The surface must be clean, dry and sound. Remove dust, grease, wax etc. using a suitable washing liquid. Rinse with clean water and allow to dry.
Resinous exudation. Any resin should be removed. The exudation of resin is a natural process and is virtually impossible to prevent. Jotun woodtstains have the advantage that they generally allow the resin to exude from the surface without damaging the film.
Knots. These can be treated with knot sealant priot to application of light colours of Demidekk Optimal or Trebitt, however some knot staining may still occur on certain species of wood as resin exudation cannot be prevented.
Mould, fungal growth or spores of fungi. They should be completely removed and treated with a disinfectant and allowed to dry.
Making good. To repair cracks, joints, holes or to renew glazing frontings, linseed oil putty can be used although butyl type putty or the more flexible glazing compounds are recommended. When larger cracks or holes need to be repaired, a two pack filler is recommended.
Mastics. If mastics are required, use and acrylic, polysuphide or polyurethane type of sealant. Silicone sealants cannot be painted. | The preparation will depend on the quality of the existing finish. If the existing surface is in good condition, rub down with fine sandpaper and wash down to obtain good adhesion. If the existing stain has started to break down (see section 'D' Weathered wood) stiff bruchsing and sanding is recommended followed by standard pretreatment. Jotun woodstains can be applied to previously stained timber. | Complete paint removal. All paint is removed by following the normal methods as detailed and then following the instructions for 'standard pretreatment'.
Methods of paint removal.
Burning off. Existing paint can be removed by using hot air strippers or burning off with a blow lamp, taking care not to scorch th timber. If scorching does occur then the burned wood must be removed by sanding.
Chemical stripper. Paint removers may be used in strict accordance with the manufacturers recommendations. All traces of chemical stripper must be completely washed off or neutralised.
Sanding. Remove all paint to bare wood using an electrical sander.
Part paint removal. All loose and peeling paint must be removed. Although complete paint removal is recommended, a good result can be obtained by removing paint from all sills and bottom sashes plus any other areas of paint failure, and then following instructions as for 'standard pretreatment'. If the bare wood has been exposed for a long period of time (6 weeks or more), sand down and apply one coat of Visir. The surface or any existing paint must be rubbed down. Jotun woodstains have excellent adhesion to traditional paint systems including alkyd glodd, provided the surfaces are sanded prior to application. | Even brief exposure of unprotected wood to weathering results in surface degredation. Six weeks exposure will destroy the lgnin in the wood, producing a less than adequate surface for painting or staining. The level of the surface degredation can be determined to some extent by using a simple test with adhesive tape, or scratching across the grain. Where weathering has occurred loose fibres must be removed from the surface by rubbbing down, sanding or stiff brushing. Apply one coat of Visir prior to application of Jotun woodstains. |
