Ensure the timber surface is suitably prepared, clean and dry, with dust, dirt, wax and grease removed, and allowed to
acclimatise to its end-use environment. The moisture content should not exceed 18% prior to coating.Degrease any exposed bare timber surface by wiping with a cloth dampened with a suitable solvent. Certain timber species
contain high levels of natural wood extractives or exudates and some softwood can be highly resinous. Resinous deposits should be removed with a scraper. Any remaining residues should be removed using a lint-free cloth dampened with methylated spirits, frequently changing the face of the cloth. Allow solvent to evaporate fully before overcoating. The use
of both eye and hand protection is strongly advised.We do not recommend the use of “knotting agents” with Cetol BL Opaque, particularly on exterior work, as they are not
always fully effective in “sealing in” resin and they can impair coating adhesion.
The strong colour associated with knots in softwood, and generally with hardwood, is the result of natural chemicals known as extractives. Most of these are water-soluble and the colour can migrate into opaque coatings, resulting in discolouration when using light to medium shades of Cetol BL Opaque. The presence of a factory applied base stain or
primer is no guarantee against the possibility of extractive discolouration. Where there is a risk of it occurring, the use of Cetol BL Primer is recommended to minimise the problem.When filling, only use fillers specifically designed for use with timber. General or all-purpose fillers are not suitable,particularly on external areas, as they cannot cope with timber movement and work loose.
New Timber : Where a superficial application of preservative to softwood and hardwood is deemed necessary, such as timbers in Durability Class 3 or lower, use Cuprinol Wood Preserver Clear (BP). For Class 4 (in ground contact) and 5
(marine) use pre-treated wood specific for these conditions. Preservative pre-treatments must be fully dry before the
application of Cetol BL Opaque. Do not use on substrates which have had water-repellent preservative pre-treatments
applied. Where possible, the first coat should be applied all round prior to fixing.
Only use non-ferrous screws, nails and fixings. Base stained/primed : Denib using a fine grade nylon abrasive pad or a fine grade (P240 or finer) wet or dry silicon carbide abrasive paper, in the direction of the grain. Do not break through the surface coating. Remove all dust.
Note: Where there is localised damage, or deterioration has occurred as a result of exposure of the factory coating for longer
than 3 months, affected areas should be thoroughly sanded back to a sound substrate.All damaged or decayed timber must be removed and replaced, cutting at least 25mm into sound timber. When splicing in new sections consider whether the timber species natural durability is sufficient. Brush apply two coats of Cuprinol
Wood Preserver Clear (BP) to saturation. Thoroughly treat timbers, especially end grain sections, and ensure they are fully dry before splicing in. Secure with non-ferrous fixings and fill all voids surrounding the spliced-in area with a suitable repair compound such as Dry-Flex from Repair Care