Coatings for windows and wood elements

Wood type: Siberian Larch

• Moderate durability
• Tendency towards moisture related movement
• Naturally occurring resins and tannins that migrate to the surface can result in some issues with the drying of coatings
• Low viscosity base coats can have difficulty absorbing into the dense surface of this timber

Wood type: Western Red Cedar

• Low density
• Ideal for cladding boards
• Does not resist physical damage and is quite brittle in thin sections
• High natural durability
• Opaque water-borne finishes can stain due to the very high water soluble extractive content, only specialist primers can stop extractives coming through paint finish

Wood type: Meranti

• Certain versions such as Dark Red Meranti show good durability and reasonable stability. If using other forms such as light red Meranti preservative treatment is necessary
• Some species of Meranti contain water-soluble extractives. On these, a stain inhibiting primer or mid coat should be used to ensure the extractives do not discolour the paint finish
• Many species contain a coarse grain structure. To avoid bubbling in the dry paint film, use a grain filling primer or mid coat

Wood type: Eucalyptus Grandis

• Good dimensional stability and durability
• A consistent supply of material with well controlled moisture content can be obtained
• Contains a coarse grain structure. To avoid bubbling in the dry paint film, use a grain filling primer or mid coat
• Lighter coloured material is not prone to excessive tannin staining

Wood type: Sapele

• Extractives in this species may discolour paint finishes and stain inhibiting primers are recommended
• There is a risk of moisture movement and twisting with this timber
• Unlike many other hardwoods this species does not have a very coarse grain structure and tends to give a smooth paint finish without the need for grain filling primers and mid coats

Wood type: Idigbo

• Very durable timber
• Does not require preservative treatment
• Idigbo contains highly water-soluble extractives which exhibit themselves as a yellow/green staining on light coloured paint finishes
• Dark tannins will leach out of the timber onto surrounding substrates such as masonry if the timber is not properly coated
• Specialist stain inhibiting primers are required when painting this species
• Dark staining can occur when ferrous fixings are used by mistake
• Coarse grain structure can cause trapped air in drying paint films leading to bubbles

Wood type: Scots Pine

• Moderate durability
• Moderate to low movement characteristics
• Low in dimensional stability and is non-durable against exterior wood rotting fungi
• The margins of live and dead knots contain extractives (tannins) that will create dark stains on light coloured paint finishes. When liquid resin diffuses through the surface coating, light coloured coatings can result in an amber/brown stain
• Target moisture content of timber prior to machining should be between 12 and 16%

Wood type: European Oak

• Excellent durability
• Prone to movement that leads to surface checks and splits
• Contains water soluble extractives which can result in staining of light coloured paint finishes. It is prudent to use stain inhibiting primers with this species
• Dark brown/black staining can occur when ferrous fixings are used by mistake
• Tannin staining at end grains under light coloured translucent finishes can be an issue

Wood type: Accoya®

• Radiata Pine is primarily used to produce Accoya®. It is a fast growing softwood species
• Known as acetylated wood. By chemically treated timber with a changed cellular composition that allows it to withstand temperature change and resist bacteria
• Extremely durable