Flaking of stained wood finishes
Cause
Stained wood finishes are translucent/semi transparent.
The applied dry film thickness of these coatings are less than that of a traditional opaque paint finish.
These coatings, particularly light colours, can be affected by ultra violet rays that penetrate the dry film causing the underlying wood to become very dry and fibrous. The performance of translucent wood finishes can vary and special attention should be given particularly to exposed areas such a southerly elevations. For this reason window sills and styles may require attention and re-coating sooner than expected which in some cases can be every six months.
Note: On new building works were the timber items such as windows come to site with an initial stain coating applied they should recoated as soon as possible as the factory applied finish may not protect the underlying substrate from UV rays and can cause degradation of the timber fibers.
Remedy
All the defective coatings should be removed back to bare wood. This should be followed by thoroughly sanding down back to sound wood. All knots and sap residue should be coated with clear shellac knotting. Any areas of wood which need replacing due to damage, should be repaired using a suitable wood repair material. For glazing, linseed oil putty should be avoided and a suitable butyl glazing sealant used. Where repair fillers have been used there may be a slight colour difference. As these wood finishes are semi-translucent any difference in the colour of the surface to be coated will mirror through the newly applied coating. A test area should be carried out as it may be necessary to tint the first coat to match or use a slightly different shade. For redecoration work, if possible, always use the same manufacturers’ product and recommendations.
Repair Care. www.repair-care.co.uk
Available from all leading Paint manufacturers Trade stores and Decorators Merchants including:
Brewers Decorating Centres. – https://www.brewers.co.uk/stores
PaintWell – https://paintwell.co.uk/storelocator