Full Chisel Blog

May 14, 2011

Blown Oil or how to ‘boil’ raw linseed oil with air

This is one of the more interesting things that you can do with raw linseed oil.  Why you may ask?  It turns raw linseed oil into ‘boiled’ linseed oil by beginning the polymerization process by introducing oxygen.  And I am not making this stuff up.

This is a half a gallon of raw linseed oil that I poured into a glass gallon container.  There was some sediment that started to come out, so I stopped and still have some left in the can.  This I will strain and do something else with and I will save what I strain out [the foots] and make some putty.

During the historic period traditional methods would have been used.  Lacking a water wheel and the steam engine isn’t running yet, I bought an inexpensive aquarium air pump and some tubing to go through the process.  I put some small holes in the end of the tubing and crimped the end.  Seems to be working fine.  The pump is a lit annoying [I’ll put it in the back room] but the bubbling of the oil is pleasant.

I will let it work for a while and monitor the condition of the oil.  At the end of the process this oil will be turned into a drying oil without adding any chemical driers.  After a couple of days the bubbles are behaving differently, not as big and more uniform in size.

Of course all of this will be covered in Shellac, Linseed Oil, & Paint – Traditional 19th Century Woodwork Finishes which will hit the press soon [should go to the printer Monday].  It will be available from Tools for Working Wood and if people want a personally inscribed copy they can contact me.



  1. This is totally fascinating. I would love to buy your book (is it possible to send it to Reykjavik, Iceland)?

    How long does this process take? And how do you know when the oil has become “boiled”.

    Comment by Heida — January 5, 2012 @ 5:53 pm

  2. Heida,

    Welcome and I can send the book to Iceland. It costs more [about $10.00 more]for postage, send me an email at stephen@fullchisel.com

    I boiled [bubbled] the oil for 8 hours or so a day for a month. It lightens in color during the process.


    Comment by Stephen Shepherd — January 6, 2012 @ 9:27 am

  3. 6.Hello and thank you.—I invite you to visit my oil painting website for artists/You can see my results in using an air pump to polymerize flax oil [ linseed oil]. I am happy to see your personal efforts as an on site investigator researcher of this phenomenon – HOW MODERN AIR PUMP CAN ACCELERATE POLYMERIZATION OF FLAX OIL. The reason your oil is turbid then clear is because of the oil you used is raw crude oil containing MUCILAGE. Mucilage is microscopic and invisible to the unaided human eye, but is fully 100% in suspension in the oil. Cool temperatures makes the oil become turbid…warm temperatures make the oil transparent. The Old Masters learned through centuries of observation that ‘unclean’ oil [ meaning the mucilage was not removed] would over many years, become brown. This caused their oil paintings to become dark and brown. They learned how to remove the mucilage SAFELY. The key ingredient is ETHANOL..or–as they found, by using a strong spirit liquor such as brandy, whisky etc. the ratio is 1 part strong liquor to 5 parts raw flax oil. Flax oil is sold at health food stores–but WARNING: Almost ALL of these health stores add ANTI-OXIDANTS !![ vitamin E & C, Rosemary, Tocopherols, POlypherols, etc]–this of course will STOP THE DRYING of the oil –since the oil- will only dry by exposure to oxygen. BARLEANS is the oil I buy and use for many years–but–do not buy they oil that is for pets nor their highest lignan oil. READ the fine print label.Barleans grows, and harvests and presses their own oil. Many other companys are only distributors. READ more on my website. Please write- I woud like to speak with you. I first heard of the AIR PUMP METHOD about 2 years ago-but I did not test it until 2012. IT WORKS! ..sorry–it will not “SEED” other raw oils. THats a fallacy. All that does is create a ‘ co-poly’ oil. KEY to making a fast drying artists oil are 2 things= ONE= first you must remove the mucilage TWO. then use an air pump to introduce oxygen 24/7. WARNING: stop at 12 to 15 days of 24/7 use of the air pump—too much polymerization causes heavy wrinkling of the oil when made into oil paint as it dries. See my book and DVDS on my site–THank you-and CONGRATULATIONS for researching, investigating, sharing. !!-Louis Velasquez http://www.calcitesunoil.com, velapress@aol.com

    Comment by Louis Velasquez — October 9, 2012 @ 7:39 am

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