A RATIONAL APPROACH TO THE BEAUTIFICATION AND PROTECTION OF WOODEN WINDOWS
Manufacturers of wooden windows and doors face a serious predicament - the long term “quality” of their product is frequently determined by the coating system used to beautify and protect their materials and workmanship. In many instances, window and door manufacturers have little if any control over the quality of the coatings used and the manner in which they are applied. It is in the best interest of window and door manufacturers, specifiers and homeowners that all parties be familiar with the specific characteristics required of a fenestration painting system.
The three greatest threats to a wooden window are ultra-violet radiation, moisture absorption and fungal spores.
Ultra-violet Radiation: New unpainted wooden windows are extremely vulnerable to damage resulting from ultra-violet radiation which rapidly breaks down the lignin binding wood cells together. UV radiation produces a fuzzy texture in unprimed/unpainted wood, which is an ideal environment for damaging microbes. It is absolutely critical that new windows be properly primed on all surfaces (interior and exterior) before such windows are installed and/or exposed to direct sunlight. We recommend a HOLLANDLAC or ECO paint system on new windows.
Under optimal conditions “all six sides” of every wood component will be primed by the manufacturer before assembly. Paints are far more effective than varnishes or semi-transparent finishes in repelling ultra-violet light, therefore, we do not recommend clear coatings on exterior wood.
Window manufacturers must take great care in selecting their raw materials to guard against the effects of moisture absorption before and after manufacture. Wood with high levels of moisture (greater than 15%) is extremely vulnerable to fungal damage leading to rot and discoloration. Wooden windows with high moisture levels create adhesion problems regardless of the quality of the coating used. Moisture absorption will also affect the dimensional stability of a wooden window which often results in operational difficulties.
We strongly recommend that window manufacturers utilize a moisture meter to test both raw materials and finished windows prior to the application of coatings. The inexpensive device will produce accurate empirical evidence of moisture content. Fungal Spores: Although fungal spores do not directly lead to wood damage, their presence on the surface of a window prevents the release of internal moisture. Ultimately, high levels of internal moisture, in turn, will create an ideal environment for fungal rot which can rapidly diminish the strength and appearance of a wooden window.
In order to protect a wooden window properly, all surfaces of the window and frame must be uniformly encapsulated with a coating system possessing at least 120 microns of dry film thickness. This encapsulation procedure may be accomplished by brush or spray application. Prime prior to glazing for optimal results.
In order to obtain a 5-mil thickness, it will normally be necessary to apply a system of four (4) coats of FPE finish. Typically, this 4-coat system will be comprised of one of the following combinations:
Two (2) coats Oil or ECO Primer/Undercoat
Two (2) coats Hollandlac Brilliant or ECO Brilliant or Satin
One (1) coat FPE Oil or ECO Primer/Undercoat
Three (3) coats HOLLANDLAC or ECO
Four (4) coats FPE Marine Yacht Varnish – Four coats is the absolute minimum, although we prefer to see six (6) coats. Be aware that first class boatyards apply twelve to fifteen coats on new work. We do not recommend the use of varnishes on the exterior of windows and doors unless clients are prepared to maintain the finish with an annual “dress coat”. The windows and doors must be maintained in the same manner as marine brightwork – neither practical or inexpensive
*Please note that we do not recommend the use of clear finishes on the exterior of windows, and doors. In situations where a clear finish is absolutely required, we suggest a full FPE Marine Varnish System (minimum four coats), which may be finished with one coat of Eurothane Satin or Matte Varnish if a lower gloss is desired. In the event that clear finishes are used on the interior of windows, they should be applied in a minimum system of three coats.