Paint coating recommendations for film-forming finishes

Window Joinery and Doors

Water based enamel paints (so called because they replace alkyd enamel) that provide tougher more durable paint films are now available.

These acrylic paints are harder films that don’t stick together making them ideally suited for application on window joinery, doors and frames that touch when closed.

Prepare and prime as in previous tabs, use the recommended primer/undercoat of the selected paint brand, but if in doubt chose acrylic primer/undercoat.

If the joinery has been despatched with one coat pre-primed, follow instructions as in "Exterior Mouldings" tab.

Apply two coats of Water Based Enamel at a coverage rate of 12-14sqm/litre.

Once again from two coats not thinned you should expect a dry film of 50-60 microns from a paint at volume solids greater than 35%.

Don’t brush out too far as this will lower the effective dry film required for good exterior durability.

Furniture and hardwearing surfaces

Prepare and paint as in "Window joinery and Doors" tab,  using water based enamel paints.

For wooden decks etc refer to your selected paint brand for recommendations.

If in doubt follow the recommendations noted in "Window joinery and Doors" tab.

Where you plan to use water based enamel for decking paint make sure you apply extra coats in hard wearing areas as these films are relatively thin and can wear away over time.

Exterior wooden products not pre-primed

This may apply to either weatherboard or built elements such as pergolas.

• For weatherboard and window joinery you must first of all prime all surfaces with a full coat of alkyd or acrylic primer leaving no bare wood.

If subsequently a cut is made, re-prime that area with a brush applied two coats forced into the grain.

You can now proceed to prepare and paint as in previous tabs. To ensure no confusion, you should apply two primer/undercoats followed by two top coats.

When considering your options for what type of wood product to buy, take into account the fact that you can purchase one and two coat pre-primed product; it may be less expensive in the long run.

• For exterior pergola, landscaping materials etc, there is the option of using acrylic paints designed to be applied directly to the wood. This usually applies to solid sections such as landscaping poles, posts and structures rather than for weather and facia boards.

Most instructions on the paint can suggest direct application, however for best results you often see a primer/undercoat recommended. We concur with this recommendation as it adds to the film build and improves the overall performance of the paint. If you want to paint directly onto the wood consider a third coat.

Apply two or three coats of premium direct to timber 100% acrylic paint at a coverage rate of 12/14 sqm/litre/coat for best results.

Follow the preparation recommendations in "Surface Prep" tab, using the direct-to-timber acrylic selected as your end grain primer.

Once again cast your eyes over the whole area to ensure every surface is sealed off from water penetration.

Surface Preparation

For all applications, sand or clean to remove any surface contaminant that will impede the ability of the paint to stick to the wooden substrate.

Refer to Surface Preparation page for full details. Any bare timber must be primed immediately after surface preparation.

Priming cut ends prior to installation with two coats of primer, forced by brush into the grain, is also essential.

Priming

You can use either alkyd or acrylic primers depending on the recommendation of your selected brand.

Immediately prior or directly after installation, bare timber and cut ends should be primed.

At the same time punch and fill all nail holes, surface defects or installation damage with exterior grade filler, sand to a smooth surface and spot-prime.

Always check that you haven’t left any bare timber exposed.

Check that all sealants are correctly installed and flashings are in place and run your eye over all the exposed surfaces to make sure any areas where water can penetrate have been fully closed off.

Exterior 100% acrylic top coats

Once you have completed surface preparation and priming (follow previous tab) apply two coats of premium grade exterior house paint at 12-14 sqm/litre.

Note: at this recommended coverage rate on a product that has not been thinned, two coats will give a dry film of between 50-60 microns when the volume solids of the paint is greater than 35% (check with your paint supplier for the percentage of volume solids in their product) At this level of dry film, you can expect good exterior durability.

Weatherboard and exterior mouldings

Pre-primed with one coat alkyd primed (primed one coat):  Carry out surface preparation and priming as noted in "Surface Prep" and "Priming" tab, lightly sand the entire surface and then apply a full coat of premium exterior alkyd or acrylic primer/undercoat to all the surfaces. Apply this coat at 12/14 sqm/litre. Top coat as for "Furniture/hardwearing surfaces" tab.

Pre-primed with two coats alkyd primed (primed and undercoated): Carry out surface preparation and priming as noted in "Surface Prep" and "Priming" tab. You can use either alkyd or acrylic as a spot primer. Lightly sand the surface as required, removing or smoothing out surface defects. Spot prime any exposed bare wood. Top coat as per "Exterior 100% acrylic top-coats" tab.

Pre-primed two coats acrylic primed (primed and undercoated using acrylic primers and undercoats): For this range of materials you only use acrylic primers for spot priming. Carry out surface preparation as per "Surface Prep" tab. Using acrylic primer/undercoats follow "Priming" tab closely. Apply two coats as per "Exterior 100% acrylic top-coats" tab.