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Boiled Linseed Oil: For Wood and Metal

About Boiled Linseed Oil

Found in most woodworker’s workshops, as well as in trade shops up and down the UK, boiled linseed oil is a popular product at Rawlins Paints.

Also known as BLO (an acronym of Boiled Linseed Oil), this wood treatment is an oil treatment primarily for interior use, which leaves a lovely and smooth finish on a wooden surface – almost with a wet look. Like the kiss of life, it can transform old, worn out and dried wood to better its former glory.

A before and after view of boiled linseed oil on wood

Fun Fact: This type of linseed oil used to be a common addition to most paints. Still available from specialist companies, it can still, on its own, be mixed with other finishes.

There are other wood finishes that treat surfaces in a different way, such as waxes, which ‘set’ the surface, sitting on it and buffing it to the desired finish. There are also other types of linseed oil, including pure linseed oil and polymerized linseed oil (which has been half treated).

Click to read:

  1. Boiled Linseed Oil – Its Many Uses
  2. How to Apply Boiled Linseed Oil
  3. The Dried Out Finish
  4. Removing Boiled Linseed Oil
  5. Boiled Linseed Oil – Product Focus
  6. Health and Safety

Boiled Linseed Oil – Its Many Uses

Deceptively recognised as a wood treatment, it can also be used on metal.

BLO protects wooden surfaces with its deep penetration, soaking into the grain and bringing out added contrast and character. Rather than being a surface treatment, boiled linseed oil soaks deep into the wooden fibres, to the core of smaller depth pieces of wood, strengthening it throughout.

You may find it used on:

  • Tables, chairs and other furniture
  • Guitars – electric and acoustic, on the body and neck
  • Flooring
  • Bannisters and handrails
  • Cabinets, cupboards and worktops
  • Rifles
  • Interior decking and seating – boats and caravans
  • Garden benches
  • Interior and exterior doors
  • Speaker cabinets
  • Dinner trays
  • Wooden models and craft items, such as cars and jewellery boxes
  • Shelving and mantelpieces
  • Toy boxes, chests and trunks
  • Breadbins
  • Structural beams
  • Old tool handles
  • Ornate decorations on bedsteads, cradles and cots

Boiled linseed oil can transform ornately decorated wood

Fun Fact: Boiled linseed oil has not actually been boiled, but is chemically modified with metallic solvents for faster drying times. Standard or raw linseed oil can take weeks to dry, sometimes longer – making that the main difference between the two types of linseed oil.

It’s not just wood that boiled linseed oil protects, it also helps preserve metal, by protecting the surface from oxidation. Thin coatings work best, as thicker application coatings can take longer to dry and get, what is known in the trade, as ‘gummy’.

Generally, only applied to non-moving parts of workshop tools, such as chisels, block planes, screwdrivers or treasured (and no longer used) heirloom tools, it can also be used on cast iron surfaces of bigger tools – table and band saws for example.

Use boiled linseed oil to restore old metal tools

How to Apply Boiled Linseed Oil

Boiled linseed oil is applied with a rag, or a similar buffering cloth. This is dipped into the linseed oil and rubbed into the wood – straight up and down the grain, or in slow buffering circles. Gloves should be worn at all time during the handling and application process of linseed oils.

Remember, as discussed earlier, to apply thin layers and not at any point by pouring the boiled linseed oil onto a surface.

Where possible, as with all paints and wood finishes sold at Rawlins Paints, it is best to test boiled linseed oil on a small area first, before applying full coverage. It may take between 24-72 hours for BLO to fully cure, or dry out to the touch.

Dry, bare wood is like a sponge and will soak up almost anything applied to its surface, and boiled linseed oil is one of many wood preparation products available, and acts as a good wood sealer to make surfaces much more water resistant.

Nearly all wooden surfaces will contract and expand through humidity and seasonal weather, which is where this type of linseed oil is great, as it is flexible and will continue to protect the wood through these changes over time.

The Dried Out Finish

Similar to some other solvent based products, boiled linseed oil is cured by its interaction and chemical reaction with oxygen. Water based paints and products ‘cure’ by water evaporating, emitting low VOCs and are not heat reactive to the touch. BLO when it dries does create heat, in part of its chemical reaction with oxygen. Because of this there may be recommendations on a product for drying out (curing time) exposure to sunlight or other heat sources (ovens, radiators, naked flames).

Chemistry states that lower usage of the product will create lower heat generating reactions, compared to larger application areas and density of the coating treatment creating potentially much bigger heat generation risk.

Removing Boiled Linseed Oil

The best technique to prepare a wooden surface for a treatment other than boiled linseed oil is to use sandpaper and a lot of elbow grease. As the oil soaks deep into the wood, you’ll be looking to prepare only the surface’s cured coating, removing as much of the linseed oil as possible.

Boiled Linseed Oil – Product Focus

Blackfriar’s boiled linseed oil works very well on most woods, with the exception of oak, and can be used inside and outside on soft and hard woods. Leaving a ruby ‘tint’ to a bare wood surface, it is water resistant and has a light gloss finish. As well as sealing woods, it works as a softener for metal glazing putty. Every workshop should have a canister of Blackfriar’s boiled linseed oil in a cupboard.

Blackfriar's boiled linseed oil is available to buy at Rawlins Paints

Health and Safety

Boiled linseed oil does come with a strong warning that it is a very flammable material and incorrect storage can lead to spontaneous combustion. All product datasheets should indicate strict storage recommendations – including temperature, humidity, sunlight exposure, etc. for the storage area. If in doubt, please contact us prior to ‘forgetting’ about it and leaving it in an unsuitable environment.

Do not store boiled linseed oil in anything but the metal container it is packaged in. For application purposes, plastic containers can be used – for ease of use – but never simply cover and store the plastic tubs.

One application method is to use a dry rag. After use, however, lay flat the rag on a non-flammable surface (concrete), away from potential heat/flame sources, until dry. Alternately, like the oil itself, the rag can be stored in a metal container. Never discard a used rag, as this can be a huge fire risk – the ‘screwed up’ and discarded rag can be a lot more heat reactive and combustible due to lack of air ventilation to cool the oil down. Used rags can be flash points, and at all times through the preparation, usage and cleaning-away process, all materials must be considered fire risks if inappropriately used and stored.

Fun Fact: When Tutankhamun was buried, the linen clothes that embalmed him were covered in linseed oil – but due to it being a rushed ‘ceremony’, the linseed oil did not have sufficient curing time and it may have spontaneously combusted. Let that be a warning to cleaning out the rags used to apply boiled linseed oil!

26 comments

  1. my sons and I are whittling and carving walking sticks. We’d like to maintain the beautiful natural color of the wood. Which product or oil would you recommend that will both preserve the natural coloration, while also providing adequate protection for the wood?
    Thank you kindly.

  2. We are in the process of repainting our castle entry iron doors and were wondering if the boiled linseed oil would help to protect the doors after the final coat of paint is applied. The plan was rag apply to the doors and not brush on. Please reply back with any thoughts or other recommendations. Thanks, Jim

    • Hi Jim,

      Linseed Oil has to penetrate in to timber to provide the protection so would not be suitable for application over a painted surface. We could offer Rust-Oleum 4900 Polycoat 2K as a clear coating to be applied over a painted surface for extra durability.

      Hope that helps – feel free to come back to us if you require any further help.

  3. Hi,

    I am looking for a suitable oil to apply to some old oak doors on our local church. I was recommended linseed oil by the architect but your guidance says not to use on external oak. The doors are over 100 years old so are well weathered. One is protected by a porch but the other is not. The church is grade 2 listed so the appearance should not be changed dramatically.

    What would you recommend ?

    Thanks

    • Good afternoon Keith,

      We would recommend Coo-Var Danish Oil for this – which you can find here.

      Coo-Var Danish Oil is a hard, durable, water resistant seal for the enhancement of interior and exterior wood. It contains tung oil, and is ideal for use on mahogany, teak and most other timbers.

      Please let me know if there is anything else I can help you with.

      Best regards.

      Mark

  4. Hello, I have been told to apply linseed oil to the rubber seals of uPVC window to eliminate draughts. Is this advisable please

    • Hi John,

      We have checked with our suppliers and they are not familiar with the process, so we couldn’t recommend Linseed Oil for this application.

  5. I am refurbishing some vintage kitchen scales. They have a tinned steel pan on top . The tinning is worn through in places. I am considering using a thin cost of BLO to give an attractive and protective finish. The scales will be primarily for display but an occasional use , just for the tradition, may be the case. Your thoughts on BLO.

    • Hi David,

      We can only recommend the use of boiled linseed oil on timber. There are instances where it can be applied to metal such as workshop tools, but you would need to contact the manufacturer of the item to check compatibility.

  6. Good day,

    I have a sliding glass door with a wooden frame. Would you recommend BLO or some other finish to keep the natural beauty and increase weather resistance. The door is in the living room (we have natural wood trim and baseboards) so a natural finish is preferred.
    Thanks,

    • Hello Eric,

      As we’re unsure which wood the frame is made from, we would recommend using Blackfriar Danish Oil. This may be used inside or out, contains a UV protector and gives a satin lustre finish to the wood.

      The manufacturer says that 4 coats should be applied at a coverage rate of approximately 14m2/L/coat.

      Hope that helps – certainly come back to us if you need any further help.

  7. Hi,

    I am planning to renovate a G-Plan Teak dining table and chairs – would welcome any advice on preparation and which products to use.

    Thanks Garry

    • Hi Garry,

      My apologies for the delay in answering your question; surfaces should be clean, dry, sound and free of contaminants. Sandpaper can be used to remove any unwanted coatings or paint and it should then be left to dry for 1-2 weeks before applying Coo-Var Siliconised Teak Oil.

  8. How long should boiled linseed oil cure after application before applying wipe on polyurethane?

    • Hello Peter,

      The Boiled Linseed Oil would need to be fully cured and ideally be weathered; if it is freshly applied Boiled Linseed Oil we would recommend allowing a minimum of 7 days before applying anything over it and would recommend trial application to ensure adequate adhesion and absorption of the wipe on polyurethane is achieved.

  9. i have recently built a work bench and used boiled linseed oil to finish the wood, its the wood more flammable while the linseed oil dries? All rags have been safely disposed, I am just curious about the wooden bench being a fire hazard.

    • Hi Douglas,

      Thanks for your message. Boiled Linseed Oil is white spirit based and as such, the coating would be flammable. Oils applied to a timber surface are designed to not fully, physically dry so in short, the use of an oil could increase the flammability risk of the bench. We haven’t fire resistant coatings or systems that would be suitable for application over the oil, we could offer a treatment for application on bare timber but this can only be overcoated with a water based topcoat, not oil based: Zeroflame Fire Retardant Treatment.

  10. Hello
    I use indoor teak wood for decoration in the living room, the wood was varnished and painted .
    One big problem is that the wood now full of kind of white dust!!!!
    I have used vaseline, cleaning soap, to remove , it removed and the day after it returned back . I do not know how to deal with that problem.
    Please advise.

    • Hi Sabera,

      This sounds like efflorescence coming through due to moisture from behind. No simple solution to this I’m afraid, it would be a case of removing the timber, treating the moisture issue behind and then try to clean the timber and let it dry out so it can be reinstalled. Worst case scenario is the timber needs replacing.

  11. Hello, I have many pieces of furniture made of rimu pine from NZ. I have sanded the tops back to a raw finish with fine sandpaper. The rest I have given a light sand to remove the shine. The manufacturer said originally the furniture was oiled with a 10% lacquer finish. They suggested boiled linseed oil and then a wax. I am worried the colours of the furniture will not blend as parts are raw and other parts not. what do you suggest.

    • Hi Gina,

      We’d recommend preparing the remainder of the furniture to match the top so the base colour is the same prior to application of a finish.

  12. We have fixed some oak faced plywood to the frontage of the alter area in my local church and would like to deepen the colour to something closer to the main alter which is a 100 year old golden oak hue. Clearly we won’t be able to get a close match and so far we have applied 3 coats of boiler linseed oil which has certainly coloured the bare plywood but would like something a little deeper /darker tone. What wood oils would you suggest might be applied over the BDO to help us achieve a deeper tone? Is teak oil or danish oil naturally darker?
    Thanks for your time and consideration.
    John Garvey

    • Hello John,

      Thank you for your comment.

      With these types of oil, they are predominantly clear so are really used to bring out the natural colour of the timber they are being applied to. The timber will only darken as much as the tannins in the timber will allow it to without applying a coloured varnish or oil.

      We currently have nothing we could recommend for application over the existing finish that has been applied I’m afraid.

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