Boiled Linseed Oil

[seafoam]

Over the last few years I have noticed an increase in the number of people using boiled linseed oil (BLO) as a finish. I seem to recall reading many years ago that this finish darkens considerably with age. Don't ask me where I read this, but I'm sure I didn't make it up.

So, is it true that it darkens, and what has given rise to it's recent popularity as a finish?

Does anyone have anything they finished with BLO more than ten years ago and can comment on it's appearance now.

 

[Jake Debski]

Over the last few years I have noticed an increase in the number of people using boiled linseed oil (BLO) as a finish. I seem to recall reading many years ago that this finish darkens considerably with age. Don't ask me where I read this, but I'm sure I didn't make it up.

So, is it true that it darkens, and what has given rise to it's recent popularity as a finish?

Does anyone have anything they finished with BLO more than ten years ago and can comment on it's appearance now.

A late sage member of our turning chapter,who was also an antique dealer, preached that BLO darkened with age. He had several examples of old pieces that he and others had finished with BLO and were very dark. Wood naturally darkens(oxidizes) with age also. Unfinished wood darkens more rapidly than one with finish on it. Combine this natural effect with a finish that darkens you can guess the result. But I wonder how long, in years, before this darkening becomes detrimental to the looks of the piece? I'll probably not live long enough to see it.

 

[Jred]

A late sage member of our turning chapter,who was also an antique dealer, preached that BLO darkened with age. He had several examples of old pieces that he and others had finished with BLO and were very dark. Wood naturally darkens(oxidizes) with age also. Unfinished wood darkens more rapidly than one with finish on it. Combine this natural effect with a finish that darkens you can guess the result. But I wonder how long, in years, before this darkening becomes detrimental to the looks of the piece? I'll probably not live long enough to see it.

I have tiger maple chairs that are a bit over 100 years old. When having them appraised we were told that they were most likely finished with BLO and some sort of varnish. They look great. The maple is not the light blonbe maple we are used to seeing but a rich light brown. The figure stands out beautifully and they have a rich patina. Many of the oil finishes out there currently incorporate BLO. It can be mixed with pure Tung oil for a good middle ground. Pure Tung oil I'm told will not darken but will give you many of the good properties of BLO like "popping" the figure in curly maple or other woods.

 

[Tom Lewis]

I have a mesquite bowl that I finished with 2/3 linseed oil and 1/3 shellack. I made this bowl 37 years ago and it hasn't changed a bit.

 

[Joe Herrmann]

I pre-finish all of my flat work with a coat of BLO thinned 2:1 with paint thinner. I think it makes the grain pop and allows me to correct any defects prior to applying a built up finish. Once dry (a day to a week) I follow up with two coats of polyurethane. I've been doing this for over 35 years and have not noticed any appreciable darkening of the finish.

Joe

 

[Jake Debski]

I have tiger maple chairs that are a bit over 100 years old. When having them appraised we were told that they were most likely finished with BLO and some sort of varnish. They look great............................

The combination you mention, BLO and varnish is the basis for the original "Danish Oil." You can still buy it under the " Tried and True" brand. I have used it and as I said previously, I doubt I'll be around long enough to see if it darkens enough to be detrimental.

 

[dkulze]

I'm one of those folks who started with BLO and moved to straight eurythane pretty quickly. Up until pretty recently, BLO was the way to go because the eurythane oils did not exist. Now, however, I'd be surprised if you couldn't find a eurythane oil that cured harder, faster, or gave better depth and "pop" to a piece than BLO.

Another nice thing is that eurythane doesn't sponteneously combust if your rag is wadded up.

Just an opinion.

dietrich

 

[Brujo]

BLO does indeed darken with age

home depot linseed oil strait from the can was my prefered finish for wood long before I started turning. I have noticed that it does darken many different woods.

Most of the pieces I am thinking of are 7-10 years old and many have darkened or yellowed. In particular canary wood, maple, and cocobola. The canary wood and maple turn a funney yellow color (like old ivory), cocobola has darkened. Some purple heart and paduk are also considerable darker as well but I have no older examples of those types of wood that I have finished with anything other than linseed so I have nothing to compare to. Not to mention they darken a lot an their own anyway.

I have maple, canary, and cocobola that where finished with minwax wipe on paste. They all are considerable lighter in color than the same woods that where finished with linseed. Other woods I've used may darken as well but I have not noticed the color being what I would consider ugly so it has not been an issue. In particular I've been happy with the way poplar, oak, walnut, wenge, and particularly lace wood have turned out using linseed.

I now only use tung oil. I have not used it long enough to see how it stands up to the test of time, but I like the quality of the finish better than linseed.

Just my $.02

-Justin

 

[Ed_McDonnell]

eurythane ??? Urethane???

Are eurythane oil and urethane oil the same thing?

Ed

 

[Richard Baker]

And is that the same as polyurethane varnish??

Have used a coat of BLO to enhance the contrast in spalted hackberry, followed by finish coats of clear lacquer. Unknown if the pieces will darken significantly long term.

 

[dkulze]

Mea Culpa! Mea Culpa!

Spelling was never my long soot.

And Poly Varnish is different from the oils. It's a surface finish (I think).

Dietrich

 

[Ed_McDonnell]

Dietrich - I thought that Urethane Oils were 50-70% mineral spirits with various resins (oil modified polyurethane, alkyd, proprietary??) making up the majority of the balance.

That doesn't sound much different than a thinned out wiping varnish???

What brand of urethane oil do you use and do you know what is in it?

Ed

 

[Jake Debski]

Mea Culpa! Mea Culpa!

Spelling was never my long soot.

And Poly Varnish is different from the oils. It's a surface finish (I think).

Dietrich

Polyurethane Varnish is a surface film finish. Urethane oil is harder to identify because of "propitiatory oils" listed on most cans. Minwax, General finishes, and others have in their stain lines a "Natural." This is just the uncolored oil that is used as a carrier for their color pigments. This oil is thin and penetrates into the wood. It dries overnight and builds somewhat, and buffs nicely, not unlike Danish Oil. Salad Bowl Finish, lists urethane resins and propitiatory resins on the can. General Finishes' Seal-A-Cell has almost the same ingredients. They are all urethane based but I have not been able to find pure urethane oil. It might not exist in pure form, or react properly without additives.

 

[Richard Baker]

Thanks Jake. Sounds like the "oil" is at least similar to what I get by diluting the varnish 50% for the first few coats. It does penetrate a bit, and takes several many coats to ultimately fill the grain and form a level surface film. The "interior" varnish is very slightly more clear than the "exterior", but the latter contains UV absorber or blocker which helps prevent long term darkening of some woods (padauk, for example).

 

[dkulze]

Am I correct in thinking that the urethane and polyurethane oils are synthetically based, vs. the polymerizing natural oils such as tung and BLO?

Dietrich

P.S.(pretty sure that varnish, by definition, is resinous solids disolved in solvents vs. polymerizing oils with solvent thinners)

 

[MichaelMouse]

The urethane is a resin included to harden the cured oil film. Other resins are used, and other oils as well as linseed. Basic varnish is a resin, an oil and a solvent to spread it out. Less solids, less surface build.

 

[dkulze]

Aaaaaah. Learn something new every day.

Okay, maybe every other day.

Dietrich