Painting wood with knots

How to Cover Knots in Wood Before Painting

Begin by spot-priming the knots with our specialised primer Zinsser B-I-N®. For a water-based alternative, B-I-N® AQUA will also effectively block knots and sap streaks, with the added benefit of low odour and full exterior use. Once the knots are properly sealed, you can proceed to prime the entire surface.

For the best results, apply multiple coats of primer to ensure complete coverage and durability. Generally, two coats are recommended.

B-I-N will be touch dry in 15 minutes and recoatable in 45 minutes.
B-I-N AQUA will be touch dry in 25 minutes and recoatable in 45 minutes. However, for knots and stains, it’s crucial to allow the full 2-hour drying time before applying additional coats.

If painting resinous timber only, prime overall with one full coat of Cover Stain and allow a minimum drying time of 2 hours in normal drying conditions.

How to Paint Wood with Knots

Prepare the surface

• Begin by thoroughly cleaning the wood to remove dust, dirt, and grease. Our Universal Degreaser & Cleaner is the perfect option for this. Rinse and allow it to dry completely.
• Lightly sand the wood to create a smooth, even surface and to help the primer adhere better. Use fine-grit sandpaper (120-150 grit) for this step. For knotty areas, ensure you sand them slightly to remove any loose resin.
• Inspect the wood for any cracks, holes, or imperfections. Fill these areas with a suitable wood filler and allow it to dry. Sand the filled areas until smooth.

Prime the knots

• You can remove any excess resin from knots and other resinous timber by using a hot air stripper. Wipe immediately with methylated spirit to remove residue.
• Apply Zinsser B-I-N® or B-I-N® AQUA directly to the knots. This primer is effective in sealing the resinous areas and preventing stains from bleeding through the paint.

Prime the entire surface

• Once the knots are sealed, prime the entire wood surface with the same primer. This will ensure uniform coverage and a solid base for your topcoat. Apply two coats, allowing adequate drying time between each.

Properly painting wood with knots requires careful preparation—but the results are well worth the effort. By cleaning, sanding, filling and priming the wood before applying high-quality paint PermaWhite or Zinsser AllCoat Exterior Water-Based you can ensure a smooth, durable finish that will stand the test of time. Remember to allow sufficient drying time between coats, especially when dealing with knots and stains.

Find out more about the primer paint range here.