Why is the surface still sticky after application?
Extended drying times and sticky surfaces are often the result of over-application. There are several other reasons as to why this may occur however, which all relate specifically to a lack of oil penetration. Osmo finishes must always absorb the surface of the wood.
Please check carefully if any of the following is applicable:
A maximum of two thinly applied coats is recommended with brush or roller applications. A maximum of four thinly applied coats is recommended with cloth applications. Applying thickly or generously results in very little or no penetration, whilst an excessive number of applications leaves surplus oil to remain on the surface. Over-application not only extends the drying time, but also creates a sticky/tacky surface which attracts the likes of dust, dirt and lint. The surface may also become more susceptible to scratches and wear more quickly.
Remedy: allow for extra ventilation and remove excess application immediately with a clean and dry cloth. If the excess has already dried, the use of methylated spirit helps to degrease the surface from the excess. Depending on the amount of excess, sanding may be necessary.
Varnishes, lacquers and other surface coatings block the absorption of oil into the wood.
Remedy: sand the surface completely and re-apply.
Unsuitable for the Wood
Ingredient-rich hardwoods such as Teak, Mahogany, Iroko, Cedar etc. naturally contain a high amount of oils or resin, thereby the addition of further oil is likely to result in excess/surplus on the surface. Special products have been developed to absorb these types of woods, be sure that you are using the most suitable product for the wood it is being applied to.
Remedy: for ingredient-rich woods used in the interior we recommend a very thin application of Wood Wax Finish Extra Thin 1101. Whilst for exterior use, a weathering period of at least 12 weeks is required to allow the natural extraction of the wood’s content before a thin application of a suitable exterior product is possible. The weathering period is applicable to new (ingredient-rich) timber species, after installation and/or sanding.
Sanding Too Finely
When sanding, P120 is generally the most ideal finishing sanding grade to best prepare the wood’s surface for application of Osmo products. A maximum grade of P240 is possible for cloth applications only. The use of finer sanding grades further closes the grain and reduces the surface porosity, thereby resulting with surface excess and extended drying times.
Remedy: degrease the surface with methylated spirit to reduce any surface excess where possible, followed by sanding the surface using most suitable grade of sandpaper for the wood you have and for your choice of application method.
The area of application must be well ventilated and in dry conditions. The ideal temperature for application is 23°C with 50% relative humidity. Lower temperatures and/or higher air humidity can increase drying times.