Thursday, February 23, 2017

Experiment: Making My Own Cold Bleached Linseed Oil

I was always happy with standard boiled linseed oil (BLO). It's got a lot of great things going for it: it's widely available at any hardware store, it looks great as a finish on it's own, it can be combined with other things to make different finishes, it makes a great wipe-on finish, etc.

My only beef with it for a long time is the smell.

It turns out that BLO isn't boiled at all. Nowadays, raw linseed oil (which works as a finish, but takes weeks to dry making it unhandy) is mass produced by adding metallic chemical drying agents such as manganese and cobalt which through the magic of chemistry makes the linseed oil dry relatively quickly.

A quick internet search produced a Material Safety Data Sheet (MSDS) for some BLO, which includes this:

Effects of Overexposure:
Inhalation:  Vapors may cause irritation of the respiratory tract.
Skin:  Prolonged or repeated skin contact may cause irritation or dermatitis.
Eyes:  Contact with eyes may cause burning and tearing.
Ingestion:  Ingestion of large amounts may cause gastrointestinal irritation.
Chronic:  Not Available.

Overall, it looks pretty safe. But not totally. I wouldn't drink it.

Then, I was ruined by Dictum. They sell a Swedish cold-bleached linseed oil.
Linseed oil from Dictum. Also, some great smelling turpentine balsam, and some natural tung oil from Denmark.
This stuff is great. No chemicals, it smells great, and it works fantastic! After a little bit of research, I think I know how this was made, and I am going to try to replicate it in my apartment.

What could go wrong?

The first thing I found was this great YouTube video by Joe Besch:
His website led me to a page on Tad Spurgeon's website. Mr. Spurgeion's passion is oil painting, and shares on his site how oil paints made by the old masters were made from linseed oil.

I figure if this is good enough for the old masters, it should also work for woodworking.

Enough blah-blah. Let's get to work:

First, instead of pressing my own flax seed, I ordered a liter of pure, quality raw linseed oil from El Barco, a local paint shop in Valencia.
Raw linseed oil.
Once it arrived, I went for a walk down to the beach. Joe Besch's video shows him adding sand, salt and marble dust to his mixture, but after reading Tad Spurgeon's notes, I am convinced that plain sea water and some sand from the beach should work great. These additives, from what I can figure, are to help purify the final oil similar to running water through a sand filter purifies the water.

I'm not sure, and if you would like to try it, I'm sure you'll have success using only tap water.
Believe it or not, you can buy sea water at a local grocer for 3.99/liter!
It was a bit stormy, but my trek was successful.
beach sand and seawater. And who-knows-what.
There was some dreck in the water, so I filtered it out with a paper towel.
Filtering the sea water.
Then I washed the sand by filling the jar with tap water, fixing the lid and shaking like crazy. I dumped the water out and repeated until I didn't feel like doing that any more.
The clean sand.
Likely, I used way too much sand. I think much less would have worked just as good. Once I dumped the liter of linseed oil into my two liter jar over the sand, I figured it was too late to take some out and we'll just have to see how it goes.
Next I dumped in my raw linseed oil.
Then, I topped off the jar with sea water. I would have liked a 50-50 mix of oil and water, but this is where we are. I think it should do something.
Oil on top, the water sank below it, and the sand is on the bottom.
Next I shook the jar like crazy until everything was mixed.
After the mixture was shaken. Not stirred.
Over the next couple of hours, I shook it up again. Joe Besch suggests three times.

Then, let it sit in the sun.
After an hour or so, you can start to see everything separating nicely.
After an hour.
And the last photo is where we are this morning, after about ten hours of rest.

If you are wondering what you are looking at, you can clearly see everything settling in layers. The bottom is the sand, and the little black bubble looking things above that is actually clear water. It is heavier than the oil so it sinks to the bottom.

The yellow band is a layer of fat we've just rendered out of the raw linseed oil. I suspect this is the stuff that prevents raw linseed oil from drying quickly.

The brown layer on top is the good stuff.
The next morning.
No earlier than tonight, and likely tomorrow, I'll extract the top layer using a baking syringe that I bought for the purpose. The idea is to get the pure stuff off the top without any of the unwanted stuff below.

I'll follow Joe Besch's advice and do this process again with my refined oil. I imagine after a couple times of this, I should get some pretty nice quality stuff.

The last step is to let it rest in the sun for some weeks or months, and the yellow color will evaporate away.

For my purposes, it probably doesn't need to be crystal clear, but it will be fun to see how far I can take this.

There is likely to be quite a bit less than one liter of oil after this process, but what I have should be good.

I'm not sure if this will be worth it, but it is fun to see if it will work.

Keep an eye on this blog in the future, I plan to post on the results of this experiment over time.


  1. Very interesting. I wonder if some of the dangers of BLO that we are familiar with (spontaneous combustion of rags) is caused by the metallic dryer they put in it, since it relies on a chemical reaction. If so this stuff should be safer??
    Be careful, but i would be curious to find out. And if so, why on earth dont they make that stuff around here?.

    Bob, who see a business opportunity, selling Atlantic ocean sea water ( i am surrounded by it :-)

    1. You could advertise your see water as half price, at only 1.99 per liter!

      I really don't know what the catalyst for BLO catching on fire is, and I don't really want to find out.

      Raw linseed oil is pretty easy to find. Getting good stuff is a little harder, but you can look at a health food store for "flax seed oil," it is the exact same thing.

    2. The spontaneous combustion isn't due to the catalyst, it is the oil itself polymerising that causes that.

  2. Fun experiment. But I will wait until you report the final results as a finish on wood ;-)

    1. Wise decision! You never know with what goes on around here!

  3. Hi Brian,
    stand oil can be had for relatively little money (depending on quantity) from Kremer Pigmente ( According to the MSDS it's absolutely clean (still combustible, though). Perhaps that would be a cheap (although much less enterprising) option.


    1. Thanks, Wolfgang. What is stand oil?

    2. Stand oil is linseed oil that has been polymerized (heated for a while, without any air). I'm not sure on the exact details, but I'm sure it would be extremely difficult to do at home.

      You can buy stand oil at many artist supply shops, it's used in painting.

  4. I'm working on the same thing right now. Though using kitty litter (per online recommendations) which works very well. Better than sand? I don't know but it seems to soak up the protein (?) slime/gunk. And -- lacking a household cat -- a bag should last some years.

    I have used the Dictum cold-bleached oil with some success as an interior paint medium, but I don't like it as a wood finish. Its thick consistency -- like cod-liver oil -- seems to prevent it from soaking deep into the wood and it leaves a very shiny surface, whereas a high-quality virgin oil just brings out the colour and grain and stays relatively neutral.

    I have left the oil in open glass containers in a sunny window sill -- and we will see in a couple of months or three.

    To put things in economical perspective, you should compare not to ordinary stand oil - but rather to this:

    At 226 euro/liter it should be worth the effort :-)

    Good luck! Looking forward to seeing how this works for you.


    1. See that, Robert? 1.99 for a liter of Atlantic sea water could be a good business plan! Haha!

      Thanks, Henrik! Kitty litter should indeed do a good job. I've used it before for oil spills in the garage. I like the Dictum stuff, but for a first coat I usually thin it out with something like the turpentine in the photo.

      This might be a dangerous rabbit hole to follow. Perhaps it would have been better if I had just kept using the cheap stuff from the Borg!


    2. That is of course the correct stuff to compare it to, but at € 9,16 per liter (and less if bought in bulk) it's cheap enough to try, I think. If it's too thick it can always be thinned down for better penetration.
      But, as I wrote in my reply to Brian, it might not help with the smell (or the color).

    3. I've had luck heating BLO before, too, for penetration. It's always scary, though.

  5. Great stuff, Brian. Your IG posts had me wondering at first if all that Spanish sun was a little strong for you :). Looking forward to seeing how this turns out.
    Btw, multiple references on the web (Bob Flexner and Wikipedia) indicate that all "drying oils" can lead to spontaneous combustion by their nature. If an oil will "dry" into a hardened surface (actually, crosslink or polymerize by oxidation), then it will probably generate heat in the process and can therefore start a fire under certain conditions (like a pile of rags that prevent the heat from dissipating).

    1. Haha! Thanks, Jeff! I suppose I was being a bit purposely vague on IG as that wasn't a real good platform to explain what I was trying to accomplish.

      Thanks also for the explanation about spontaneous combustion. I figured that was the case, but I've never started a fire that way, and hope I never do. When in doubt, I throw it in a bucket of water.

  6. It's actual boiled linseed oil (heated in the absence of air).
    It's premolymerized, and therefore dries relatively quickly on its own (without the need for any kind of dryer). It's used for traditional oil paints, among other things.
    I haven't yet used it, but I will, because the heavy metals in BLO make me uneasy somehow. Not sure if it helps with the smell, though.

    1. Thanks, Wolfgang! Indeed, that sounds promising. The smell is only there until it sets up and cures, which is normally a day or two. But, it's a day or two of me having to hear, "It stinks in here!"


  7. Always love me some woodworking experiments. and I learned a little about stand oil. Thanks!

    1. Me, too! I wonder why they don't just call it boiled linseed oil? Perhaps because the name is already used for something else.

    2. Stand oil appears to be an umbrella term for oils thickened by heating under absence of oxygen. Apparently wood oil has been used too. Whatever that might be...

  8. "I'm not sure if this will be worth it, but it is fun to see if it will work."
    I love that attitude. Great learning, great stuff!

    1. Thanks, Matt! The Borg stuff works just fine, but this is funner.

  9. Great experiment.
    I think that you should buy some water from Bob.
    I might also consider selling you some. That way you can compare if the result differs depending on the origin of the water used.
    But I don't think I can go as low as 3.99 per liter. Quality water from Scandinavia is pricey..


  10. Very interesting Brian. I hadn't heard of cold bleached linseed oil before. Anxious to see how it turns out.
    I switched from hardware store BLO to Tried and True a while back to specifically avoid the heavy metal driers.

    1. I'm pretty sure I will have something I could use in a couple days, but what's the point if we don't go overboard with overkill?

      Have you experienced any negative effects from BLO, or was your switch preventative?

    2. No negative effects. No sense taking the risk when there are alternatives.

  11. Great post. looking forward to learn about you results!

  12. This sounds like a great way to keep putting of projects. "No dear, I won't be able to get started on anything you want me to make because I am still making the finish!"

    1. Haha! I like it. "It's almost done. As soon as my linseed oil is ready!"

  13. Be careful...!!! That could give 'The Frau' some ideas... lol
    Great project for pursuit!

    1. Thanks, António! My problem is The Frau already has too many ideas! Haha.

      At least she doesn't read my blog. That's something.

  14. Hi Brian

    You should take a look at "Il Libro dell'Arte" by Cennino Cennini. It was written some time in the 15th century and describes all kinds of stuff related to the art of painting. The preparation of linseed oil, being one of them.

    Have a look here:
    "How Good and Perfect Oil is Made by Cooking in the Sun.
    Chapter LXXXXII
    When you have made this oil, some may be cooked in another way besides; and it is more perfect for painting, but for mordants it has to be cooked with fire. Take your linseed oil, and during the summer put it into a bronze or copper pan, or a basin, and keep it in the sun when August comes. If you keep it there until it is reduced to a half,[89] this will be most perfect for painting. And know that I have found it in Florence as good and choice as it could be. "

    You can fint the entire text here:

    The above quote is from "section 4".

    1. There is even a recipe for wood glue made from quick lime and cheese :-)

  15. Rottenstone (Tripoli) works really well in speeding up the drying time for "drying" oils too. I usually add a tablespoon of rottenstone per 0.5l of oil. Shake the mixture a couple of times and wait for rottenstone to settle to the bottom. I've done this most recently with cold-pressed raw hemp seed oil, and after this treatment the oil dries in about a day. Check out Stephen Shepherd's Full Chisel blog if you have a spare moment.

  16. Brian, I don't think I've seen any updates from you on this project. I've bee looking for a good solution for spoon finishes and was thinking this looked promising. Given the food grade nature of spoons, I try to choose cautiously. I currently use Flax seed oil (food grade raw linseed oil) but it takes a while to really cure... like forever. wondering how this played out.

    1. This stuff is awesome. I love it. Thanks for the reminder, I'll post something about it soon.

      Bob Flexner says pretty much any finish is food grade once it's cured, so I wouldn't worry too much. I use regular BLO on cutting boards, but spoons might be a little different.

      Stay tuned...