*Thorndown Paints™ are delivered FREE on a next working day delivery (if ordered early enough for us to process and pack), however some remote areas may take a bit longer. Please see more delivery information here.


Thorndown Stain Blocking Primer

THORNDOWN Stain Blocking Primer. Ideal for use below all wood paints and wood stains. Available in 4x colours.

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THORNDOWN Stain Blocking Primer

Thorndown Stain Blocking Primer is a high performing multi-surface primer primarily developed for tannin and stain blocking on timber surfaces. It’s formulated to work on all softwood and hardwood including pressure-treated timber, Accoya, Iroko, plywood, MDF and hardboard. Thorndown Stain Blocking Primer blocks stubborn and persistent stains including water stains, marker pens, and seals porous surfaces with excellent blocking of bleeding knots and sap streaks.

Thorndown Stain Blocking Primer also contains flash rust inhibitor to stop rust forming and fungicide film preservation to stop paint film degrading with mould. It’s easy to keep your paint job looking great by applying a base coat of Thorndown stain blocking primer first, stopping tannins from wood coming through and staining your paint coating. For use on any wood, anywhere.

Thorndown Stain Blocking Primer works perfectly with all Thorndown wood paints, there is a choice of stain blocking primer in clear for translucent wood paint colours, UV Clear, and semi-opaque colours, white for whites, off-whites, creams and light colours, grey for all mid to darker tones, and a black.


  • 2x Sizes – 750ml & 2.5L
  • Made in the UK
  • Perfect for softwood and hardwood, including pine, cedar, redwood, plywood, MDF and hardboard
  • Works on all painted surfaces of timber, masonry and plaster
  • Quick drying – dry in 1 hour in fine weather conditions
  • Available in Clear, White, Grey and Black
  • Water-based primer, sealer and stain killer
  • Thorndown Stain Blocking Primer is suitable for use on interior and exterior surfaces
  • Excellent adhesion to all timber and painted surfaces
  • Blocks stubborn and persistent stains including water stains, marker pens and more
  • Thorndown Stain Blocking Primer seals porous surfaces with excellent blocking of bleeding knots and sap streaks
  • Flash rust inhibitor prevents rust forming while drying
  • Fungicide film preservation stops the paint film degrading with mould
  • Stunning, carefully crafted high performance Eco paint – water-based eco product with minimal VOC (Volatile Organic Compounds) at 0.28%, and low odour


Thorndown Stain Blocking Primer comes in a choice of Clear (for translucent wood paint colours, UV Clear, and semi-opaque colours), White (for whites, off-whites, creams and light colours), Grey (for all mid to darker tones), and a Black.

Application Guide

What you’ll need: Brush, roller (use a foam roller sleeve) or sprayer; whichever colours you want (or want to mix and match); imagination.

Preparation: For best results, sand surfaces and use a wood preservative if needed on untreated fresh timber.

Application: Use a brush, roller, or HVLP sprayer. ‘Avoid the rain, and apply with the grain’, as they say, and leave to dry. When coating large areas, paint up to still-wet paint, as applying over dry paint can make things look uneven.

Coats: Only 1 coat is needed but you can apply a second on particularly resinous or troublesome wood, like very knotty woods or ones with high tannin bleed or leeching.

Drying: In fine weather, a single coat dries easily in an hour or two (20°C and low humidity), ready to paint on a second coat if required, or to apply a paint top coat.

Cleaning Up: Use hot or cold water, with or without detergent, on paint-wet equipment. Be very careful not to allow sprayer nozzles to dry out – this will make cleaning them almost impossible!

Disposal: Please, please don’t throw away unused or dried paint or preserver into drains or watercourses. Most local authorities have free facilities for disposing of paint and coatings. Tins are fully recyclable but remember to make sure they’re clean.

Coverage: You’ll paint 6m² – 12m² of timber surface (one coat) with one litre; rough sawn surfaces will take a lot more paint than a smooth surface, and second coats take less than the first. So each paint can will do approximately:

  • 750ml up to 4.5m²
  • 2.5L up to 15m²

Storage: Paint will keep for approx. 2 years or more in a sealed tin stored out of freezing or extremely high temperatures. Mix well before use.


Beauty is in the eye of the beholder, and so is colour. We all see and interpret colour slightly differently to each other, as do our VDU screens, software and printers that we use. The colour swatches you see on screen and on a printed colour chart are designed as a guide.

The exact and final colour you paint up at home will look slightly different depending on the material you paint it onto and the lighting. For example a colour painted onto new softwood will look slightly different if painted on old hardwood. If you paint up a wooden planter the colour will look different depending on the lighting and where you put it in the garden.

We always recommend trying a small tin at home, where it’s going to end up. Our colours are made precisely using a technically engineered colour system ensuring continuity of colour throughout batches.