Finishing With Penetrating Oils
External & Internal Applications
There are basically four alternative procedures to finishing an installation of timber cladding OR panelling with penetrating oil products :
- apply a finish to the completed surface on-site after the installation is complete.
- apply a finish to individual boards on-site prior to their installation with or without a further finishing coat after installation.
- install factory pre-coated boards and rely on the factory finish to be the final finish.
- install factory pre-finished boards and apply further final finishing after the installation is complete.
1. The Least Desirable Alternative
As changes in moisture content bring about changes in physical properties of timber, it is vital that it occurs as uniformly as possible. To assist achieving uniformity, it is important that if a coating is applied, it is applied to all surfaces. When applying a finish to a completed surface, it is not possible to achieve a coating all round and the performance of the finished installatiion is comprimised from the outset.
2. The on-site application of a coating prior to installation enables the back and edges of boards to be coated. This assists in achieving a more consistent response to changes in moisture content and will generally ensure better performance during the service life of the timber product. The application of a final finishing coat at the completion of the installation is also desirable for removing construction marks and similar blemishes which inevitably occur. This additional coat also evens out the overall appearance of the finish and is recommended.
3. The primary advantages from a factory pre-coated option are costs and thoroughness. Factory applied coatings do ensure that all surfaces are properly coated and that the coating material also extends into crevices created by a tongue & groove detail. The application is also much quicker and takes place in a covered environment, both of which achieve cost advantages. However, construction marking, other blemishes and some unevenness in the overall finish are likely to require further attention.
4. The Most Desirable Alternative.
While factory pre-coating clearly stands at the top of the preference list, to adequately address the construction marking and blemishes issues, a final coat manually applied on-site is recommended.
Furthermore, some factory applied finishing materials (particularly oils) do not dry as evenly as when they are manually brushed on and some final hand finishing on-site is also recommended to ensure the optimum finished surface is achieved.
In summary, when specifying penetrating oils, the best service and finish are obtained with one factory applied coating and at least one on-site coating after installation.
Finishing With Lacquers
As distinct from Penetrating Oil finishes, Lacquers do not a penetrate the wood fibre - they form a coating on the surface. In this respect, they are similar to paints and the latest technological advances with respect to product properties and their application generally ensure the highest quality result. Inevitably, the latest technology is related to factory based equipment and this generally precludes on-site procedures from being able to offer a similar quality of finish.
By and large, Lacquers are not suited to weather exposed applications. This restricts their applications to internal wall panelling and ceiling & soffit linings or external applications if they are subject to similar protection from the elements.
A factory applied pre-coating of Lacquer does provide the highest quality of finish which does not require any further finishing on site. For this reason, specifiers may consider the concealed fixing option offered by TIMBECK profiles to be appropriate for low shrinkage rate timbers and eliminate the need to deal with the result of face fixings penetrating the surface coating.
Lacquer finished products also require a much higher degree of protection on site to ensure that construction damage and other site induced blemishes do not occur. As indicated above, touch up work is detrimental to the high quality of the initial factory finish.