Osmo WR Base Coat (4001)

  4.8/5.0 (54 reviews)
1 coat = Recommended
Total: enter area

Wood type and application method can vary coverage.

  • New improved formula that replaces the old Osmo WR Base Coat 4005
  • Recommended in conjunction with exterior wood oils
  • Protects against mildew, rot, blue stain and wood boring insects
  • Greatly extends the life of softwoods and pines such as spruce, fir and hemlock
  • Penetrates deeply into the wood to repel water and reduce the risk of swelling and shrinking
  • Prevents swelling and shrinkage of timber
  • Dries to a clear finish
  • A unique combination of oil and water
  • Low odour formula
Brand Osmo
No. of coats 1
Coverage Up to 8 per litre
Drying time 12 hrs
Size 125ml, 750ml, 2.5L
MPN 4001A, 4001C, 4001D
GTIN 4006850103959, 4006850101863, 4006850101870

Osmo WR Base Coat (4001) is an exterior wood preservative that require protection against blue stain (EN 152), wood rot (EN 113) and wood-destroying insects (EN 46). It can be used on most exterior wooden surfaces including windows, frames, roller shutters, doors, pergolas, trellis and garden furniture.

Wood to be protected must be dimensionally sound and stable and not in direct contact with the ground.

  1. Wood surface must be clean, dry and frost-free (moisture content max. 20%) prior to application of Osmo WR Base Coat
  2. Clean old microporous stains thoroughly
  3. Old paints and lacquers must be completely removed to expose clean, bare wood
  4. Degrease bare wooden surfaces with meths if required

Always do a test area before starting any project to check suitability and compatibility. Stir well before use. Osmo WR Base Coat is ready to use and does not require thinning.

  1. Apply WR Base Coat by brushing, dipping or flooding
  2. Only spray apply in an enclosed unit
  3. Coat the clean, dry and frost-free wood generously
  4. Apply to all sides of the timber before fitting if possible

Please Note: This product is not for use on wood which comes into direct contact with food or animal feed. Also not for use in living spaces or habitable rooms. Do not use in immediate proximity of any kind of water.

Osmo WR Base Coat is intended as a protective base coat for exterior oil based products. It is therefore essential that it is over-coated with either an Osmo exterior wood oil or other suitable exterior wood oil.

54 customer reviews
Very successful product Performs exactly to the requirements it is specified to address by Andrew Clark

The product is a very good one which is appropriate for the job of protecting the wood without destroying its natural look. Its performance in UV screening and waterproofing the wood finish is all that was expected of a product of this quality.

Reviewed 750ml on: 17/03/17
Just used so won't know yet if it does what it should It goes on easy, its almost like water, but it means it soaks in deep to protect wood by Ian Robinson
Reviewed 750ml on: 21/02/17
Again easy to apply by Mr Neil Caunce

Again aplied with a foam roller for speed - went in good and deep !

Reviewed 2.5L on: 11/01/17
Primer for Yew table by Andrew Hird

Fine. No problems to apply. Container was covered in German writing. I need a translator to decipher what was said on the tin.

Reviewed 125ml on: 08/12/16
As described by Mr R W Marsden

i found this rather thin,so care should be taken in its application.

Reviewed 750ml on: 04/12/16
Easy to apply! by Stephen Lawley

The Osmo base coat is easy to apply by brush and soaks into the wood for first stage protection. You must put a top coat of an oil based product on top (I used the Osmo UV protection oil on cladding that I want to retain the colour of) but the base coat is the right first stage treatment.

Reviewed 2.5L on: 10/11/16
Easy application, time will tell for success by Robert Ashdown

After spending hours researching which wood preservative to use I decided on Osmo WR4001 with a clear top coat for my log cabin. The product is easy to apply. Only concern is every where on the internet states a single coat but the tin states for best results 2 coats. Purchased from wood finishes direct who offered an excellent service. They were very informative and helpful. I will definitely be using them to purchase my top coat.

Reviewed 2.5L on: 06/11/16
Easy to apply by Phillip.downham@gmail.com

Easy to apply and completely colourless. Too early to say if it provides the protection promised.

Reviewed 750ml on: 23/10/16
Excellent product, really easy to use and is as described by James Donovan
Reviewed 2.5L on: 19/10/16
Have not used it yet; am still rebuilding my decking by John Taylor

Have not used it yet; am still rebuilding my decking. However using it as a base coat on my new decking should make be great for added longevity of the overall structure.

Reviewed 2.5L on: 17/10/16
Easy to apply Soaks in and drys really well by Julian Marshall

It is extremely runny so covering up any surfaces nearby is essential. It drys quickly but it is essential to have cleaned off any ingrained dirt before application as it will not soak through that! I am yet to see what the Osmo top coat looks like but having used Osmo products for several years I am sure it will look great

Reviewed 750ml on: 09/10/16
Good stuff by Tim Goffe

See my more detailed comments for Osmo Country Colour Dove Blue for a garden Playhouse project.

Reviewed 750ml on: 16/09/16
Vital for any Osmo treatments by David Fielding

Provides the base to allow the finishing coats to do their job.

Reviewed 750ml on: 13/08/16
Very easy to apply by Richard

good product works well.

Reviewed 750ml on: 07/08/16
A good product by Charles

Went on well and the finished job (this base coat then the Osmo UV Protection Oil Extra) looks excellent. The door looks very good and it looks like it will be well protected.

Reviewed 750ml on: 23/07/16
A great base cost that I have used for years, wouldn't use anything else by Alastair Coss

If you use this under osmo paint, the finish lasts for 15 years, well so far.... Painted every 4 to 5 to refresh and the cabin is still perfect.

Reviewed 2.5L on: 20/07/16
Does absolutely what it says on the tin by Kym M

I have used a number of OSMO products over the years and have always found their quality to be excellent. Being easy to apply, low odour and giving long term performance value.

Reviewed 2.5L on: 05/07/16
Very good by Sarah Scott

Look good at the moment, time will tell

Reviewed 125ml on: 05/06/16
Easy to use by Kim

Applied this before applying Osmo one coat only HS plus on to blasted hardwood bench slats to give them extra protection. Definitely need amount suggested as the wood does absorb it as you brush it on.

Reviewed 2.5L on: 19/05/16
Coverage rate issue by Derek

Ordered the quantity on the basis of the stated coverage rate. There is something wrong with the stated coverage rate i.e. it is far too low. As a result I ended up with twice as much as I needed. Annoying as it is not cheap.

Reviewed 2.5L on: 06/04/16
A note from us...

Hi Derek,

Thank you for your feedback. The coverage calculators are there as a guide but many woods will take differing amounts. For example a rough sawn wood will absorb considerably more than a piece of wood sanded with a 240 grit sandpaper. And Pine will absorb more than Oak. There are many factors to consider, however if we find that this occurs more often we will get in touch with Osmo directly to discuss coverage details. If there is anything further that I can help with please feel free to get in touch.

All the Best Sam.