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Osmo UV Protection Oil Extra

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Osmo UV Protection Oil Extra is a superior wood oil that protects timber against the greying effect of the Sun's UV rays by a factor of 12. It offers superb durability against weathering with an added biocide to combat insect attack and fungal growth.

Easily applied with a paint brush or mohair roller Osmo UV Protection Oil Extra dries to a satin-matt finish that will not peel, flake or blister.

Can also be used for lightening or overcoating the Osmo Natural Oil Wood Stain colour range.

  • Prices
  • Overview

Osmo 420 & 425 Overview

Perfect for use on all exterior timber including external doors, window frames, windowsills, carports, timber cladding, balcony, screens & fences, pergolas, garden houses, furniture and more.

Osmo UV Protection Oil Extra has been designed to combat the greying effects of the Sun's UV rays on exterior wood. Can be applied to a wide range of exterior soft and hard woods including Pine, Larch, Teak, Oak and Bamboo.

Exterior timbers turn grey or silver over time as a result of exposure to the sun and rain. Osmo UV oil acts as a 'sun cream for wood' slowing the greying process by a factor of 12 when compared to untreated wood.

Osmo 420 Extra and Osmo UV Protection Oil 425 Oak also contain Biocide which helps to protect timber from the onset of mould, algae and insect attack.

These UV Oils are micro-porous, thus allowing the wood to breathe. As the oil penetrates into the surface of the timber, it doesn't form a surface coating, so will not crack, peel, flake or blister. Osmo 420 clear and 425 Oak penetrate deep into the grain aiding the natural elasticity of the wood and helping to reduce shrinkage and swelling.

Osmo 420 clear & 425 Oak - Key Features

  • Based on natural, renewable resources
  • Final finish protects against mould, algae and fungai attack
  • Oiled finish provides a microporous, breathable surface
  • Foundation and top coat in one
  • For use on dimensionally/non dimensionally stable exterior wood
  • Dries in approximately 12 hours under normal conditions
  • 2.5Ltrs tin covers approximately 45 square meters based on 1 coat


Ensure surfaces to be oiled are clean, dry and free from all surface coatings such as paint or varnish before application. Wood that has been previously oiled should be cleaned and lightly sanded.

New unpreserved or old wood should first be treated with a quality wood preservative such as Barrettine Wood Preservative or Ronseal Total Wood Preservative before applying Osmo UV Protection Oil. Using a wood preserver prior to applying the oil gives additional protection against mould, algae, dry rot, woodworm and other wood boring insects. Allow sufficient time for the preservative to dry, normally 24 to 48 hours, before applying 'Osmo 420 Clear' or 'Osmo 425 Oak'.

As an alternative to spirit based preservatives Osmo WR Base Coat 4005 can be used. This product penetrates deeply into the wood to help repel water and moisture. This helps to reduce the risk of timber swelling and shrinking therefore reducing the chance of the wood cracking, splitting and warping. Note: this product does not contain an active insecticide.


Apply in thin coats with a paint brush or mohair roller ensuring that the oil is worked into the grain of the wood as opposed to painted on top of the wood. Always finish your brush or roller strokes by going in the direction of the wood grain. Osmo UV Protection Oil Extra 420 can also be applied over Osmo Natural Oil Woodstain as a top coat for added protection and durability.


Slightly tired looking areas can be easily refreshed by simply cleaning the affected areas and applying a fresh coat of Osmo UV Oil. Even badly scratched areas can be seamlessly repaired with a light sanding and a re-application of the oil.

Equipment Cleaning

Application brushes and other equipment should be cleaned with Osmo Brush Cleaner or White Spirit.


Osmo UV Protection Oil Extra has a shelf life of 5 years or more if kept sealed in the original tin. Store in a dry cool place. If thickened by cool temperatures or frost, the oil will regain its normal consistency within 24 to 36 hours of being returned to normal temperatures.

To preserve any remaining oil once the tin has been opened and used, decant any remaining oil into a smaller tin, jar or container, fill to the rim and seal with an air tight lid.


Osmo recommends that this product is NOT used on horizontal surfaces where water can collect such as floors, decking and wooden steps etc.


Q. We have a garden table which says only use Roble Wax and not Linseed Oil. I have searched for this product and even with the Internet have not succeeded. The table was from B&Q. Please can you help me?

A. To my knowledge, it's only B&Q that offers the Roble garden furniture in The UK and the product recommended for finishing it is indeed hard to find. We have looked into this thoroughly and can confirm that Osmo's UV Protection Oil is ideal for Roble wood. As Roble is a dense, oily wood it is important to work the oil into the wood well and apply it thinly.

Q. I work for a joinery that makes and fits bespoke hardwood windows, doors and decking. Can Osmo UV Protection Oil be used on dense exotic hardwoods like Teak, Iroko, Ipe, Garapa and Meranti?

A. On the tin it states that Osmo UV Protection Oil Extra is not suitable for use on Iroko, Teak and other exotic hardwood timbers but we have customers that have used Osmo UV Protection Oil with success on these woods.

Lightly sanding with a 120 grit sandpaper helps to open the tighter, less porous grain of exotic hardwoods enabling the oil to penetrate easier. Wiping the timber down with methylated spirit prior to applying Osmo UV Oil can help to remove some of the natural oil from the surface of the wood which helps the Osmo Oil to penetrate. Ensure the oil is at a good room temperature as it thickens when cooler making application more difficult. Apply thinly working the oil into the surface grain of the wood.

Q. Can Osmo UV Protection Oil 420 Clear be used on garden decking?

A. Osmo says that this product isn't suitable for use on horizontal surfaces such as decking. This said however, we have customers that have applied one coat of Osmo Decking Oil then applied 2 very thin coats of Osmo 420 clear on top and have been happy with the results.

Drying Time

Osmo UV Protection wood oil dries in approximately 12 hours in normal climatic conditions of 23℃ / 50% relative humidity. Lower temperatures and higher humidity can increase the drying time.

  • Reviews

Osmo UV Protection Oil Extra reviews - Rating: 4.8 out of 5 stars, based on 181 reviews.

Filter:   All reviews (181)   5 stars (151)   4 stars (27)   3 stars (2)   1 star (1)  

D Dyson

 2.5L, Clear - 420 Extra
First Class
Great product has transformed my summerhouse.
Andrew Peak

 2.5L, Oak - 425 Extra
Highly delighted with another fantastic product
Have used Osmo on all the bathroom furniture I build. Had a large decking to treat and although it's not the cheapest of products the outcome was worth every penny. Water now just runs off and everything looks new.....highly recommended.
Robert Preston

 750ml, Clear - 420 Extra
Easy to apply and the finish looks excellent.
I am very pleased with this product as they say it does what they say on the tin great finish goes on easily and my hardwood stills look very good after just one coat.
Michael Pender-Cudlip

 2.5L, Clear - 420 Extra
First class product despatched very efficiently and quickly
First class product despatched very efficiently and quickly
Peter Neachell

 750ml, Clear - 420 Extra
Very good product
I have used this product before & found it to be the best on the market for quality&price.
Mike Hammond

 2.5L, Oak - 425 Extra
Very good external product
Makes oak and all wood look dark brown, so blends into an old building. I am very pleased with this product as it has transformed my new white oak into an older looking and deeper colour.
Mike Pickett

 750ml, Clear - 420 Extra
Following on from the problem I had created with the wood stain I applied this material. Obviously some of the stain had remained in the grain of the timber, so when the oil was applied the original deep rich cover shone through. On the timber which had not been stained again the grain shone through. This was achieved with only one coat. Though I will be applying another coat.
Frank Richards

 750ml, Clear - 420 Extra
See below
I burnt off the original Sadolins coating on my conservatory before applying the Osmo. Excellent coverage, easy to apply and I am interested to see how well it weathers over the next couple of years.
Terry Abbott

 2.5L, Clear - 420 Extra
This was easy to apply and the finish was good
I was recommended this product through a different website and, although not cheap, it certainly covered the cabin well and produced the desired end product. A good quality brush certainly helped.

 2.5L, Clear - 420 Extra
Easy to apply; leaves wood a nice rich gold colour.
The product is easy to apply and leaves the wood a nice rich 'gold' colour. Only time will tell if the UV effect is retarded as stated by the company but I have every confidence that it will do as is described on the can.
Robert Smith

 750ml, Clear - 420 Extra
I am very pleased to have discovered Osmo oils!
I have used many osmo oils and been really pleased with all of them - internal floors and kitchen worktops; external doors and window sils. fantastic product and efficiently sent by Woodfinishesdirect.com
Jonathan Courtney

 750ml, Clear - 420 Extra
Excellent Product.
Used product to give 2 coats to my new Teak Bench and made an excellent job. Highly recommended and easily applied with a brush.

 2.5L, Clear - 420 Extra
Superb stuff
Bought two tins of this stuff for my exterior wooden windows and two doors. It is the best stuff I have ever used. After reading other reviews I decided on this make as opposed to Sadnolin or Ronseal that I almost bought. Gives an excellent clear matt finish and really shows the grain of the wood. Also the only stuff I've used that is genuinely clear not golden or orange. The wood was looking a little parched and now looks fantastic and well protected. Also seems to go a long way. Well worth the money.
David Lawson

 750ml, Clear - 420 Extra
Great product did what it said on the tin!!
Application was very smooth and finish was superb
David Allen

 2.5L, Clear - 420 Extra
First class product, easy to use.
I use the product on window frames and front door of oak, which are all south facing. Osmo keeps the colour of the oak looking as new without the grey, silvering associated with effect of U.V.
Pier Damico

 750ml, Clear - 420 Extra
Makes the timber gate look great
Excellent result. The gate I oiled is darker than I expected but it looks great.
Paul Manton

 2.5L, Clear - 420 Extra
Easy to apply, soaks in and leaves a nice finish
The finish is rich and natural. The product darkens the wood slightly but brings out the natural grain. I used it on Oak.
R Verghese

 750ml, Clear - 420 Extra
Good value easy to apply
Seems to provide a good oil based protection on two large Oak garage doors. I think I did the first coat too thick as it took longer to dry than advertised on the tin. Too early to tell if it works as I haven't hung the doors yet, but it looks, smells and touches 'good'.
Andrew Potter

 2.5L, Clear - 420 Extra
Good stuff
good coverage leaves a good finish easy to use
Allen Norris

 2.5L, Clear - 420 Extra
Good Stuff
Brushes on well and easy to use. Not too sticky and gives a good finish. Coverage seems better than advertised.

per litre
12 hours
dry time
  • Protects against greying
  • UV-Protection factor 12
  • Will not peel or flake

Coverage Calculator

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* Coverage can vary depending upon on the type of wood used and the amount of product applied. Litreage amounts shown above are total, not 'per coat' amounts.
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