and, drying and curing the film.
Application and Wetting:
Surface, Product and Room Temperature:
During application of Waterlox® wet-applied finishes (ORIGINAL, H2OLOX®, URETHANE or MARINE), the product, project surface and environment should be close in temperature and at least 50°F during application and at least 1-2 hours afterward. When both the product and surface are cold, they are less compatible. A cold surface has a low surface energy and may repel the Waterlox® product. It may bead up on the surface and not allow for a nice wet coat.
During application of Waterlox® buff-applied finishes (UNIVERSAL Tung Oil Sealer, TRUETONE®, and PURE Tung Oil), de-wetting is not as great a concern because these products are buffer-applied. The act of buffing/rubbing will drive these products into the wood, although when cold, they will be a little thicker and may require a little more effort to spread. Generally speaking, buffing/rubbing will generate heat and negate any low temperature effects.
Ideally, all application should occur when the products, surface and environment are above at least 50°F.
Prevention:
- Remove condensation (dew). Lightly dampen a rag with mineral spirits or paint thinner1 and wipe the wood surface between coats. Use a rag lightly dampened with water for Use a rag lightly dampened with water for the H2OLOX® products. This will pick up any remaining sanding dust, remove potential contaminants and condensation. The slightest amount of humidity is problematic.
- Once an even film has formed, lightly scuff the surface with 0000 steel wool or 400-grit paper (or equivalent) to create a better profile for inter-coat adhesion as well as remove minor surface imperfections. TIP: Do NOT abrade Waterlox Sealers or TRUETONE® Color-Infused stains. The bare wood will be exposed and the color will be removed respectively.
Correction:
- During application, if the finish starts to bead up, wipe off with a clean rag and wipe down with regular mineral spirits or paint thinner1 to remove the coat and get back to a clean surface. Use a rag lightly dampened with water for the H2OLOX® products. Then re-apply, lightly scuff the surface or wait for warmer temperatures.
- If the coat dries with imperfections, lightly sand to remove. Follow the same procedure as the Tips for A Smooth Final Finish guide. It should take very little effort to remove the imperfect coat.
Drying:
All Waterlox products are oxidative thermoset coatings; meaning that a chemical reaction takes place during the drying process where the oils and resins cross-link through exposure to Oxygen molecules. There are two factors driving the reaction forward in the favorable direction:
- Availability of Oxygen – Oxygen availability will be the easiest to control variable in the curing process, as well as the most important. The more oxygen, the more likely every available reaction site dry and cure without much effort.
- Temperature – Higher temperatures allow the molecules to move around faster, so it is more likely for an oxygen molecule to find an open reaction site and trigger the reaction. The molecules also have more free energy to overcome any other inhibiting factors.
Ventilation:
As with most finishes, Waterlox® products require ventilation. Projects can still be completed successfully in lower/colder temperatures, here are a few tips:
Solvent evaporation occurs in the first 2-4 hours; therefore, the focus is getting air from near the project exhausted to the outside. A fan directed outward in a nearby window brings in fresh air and removes the ‘used’ air. Ventilate outward for the first few hours and shift the focus to keeping the air circulating. For Waterlox® wet-applied finishes (ORIGINAL, H2OLOX®®, URETHANE or MARINE), do not blast air directly onto a surface immediately after coating as that can cause it to skin over and trap solvent. TIP: All windows do NOT need to be open as far as possible.
After the first 2-4 hours, most of the solvent has evaporated and the film should be mostly dry to the touch. It will still not be dry enough to walk on, but it should no longer trap any airborne dust. At this point, focus on maintaining air movement. A box fan on a low setting blowing gently over the surface will help IMMENSELY with the cure and also help to diminish any lingering odors quickly. Turn heaters back on (no open flames in the same room), partially close windows, etc. to help maintain a warmer environment. TIP: Air flow is always more important than warm temperatures.
- When finishing a smaller project in a large room (e.g.: a countertop in a garage), there is less of a need to keep exhausting a large amount of air to the outside. Keep the air circulating over the piece to always replenish fresh air to the surface.
- For directional air flow, use an inexpensive box fan on a low to medium setting for a gentle breeze. Forced air and ceiling fans will not be as effective.
- When in doubt INCREASE AIR MOVEMENT. After 24 hours, socked foot traffic is allowed, and if needed, windows can be closed, as long as air flow is maintained. Air circulation is the best way to help the cure process and will do the most for eliminating lingering odors.
1If regular mineral spirits or paint thinner is not available in your area, there are alternatives, visit Waterlox.com/mineralspirits.
