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Osmo WR Base Coat (4001)
A clear, exterior wood preserver that protects against mildew, rot, blue stain and wood boring insects whilst reducing wood swelling and shrinkage
Features
- Protects exterior wood against mildew, rot, blue stain and wood boring insects
- New improved formula that replaces the old Osmo WR Base Coat 4005
- Greatly extends the life of softwoods such as pine, spruce, fir and hemlock
- Effectively repels water to reduce the risk of swelling and shrinking
- Dries to a clear finish
- Low odour formula
- Very high V.O.C
Brand
Drying time
12 hrs
Coverage
Up to 6 m2 per litre
No. of coats
1
Size
750ml
2.5L
MPN
Please Select Size/Option
GTIN
Please Select Size/Option
Overview
Osmo WR Base Coat (4001) is an exterior wood preservative for use on wooden surfaces 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 prior to over-coating with a suitable exterior wood oil.
- For a biocide and preservative free alternative to this product, try Osmo Wood Protector (4006)
Please Note: This product is not recommended for use as a basecoat under Osmo UV Protection Oil Natural (429), that is designed to retain the natural, untreated finish of the wood. This product will enhance and darken the wood grain which is the opposite of what the natural UV protection oil is designed to do.
Using this product on rough sawn or featherboard wood will significantly reduce it's coverage.
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Preparation
Preparation
Back
Wood to be protected must be dimensionally sound and stable and not in direct contact with the ground.
- Wood surface must be clean, dry and frost-free (moisture content max. 20%) prior to application of Osmo WR Base Coat
- Clean old microporous stains thoroughly
- Old paints and lacquers must be completely removed to expose clean, bare wood
- Degrease bare wooden surfaces with meths if required
Application
Application
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Always do a test area before starting any project to assess product suitability and final finish. Stir well before use. Osmo WR Base Coat is ready to use and does not require thinning.
- Apply WR Base Coat with an Osmo Soft Tip Brush or by dipping or flooding
- Only spray apply in an enclosed unit and with a suitable spray system
- Coat the clean, dry and frost-free wood generously
- Apply to all sides of the timber including sides and end-grain 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.
Finishing
Finishing
Back
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.
Datasheets
Reviews
Reviews
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152 customer reviews
5.0/5.0
based on last 18+ months
5 stars
127
4 stars
23
3 stars
0
2 stars
0
1 star
2
Excellent product Easy to apply and the oak cart barn looks great
Purchased the Osmo Base Coat to treat the oak frame on a wooden cart barn that is used as a garage. I washed the oak first and that removed a lot of the grime. Put on one coat using a brush. The oil soaked in well and the oak looks great now. It is protecting he oak as water is not now soaking into the oak. I will apply a second coat when it stops raining. I used about 1.5 litres on the first coat. I have also an oak porch to treat as well and will be using Osmo again. Would recommend.
Roger. , 2.5L (10/06/26)
Quality
The foundation for ensuring our new accoya windows last 50 years.
Arthur Jones. , 2.5L (08/08/25)
Very good quick service
Good communication and service, will buy again
Devindar Takhar. , 2.5L (30/04/25)
Easy to apply, good coverage, enhanced protection for bare wood
Bought this to treat an external oak frame from any rot or insect attack, whilst allowing the natural silvering process to continue. We did not want to change the natural appearance or colour of the oak with other products that coat/darken and then require regular annual application. This base coat quickly soaked into the oak and dried to leave almost no visual change to the frame, but giving some peace of mind that there is now an enhanced element of weather and bio protection for the frame in the short/medium term.
John Southwell. , 750ml (23/04/25)
Very easy to apply great product
Great service and fantastic customer service about these products definitely use these products and more and this company
Dean Francomb. , 2.5L (15/03/25)
Great
I hope this product with the light oak 425 will last more than 3 years
Roger McArdle. , 750ml (18/09/24)
Easy to apply dries quickly
I used this the base coat my shed trim after having a few roof fitted. Then IK applied Osmo Country Colour an amazing finish
Patricia Hall. , 750ml (05/09/24)
Applies easily
Hard to evaluate a product designed for longevity in the short term. Only time will tell if it's good value.
Sandy Bates. , 2.5L (06/07/24)
Ok for now but too early to tell
Yes it’s clear, just slightly yellows timber on application. Whether it does all it says like reduce movement, protect timber from degradation etc, only time will tell.
Brushed on extremely easily and dried much quicker than advertised but was applied to new and sanded timber which absorbed it well.
Andy B. , 750ml (02/07/24)
Great Base Coat for outdoor garden bench
I spent several days sanding down a beautiful wooden garden bench as previous owner applied paint/varnish. I applied the Osmo WR base coat 1st for added protection, just the one coat and let it dry for 24hrs. I then applied the Osmo Natural Oil Woodstain (Oak) making sure I had a few good dry days (weather wise) and very happy with the finish outcome. The wood stain really enhanced the natural wood and you can tell by the look that the Osmo Woodstain Oil is an excellent product. I found that applying with a cloth rather than paint brush was far easier, less messy and you use less oil.
Adrian Dow. , 750ml (13/06/24)
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