Wood Finishing Oil Comparison – Part 2

Last week, in Part 1 of my Wood Finishing Oils Comparison I covered my three top choices…Walnut Oil, Mineral Oil and Tried & True.  This week, in Part 2, I will cover the three oils I would not use for treating basswood prior to painting…Tung Oil, Linseed Oil and Danish Oil.  I mentioned my reasons for these choices two weeks ago in my December 3rd post.

Wood Finishing Oils

Tung Oil

Tung oil or China wood oil is a drying oil obtained by pressing the seed from the nut of the tung tree (Vernicia fordii).  Tung oil hardens upon exposure to air (through polymerization), and the resulting coating is transparent and has a deep, almost wet look.  Used mostly for finishing and protecting wood, after numerous coats, the finish can even look plastic-like.  Related drying oils include linseed, safflower, poppy, and soybean oils.  The oil and its use are believed to have originated in ancient China and appear in the writings of Confucius from about 400 BC.  Raw tung oil tends to dry to a fine, wrinkled finish; the English name for this is gas checking; this property was used to make wrinkle finishes, usually by adding excess cobalt drier.  To stop this, the oil is heated to gas-proof it, and most oils used for coating are gas-proofed, also known as “boiled”.

The name is often used by paint and varnish manufacturers as a generic name for any wood-finishing product that contains the real tung oil or provides a finish that resembles the finish obtained with tung oil.

Linseed Oil

Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (Linum usitatissimum).  The oil is obtained by pressing, sometimes followed by solvent extraction.  Linseed oil is a drying oil, meaning it can polymerize into a solid form.  Owing to its polymer-forming properties, linseed oil can be used on its own or blended with combinations of other oils, resins or solvents as an impregnator, drying oil finish or varnish in wood finishing, as a pigment binder in oil paints, as a plastcizer and hardener in putty, and in the manufacture of linoleum.

Linseed oil use has declined over the past several decades with increased availability of synthetic alkyd resins—which function similarly but resist yellowing.

Linseed oil is an edible oil in demand as a dietary supplement, as a source of α-Linolenic Acid , (an omega-3 fatty acid).  In parts of Europe, it is traditionally eaten with potatoes and quark. It is regarded as a delicacy due to its hearty taste and ability to improve the bland flavor of quark.

Drying properties

“Drying Oil”

Having a high content of di- and tri-unsaturated esters, linseed oil is particularly susceptible to polymerization reactions upon exposure to oxygen in air.  This polymerization, which is called “drying”, results in the rigidification of the material.  To prevent premature drying, linseed oil-based products (oil paints, putty) are stored in airtight containers.

Rags soaked with linseed oil stored pose fire hazard because they provide a large surface area for rapid oxidation. The oxidation of linseed oil is exothermic, which may lead to spontaneous combustion.  In 1991, One Meridian Plaza, a high rise in Philadelphia, was severely damaged in a fire, in which three firefighters perished, thought to be caused by rags soaked with linseed oil.

Wood finish

When used as a wood finish, linseed oil dries slowly and shrinks little upon hardening. Linseed oil does not cover the surface as varnish does, but soaks into the (visible and microscopic) pores, leaving a shiny but not glossy surface that shows off the grain of the wood.  A linseed oil finish is easily scratched, and easily repaired.  Only wax finishes are less protective.  Liquid water penetrates a linseed oil finish in mere minutes, and water vapor bypasses it almost completely.  Patio furniture treated with linseed oil may develop mildew.

Oiled wood may be yellowish and is likely to darken with age.

Because it fills the pores, linseed oil partially protects wood from denting by compression.

Linseed oil is a traditional finish for firearm stocks, though very fine finish may require months to obtain.  Several coats of linseed oil is the traditional protective coating for the raw willow wood of cricket bats; it is used so that the wood retains some moisture.  New cricket bats are coated with linseed oil and knocked-in to perfection so that they last longer.  Linseed oil is also often used by billiards or pool cue-makers for cue shafts, as a lubricant/protectant for wooden records, and used in place of epoxy to seal modern wooden surfboards.

Additionally, a luthier may use linseed oil when reconditioning a guitar, mandolin, or other stringed instruments’ fret board; lemon-scented mineral oil is commonly used for cleaning, then a light amount of linseed oil (or other drying oil) is applied to protect it from grime that might otherwise result in accelerated deterioration of the wood.

Danish Oil

Danish oil is a wood finishing oil, often made of tung oil or polymerized linseed oil.  Because there is no defined formulation, its composition varies among manufacturers.

Danish oil is a hard drying oil, meaning it can polymerize into a solid form when it reacts with oxygen in the atmosphere. It can provide a hard-wearing, often water-resistant satin finish, or serve as a primer on bare wood before applying paint or varnish.  It is a “long oil” finish, a mixture of oil and varnish, typically around one-third varnish and the rest oil.

Uses

When applied in coats over wood, Danish oil cures to a hard satin finish that resists liquid well. As the finished coating is not glossy or slippery, it is a suitable finish for items such as food utensils or tool handles, giving some additional water resistance and also leaves a dark finish to the wood. Special dyed grades are available if wood staining is also needed.

Application

Compared to varnish it is simple to apply, usually a course of three coats by brush or cloth with any excess being wiped off shortly after application.  The finish is left to dry for around 4-24 hours between coats, depending on the mixture being used and the wood being treated.  Danish oil provides a coverage of approx 12.5 sq. m/l (600 sq. ft./gallon).

Spontaneous combustion

Rags used for Danish oil, like those used for linseed oil, have some potential risk of spontaneous combustion and starting fires from exothermic oxidation, so it is best to dry rags flat before disposing of them, or else soak them in water.

The following information was taken directly off a can of Danish Oil:

Contains: Petroleum Distillates.  VAPOR HARMFUL.  May affect the brain or nervous system causing dizziness, headache or nausea.  Causes eye, skin, nose and throat irritation.

Keep away from heat, sparks and flame.  Prevent build-up of vapors by opening all windows and doors to achieve cross-ventilation.  Use only with adequate ventilation.

Carver’s Corner

The Carver’s Corner is a new section in Wood Chip Chatter where carvers can send in photos of the work for me to critique.  My idea is to help make you better carvers through my truthful opinions of your work, and my advice on where you can improve.  You will need to be able to accept constructive criticism without being offended.  It’s one of the best ways you can improve your carving skills because you will never become a better carver if you keep making the same mistakes over and over again.

Our first photos come from Nicky Foley who sent in two pictures of egg shaped Santas he carved…one he carved this month and a similar one he carved 3 years ago.

It’s easy to see the tremendous progress you’ve made in 3 years, Nicky.  You now have added hair texture to the mustache and beard, and the eyes and nose are carved much better.  In fact, the whole face is a vast improvement from your first one.  I like the larger, textured pom-pom on the hat but I would like to see a wider fur hat trim.  Most of us tend to make them too narrow.  The trim on Santa’s hat is actually quite large.  I would also try adding better defined texture to it next time.

Next is a photo of Nicky’s Simple Santa’s:

All three Santas are well done with little room for improvement.  I like the way you changed up the robe styles.  The fur hat trim is nice and wide on all three.  Perhaps make the pom-poms on top a little larger next time, and change the hat shapes a little.  Try leaning them to one side or the other, or flopping the top over all together.  You can even make the hat look like it’s twisted.  Also, try different color schemes on your Santas.  Just about any color scheme will work.

Next we have a photo of an old man with a cane carved by Todd Martin from Indiana.  Todd writes:

“Hi Bob,

Thanks for your offer to critique carvings. This is my most recent piece, and I’d appreciate any suggestions as far as areas where I could improve. I know I need to improve on the eyes for sure.

Best,

Todd”

Thank you, Todd, for sending your carving in for my critique.  From my first glance I could see you did a top-notch job on it.  From the photo it’s hard to tell how large the carving is but I’m estimating it’s about 4″ tall.  On a 4″ carving eyes are very difficult to do because there’s not a lot of room for detail.  You might want to try scaling up to a larger carving where you can play more with detail work.  I can see you already have a good handle on that.  I like how you did the shirt and the collar, but particularly like the hand on the cane.  The fingers are very well shaped and placed over the top of the cane and project an image of realism.  the left hand in the packet is well done too as I like how you bulged out the pocket to show that the hand is inside.  More practice is needed on faces (faces are hard to do, but larger projects will give you more room to experiment) although you’ve done a good job of creating the look of an old man.  Overall, a terrific job.

Questions & Comments

We have a notable question from Leonard this week about how to get good looking facets on your wood carvings.  Leonard writes:

“Hello Bob, just wanted to ask a question about Ricks simple Santa carving. Really great looking carving, and I was wondering how to get those really good looking small facets in the carving, looks really tidy. I have tried it and for some reason just can’t get the look as in Ricks carving. Any tips on how to achieve this look? Thanks, Leonard”

A very good question, Leonard.  Facets are the result of your knife cuts (probably an obvious answer there), but to get really good facets you want to make bold, clean cuts, and you don’t want to round off the edges of those cuts.  Bold cuts are deep cuts.  Many carvers are afraid to carve too deep into the wood and this is a mistake.  More often than not there is plenty of available wood to carve deeper which allows for better looking facets.

If you are referring to the cuts in the mustache and beard, those cuts are usually made with a 1/16″ (1.5mm) or 1/8″ (3mm) V-tool.

I hope I’ve answered your question, Leonard.

Announcements

I will be taking a much needed break over the Christmas and New Year holidays so there will be no Wood Chip Chatter blog posts on Friday, Dec. 24th and Friday Dec. 31st.  Wood Chip Chatter will return on Friday, Jan. 7th with more handy woodcarving information to help improve your knowledge and skills in the craft we all love.

At this time I want to wish all my loyal readers and carving friends a very Blessed and Merry Christmas, and a Healthy and Happy New Year!

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

Zoom:  3104603575

SCHEDULE:

12/18 – 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’s start the New Year off right!  Don’t forget to submit your comments, questions and photos for our return on January 7th!

Show us what you carved over the holidays!

Keep a sharp edge and keep on carvin’!