Wood Finishing Oil Comparison – Part 1

Last week we had an enlightening discussion on the difference in the oils used to treat basswood before painting.  I explained the difference in the properties of six oils:  Walnut Oil, Mineral Oil, Tried & True, Tung Oil, Danish Oil and Linseed Oil.  This week I want to provide more in depth information on those oils in order to give you a better understanding of each and to help you make your own decision on which one to use.  I’ll start with Part 1 this week, and cover Walnut Oil, Mineral Oil and Tried & True.  These are the only three that I will recommend, in that order.

Wood Finishing Oils

Walnut Oil

Walnut oil is oil extracted from walnuts, Juglana regia.  The oil contains polyunsaturated fatty acids, monosaturated fatty acids, and saturated fats.

Composition

Walnut oil is composed largely of polyunsaturated fatty acids (72% of total fats), particularly alpha-linolenic acid (14%) and linoleic acid (58%), oleic acid (13%), and saturated fats (9%).

Culinary use

Walnut oil is edible and is generally used less than other oils in food preparation, often due to high pricing. It is light-colored and delicate in flavor and scent, with a nutty quality.  Although chefs sometimes use walnut oil for pan-frying, most avoid walnut oil for high-temperature cooking because heating tends to reduce the oil’s flavor and produce a slight bitterness.  Walnut oil is preferred in cold dishes such as salad dressings.

Cold-pressed walnut oil is typically more expensive due to the loss of a higher percentage of the oil.  Refined walnut oil is mechanically pressed and saturated with solvent to extract the highest percentage of oil available in the nut meat.  The solvents are subsequently eliminated by heating the mixture to around 400 °F (200 °C).  Both methods produce food-grade culinary oils.  Walnut oil, like all nut, seed and vegetable oils can turn rancid.

Over 99% of walnut oil sold in the US is produced in California.

Artistic use

Walnut oil was one of the most important oils used by Renaissance painters.  Its short drying time and lack of yellow tint make it a good oil paint base thinner and brush cleaner.

Some woodworkers favor walnut oil as a finish for implements that will come in contact with food, such as wooden bowls, because of its safety.  Rancidity is not an issue because walnut oil dries when applied to wood in a thin coating.  People who mix oil and wax to formulate wood finishes value walnut oil as an ingredient because of the edibility of both ingredients.  The oil typically is combined with beeswax in a mixture of 1/3 oil to 2/3 beeswax.

Mineral Oil

Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils.

The name ‘mineral oil’ by itself is imprecise, having been used for many specific oils over the past few centuries.  Other names, similarly imprecise, include ‘white oil’, ‘paraffin oil’, ‘liquid paraffin’ (a highly refined medical grade), paraffinum liquidum (Latin), and ‘liquid petroleum’. Baby Oil is a perfumed mineral oil.

Most often, mineral oil is a liquid by-product of refining crude oil to make gasoline and other petroleum by-products.  This type of mineral oil is a transparent, colorless oil, composed mainly of alkanes and cycloalkanes, related to petroleum jelly.  It has a density of around 0.8–0.87 g/cm³ (0.029–0.031 lb/cu in).

Toxicology

The World Health Organization classifies untreated or mildly treated mineral oils as group 1 carcinogens to humans, meaning known to be carcinogenic to humans; highly refined oils are classified as group 3, meaning that they are not suspected to be carcinogenic, but available information is not sufficient to classify them as harmless.

The UK Food Standards Agency (FSA) carried out a risk assessment on the migration of components from printing inks used on carton-board packaging—including mineral oils—into food in 2011, based on the findings of a survey conducted in the same year.  The FSA did not identify any specific food safety concerns due to inks.

People can be exposed to mineral oil mist in the workplace through inhalation, skin contact, or eye contact.  In the United States, the Occupational Safety and Health Administration (OSHA) has set the legal limit for mineral oil mist exposure in the workplace as 5 mg/m³ (0.0022 g/cu ft) over an 8-hour workday, the National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 5 mg/m³ (0.0022 g/cu ft) over an 8-hour workday, with a previous limit of 10 mg/m³ (0.0044 g/cu ft) for short-term exposure rescinded according to the 2019 Guide to Occupational Exposure Values compiled by the ACGIH.  Levels of 2,500 mg/m³ (1.1 g/cu ft) and higher are indicated as immediately dangerous to life and health.  However, current toxicological data does not contain any evidence of irreversible health effects due to short-term exposure at any level; the current value of 2,500 milligrams per cubic meter (1.1 g/cu ft) is indicated as being arbitrary.

Applications

Laxative, personal lubricant, baby oil. cell culture, veterinary uses, cosmetics, mechanical, electrical and industrial uses, and food uses.

 Other uses

Mineral oil’s ubiquity has led to its use in some niche applications as well:

• Mineral oil is used for treating and preserving wooden butcher block counter tops.
• It is commonly used to create a wear effect on new clay poker chips, which can otherwise be accomplished only through prolonged use.  Either the chips are placed in mineral oil for a short time, or the oil is applied to each chip then rubbed off. This removes any chalky residue left over from manufacture, and also improve the look and feel of the chips.
• Mineral oil is used as the principal fuel in some types of gel-type scented candles.
• It is used for cooling, such as in the liquid submersion cooling of components in some custom-built computers.
• Veterinarian-grade mineral oil is inexpensive, and is frequently used by amateur radio operators as coolant in RF dummy loads, as mineral oil is typically used as the insulating and cooling fluid in large electrical equipment such as transformers.
• Mineral oil is used as a brake fluid in some cars, such as Citroen models with hydrodynamic suspension, and bicycle disc brakes.
• Mineral oil is burned in specialized machines (both manufactured and home-made) to produce a thick white smoke that is then blown into automotive evaporative emissions (EVAP) systems to find leaks.
• It is used for polishing alabaster in stonework and lubricating and cleaning pocket knives or food handling tools that use an open bearing, thus needing periodic lubrication.  Light mineral oil (paraffinum perliquidum) is used as a honing oil when sharpening edge tools (such as chisels) on abrasive oil stones. Mineral oil USP or light mineral oil can be used as an anti-rust agent for blades.
• It is an inexpensive alternative for storing reactive metals, such as lithium and sodium.
• Horticultural oil is often made of a combination of mineral oil and detergent. It is sprayed on plants to control scale, aphid, and other pest populations by suffocation.
• Before the widespread adoption of thermocyclers with heated lids, it was common practice to use mineral oil to overlay polymerase chain reactions in biotechnology to prevent loss of water during heating cycles. It is often used to suspend crystals for use in X-ray crystallography.
• It is used as a transparent collision material for reactions in particle physics, as in the MiniBooNE neutrino oscillation experiment.
• As a relatively low heat combustible with no flavor or odor, mineral oil can be used in fire breathing and firedancing for entertainment, but there is a risk of injury.
• Paraffin oil is commonly used to fill Galileo thermometers.  Due to paraffin oil’s freezing temperature being lower than that of water (approx. 24 °F (−4 °C)), this makes them less susceptible to freezing during shipment or when stored in a cold environment.

Tried & True (Traditional Danish Oil)

Most finishes today contain petroleum distillates, solvents or heavy metal drier additives. This Danish oil doesn’t. Pure polymerized linseed oil with no additives, it strictly adheres to the standards established by the FDA (Food and Drug Administration) and qualifies as non-toxic and safe for food-contact surfaces in both its uncured and cured (wet and dry) states. An ideal choice for kitchenware and furniture, it penetrates deeply into wood surfaces and builds to a durable, water-resistant satin sheen.

Made using traditional 18th-century production techniques, it is a high-yield finish, providing coverage of at least 75 square feet per 16 fl oz/473ml.

The oil is applied sparingly to the surface, allowed to penetrate for 5 minutes and then wiped clean and buffed dry. Subsequent coats can be applied in as little as 24 hours though allowing 2 to 3 days between coats will speed curing of the finish. Good protection is achieved with 2 to 3 coats. Buff surfaces occasionally to maintain sheen.

A simple, environmentally-friendly finishing solution available in 16 fl oz/473ml and 32 fl oz/946ml containers.

Part 2 will continue next week with Tung Oil, Linseed Oil and Danish Oil; three products which I don’t recommend for use as a treatment for basswood prior to painting, and you will see why.

Readers’ Comments

Our first comment this week comes from Bill Douglas from Pataskala, Ohio along with a photo of the really amazing pins he carved from my Simple Snowman ornament pattern.  Bill says:

“Hi Bob:

I wanted to thank you for your article and pattern for the Simple Snowman Ornament in the Woodcarving Illustrated Winter 2021 issue.

I took a little liberty with your pattern and reduced it to make blouse pins for a couple of friends.  Hope you like the photo?  Plan on adding a couple of Holly Leaves to the red hat after spraying it.

Thanks for helping me be a better carver!”

Hi Bill…Thanks for writing!  I always love to hear from my readers.  What a great idea, making blouse pins from my Simple Snowman ornaments!  I never thought of that, and yours look terrific!  I would love to see it again after you add the holly leaves to the red hat.

Next we have some questions from Rick about Walnut Oil.  Rick writes:

“Hi Bob,

I know you were going to talk more about oils this week, so wanted to throw in a few questions I had if you aren’t already covering these. Is the Walnut oil from the grocery store any different than from brands like Mahoney’s or Lee Valley?  How long do you let the oil dry on the wood before painting?  And finally, does the oil go bad after a while and does it have to be refrigerated.

Thanks

Rick”

All good questions, Rick, and I’ll try to answer them in order.  First, there is no difference in the Walnut Oil from the grocery store compared to Mahoney’s or Lee Valley.  In fact, the one I use is Mahoney’s.  Walnut Oil dries slowly but I usually like to paint after allowing the oil to sit for only about 15-30 minutes.  And finally, Walnut Oil does not go bad or turn rancid, and does not need to be refrigerated.

We also have a photo of a Simple Santa Rick carved from my pattern:

That’s an excellent Santa, Rick!  One of the best ones I’ve seen.  The cuts are crisp and the overall work is very clean.  I hope you will send another photo once you have it finished.

Our next comment comes in the form of a letter from Nicky Foley from Ireland.  In his letter Nicky makes some good comments and suggestions, and asks a couple of excellent questions:

“Hi Bob
Thank you for what you are doing being from Ireland we do not have much in the way of local woodcarving clubs the way we have woodturning clubs. I also love joining the weekly calls on Saturday evenings with the international association of woodcarvers what Thom and Blake have done bringing woodcarving to the world has definitely helped me with my carving skills.

I liked the article about the choices of oils, I have used BLO for a while now and never thought to try mineral oil (which I use all of the time in my woodturning). I have tested it against BLO and I can say that I see no difference in the paint quality and I normally paint directly after applying the oil to my carvings. Game changer for me with no smell, easier to clean off, cheaper and no fear of combustion. My bottle stopper was oiled using mineral oil before painting.

I like Bobs suggestion (not you Bob) about getting feedback on carvings, we do this in woodturning where we get an experienced woodturner to critic the work of beginners, this helped me in progressing from a beginner to an intermediate woodturner and to even get the confidence in demonstrating in front of others, but you have to be willing to except what is being said about your piece that you have spent hours in creating and you yourself think is great.

Your tip about increasing the size of your carvings is exactly how I do mine and its funny how last year this is what I done to your simple Santa. We have just put up our Christmas decorations and it was nice to see some of my first carvings and to see the progression through the years, so it’s a good idea to sign and date all of your carvings.

Could you cover simple facial measurements in one of articles please, I have recently started with facial carvings and find it hard to get it right all of the times, eyes too big, too far apart, nose is to wide or too long and I won’t mention ears :).

Keep up the great work, we might not always reply but we are always reading 😉

Regards,
Nicky Foley”

Thank you for your complimentary words about my work and Wood Chip Chatter, Nicky!  The International Association of Woodcarvers is an excellent platform where carvers can learn from other carvers and I try to support them whenever I can.

I’m glad I was able to steer you in the right direction with the BLO/Mineral Spirits debate. 

The comments on getting feedback on your carvings is well noted.  It doesn’t do a carver any good to tell him his carving is fantastic when it really isn’t.  That carver would be better served if you gave him constructive ideas on where you think he can improve.

In fact, beginning next week I will be adding a new section to Wood Chip Chatter called “Carvers Corner” where readers can send in photos of your carvings for my constructive criticism.  I will critique the carving and offer my honest constructive advice on where you may have gone wrong or how you can do things differently next time.  Hopefully it will help you become better carvers.  So let’s see if we can get some carving photos this week to get things started!

It’s funny you should ask about facial measurements, Nicky.  I was planning to post something on that very subject in the near future.  Look for it right after the new year.

Announcements

The International Association of Woodcarvers has upcoming Zoom meetings on the following Saturdays at 3PM with special guests.  Check them out…

Zoom:  3104603575

SCHEDULE:

12/11 – Dale Green

12/18 – Eric Owens

12/25 – Christmas

1/1 – New Year

Upcoming guests for 2022 are Dave Francis, Bob Hershey and Kevin Applegate.  Dates to be announced.

INTERNATIONAL ASSOCIATION OF WOODCARVERS

COME JOIN US!!!

Let the chips fly!  Tell your wood carving friends and spread the word about Wood Chip Chatter, and don’t forget to click the ‘Comment’ button at the bottom of the page to send in your questions and comments so we can keep Wood Chip Chatter active and keep the conversations going! 

And remember, we need your photos!  I’m sure you all have some terrific carvings to share, and photos of your carvings will help to liven up the blog’s appearance and make it more interesting.  Perhaps we can start a carvers photo section!  Email your photos to carverbobk@woodchipchatter.com

Keep a sharp edge and keep on carvin’!

Whoever coined the phrase ‘Quiet as a mouse’ has never stepped on one.