Does timber have to be primed before using?

Treating wood can be a minefield with so many products to choose from - not to mention the array of characteristics found in different types of timber.

Typically more care is needed with softwoods due to weaknesses like knots, splits, lack of durability, blue stain, etc, but the tendency with hardwoods is to retain the natural grain appearance, often resulting in under-application of coating, and subsequent earlier breakdown.

That said, some hardwoods can be very difficult to paint because they have an oily surface (see notes below). The key before an application is to remove all surface oils using cellulose thinner and rinse with clean water.

Prone to tannin bleed

Coloured timbers such as oak, Western red cedar and idigbo are prone to tannin bleed. Degrease with cellulose thinner and ensure the timber is thoroughly coated all round (with particular attention to end grains).

Contains acidic tannins which discolour with metal fixings

Hardwoods including Oak, Western Red Cedar and Idigbo. Degrease with cellulose thinners and avoid the use of steel (ferrous) fixings.

Contain oils/gums/extractives (slow drying and poor adhesion)

Hardwoods including Teak, Iroko and Keruing. Degrease with cellulose thinners and allow extra drying time.

Exterior Hardwoods

Priming Options

1. Ultra Primer
2. Pinja Flex Combi 25

Intermediate

1. Pinja Flex Isolator (exterior blocking primer)

Topcoat Options

1. 1. Ultra Matt
   2. Ultra Classic
   3. Valtti Opaque
   4. Unica Semi-Gloss Enamel
   5. Unica Akva
   6. Valtti Teho
   7. Pinja Flex Combi 25

 

Interior Hardwoods

Priming Options

1. Ultra Primer
2. Akvi Primer (Spray Only, Fast Drying)

Intermediate

1. Multistop (ensure left to dry for 24 hours before topcoat)
2. Akvi Isolator (ensure left to dry for 24 hours before topcoat)

Topcoat Options

1. Everal Aqua 10, Everal Aqua 40 or Everal Aqua 80, depending on the sheen level required
2. Helmi 10, Helmi 30 or Helmi 80, depending on the sheen level required
3. Akvi Top DS25

Lacquering Options

1. Kiva 10, Kiva 30, or Kiva 70, depending on the sheen level required
2. Akvilac FD-J 10

 

Softwoods usually grow quicker than hardwoods and are cheaper, softer, and easier to work. They are often used to make furniture, paneling, and all sorts of other things. While softwoods aren't tough to paint, they come with a problem called colour bleeding. This is an issue especially with knotty softwoods since the knots leak more resin, leaving a stain. Stopping this resin can be very challenging. Blocking primers such as Multistop for interior wood or Pinja Flex Isolator for exterior can and do help, but heat sealing can provide a more effective solution:

1. Scrape away excess resin.
2. Heat knots with heat gun and again scrape away excess resin.
3. Once complete, wash down all oily surfaces with cellulose thinner, then rinse with clean water.
4. Allow timber to settle

 

Interior Softwoods

Prime with Ultra Primer.

Topcoat options

1. Everal Aqua 10, Everal Aqua 40 or Everal Aqua 80, depending on sheen level required
2. Helmi 10, Helmi 30 or Helmi 80, depending on sheen level required
3. Empire Furniture Paint

Exterior Softwoods

Prime with Ultra Primer.

Topcoat options

1. Ultra Matt
2. Ultra Classic
3. Valtti Opaque

In summary, Ultra Primer can be used on most woods, but if in any doubt or you require specific advice on your project, please give our technical team a call on 0131 334 4999 or send a message here.