Boiled linseed oil

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Forum topic by nate22 posted 12-01-2014 11:54 PM 1420 views 0 times favorited 13 replies Add to Favorites Watch
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453 posts in 2292 days

12-01-2014 11:54 PM

I see a quit of few people use boiled linseed oil. What is the difference between that and polyurithane? Is it better for wood especially for wood that will be outside? Should I just keep using polyurethane or try boiled linseed oil.

-- Gracie's wooden signs. Middlebury, In.

13 replies so far

View JAAune's profile


1614 posts in 1734 days

#1 posted 12-02-2014 12:04 AM

Jeff Jewitt has a good primer on different finish types. The answer to your specific question is a little more than halfway down the page. I recommend reading the whole article.

Choosing a Finish

-- See my work at and

View crank49's profile


3979 posts in 2388 days

#2 posted 12-02-2014 04:49 AM

Oil and poly are two entirely different things.
Poly is a finish that forms a shell on top of the wood.
Oils are products that soak into the wood and then dry, sort of.
Just can’t compare the two.
But the above linked reference is very good and worth the time to read.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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Rick M.

7677 posts in 1797 days

#3 posted 12-02-2014 05:08 AM

Oils provide very little protection and for the most part, are just for looks. For example something that will not be handled roughly, or is largely decorative, can be finished with oil & wax, many people really like the look. Oil is also great for tool handles as varnishes and lacquer cause blisters. I also use oils to fortify old, dried out, wood. The oil adds weight back into the wood and combats brittleness. Think of oils and waxes like Chapstick, it won’t protect your lips from sunburn or physical damage, but will help keep the skin moist and flexible. (yes, I know there are lip balms that protect against sunburn but I’m talking plain old Chapstick)


View bobro's profile


308 posts in 728 days

#4 posted 12-02-2014 06:15 AM

Linseed oil is also used for outdoor applications- picnic benches, railings, decks and so on. Even raw linseed is used, which takes a very long time to dry and as crank49 described it, dries “sort of”. Retorators have cut into medieval furniture and found the oil deep inside the wood still wet. So it’s as Rick M. described but I wouldn’t say it’s just for looks- it’s very protective, but only in certain ways.

My little shop is protected from wind, rain and direct sunlight, but temperature and humidity wise it’s pretty much outdoors. So I soaked my workbench in raw linseed oil.

“Danish oil” is a good compromise. It’s mostly linseed oil, has driers, soaks in, but with many applications slowly builds a thin protective film as well.

-- Lao Ma: You are so full of anger and hatred. Xena: Everybody's gotta be full of something.

View mudflap4869's profile


1128 posts in 876 days

#5 posted 12-02-2014 08:05 AM

Wooden tool handles will absorb water, repeated cycles causes checking in the wood. Oil penetrates the wood and prevents water absorption, thus it prevents checking. Grandpa treated all of his tools at least once a year with BLO. All his tool handles survived several decades of regular use, and were still like new when he died. He never left a dirty or dull tool at the end of the day. His barn workshop was allways as clean as grandmas house. He began his woodworking career in 1918, and continued until he died of a stroke while digging a root cellar with a pick and shovel in 1964, at the age of 69. Tough old Welchman to the end. And still my hero!

-- Still trying to master kindling making

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Fred Hargis

3838 posts in 1910 days

#6 posted 12-02-2014 12:24 PM

Just a minor point: the typical reference to “polyurethane” is really meant to indicate varnish ( in an oil based finish), most if it is made with urethane resins, hence the nickname. But it’s also used for a few other things (some makers call their waterborne “polyurethane”) so using that as a name for a finish can get some confusing replies.

-- Our village hasn't lost it's idiot, he was elected to congress.

View OSU55's profile


1039 posts in 1407 days

#7 posted 12-02-2014 01:21 PM

Polyurethane soaks into the wood about as much as BLO and the danish oils, and can build a film if desired. My “oil finish” consists of poly thinned 50%, wiped or brushed on until the wood stops absorbing, then wiped off. Additional coats are added until I get the film thickness desired. This creates the same look and feel as BLO but is faster and more protective than BLO, and equivalent and cheaper than the danish oil stuff. IMO keep using poly. I do use a water emulsion BLO product for staining. Target Coatings WR4000 is a waterborne stain base that looks like BLO but can be tinted with Transtint dyes. I have not had great luck with solvent based dyes. Transtint dyes are much easier to work with but don’t mix with mineral spirit based stains or finishes (there is now an additive for this).

View Wildwood's profile


1848 posts in 1552 days

#8 posted 12-02-2014 04:08 PM

Most of my experience with finishing wood for outdoors comes from making whirligigs and bird houses. I never intended to do routine maintenance, like sanding and refinishing. Seriously doubt my customer did any routing maintenance other than bringing in whirligigs before a hurricane. Did get a lot of repeat business! Wood selection determined whether used exterior latex paint or no finish at all. Never put a finish on cedar or cypress, pine, poplar & oak got painted. Had great sources for free wood back then.

I have used both BLO & wax emulsion water sealing products on wood clothes line post & porch swings. Water sealing products work okay if done once or twice annually. BLO does nothing to protect wood from the elements and will darken or turn wood black.

If want a clear finish stay with exterior poly or varnish that has UV protection. I would prefer a spar varnish over poly. Definitely would not use BLO, feel it is unnecessary.

-- Bill

View lndfilwiz's profile


88 posts in 1018 days

#9 posted 12-02-2014 04:46 PM

I used BLO to treat a walnut stock for my muzzle loader. I made a diluted mix of 4 parts kerosene and 1 part BLO to start my project. I saturated the stock with the diluted BLO and set it to dry under my wood stove. I usually let it sit for 48 hours then sanded it with very fine sand paper.

I kept increasing the amount of BLO in my mixture by adding more BLO and less Kerosene and increasing the grit of the sandpaper. I finally used 2 coats 100% BLO and 00 steel wool to finish the stock. I have had many comments on how nice it looked. This was done in the early 70’ when all you could get was a kit to build your muzzle loader.

-- Smile, it makes people wander what you are up to.

View buildingmonkey's profile


242 posts in 965 days

#10 posted 12-03-2014 01:06 AM

Years ago a woodworking magazine published an article describing a formula designed to protect outdoor wood. It came from the forest products laboratory. The formula was a quart of BLO , think a cup of melted parafin, and the rest paint thinner for a total of one gallon. I tried it on a solid wood garage door, looked good. The parafin seemed to coat the surface as kind of a finish. You just heat the parafin up till it is liquid, and pour it into the paint thinner, oil base not the water based stuff, and add the BLO, stir and brush or spray it on.

-- Jim from Kansas

View Picklehead's profile


991 posts in 1347 days

#11 posted 12-03-2014 01:17 AM

Where’s Clint Searl? Seems he might have an opinion on BLO.

-- You've got to be smarter than the tree.

View Joel_B's profile


292 posts in 798 days

#12 posted 12-03-2014 02:05 AM

I am planning to use BLO and then Poly on Cherry. My impression is BLO adds color and brings out the grain, otherwise I would just use poly. Is this right? I also see that BLO is usually followed by shellac before putting on the poly:

The BLO adds depth to the finish, shellac served as additional depth plus a bit of a build coat, and the wipe on poly provides the high sheen.

-- Joel, Encinitas, CA

View Rick M.'s profile

Rick M.

7677 posts in 1797 days

#13 posted 12-03-2014 02:41 AM

I am planning to use BLO and then Poly on Cherry. My impression is BLO adds color and brings out the grain, otherwise I would just use poly. Is this right? I also see that BLO is usually followed by shellac before putting on the poly:

The BLO adds depth to the finish, shellac served as additional depth plus a bit of a build coat, and the wipe on poly provides the high sheen.

- Joel_B

Shellac is an all purpose sealer compatible with all finishes. It seals in the oil so you don’t have to wait weeks or months for it to dry before applying waterbase poly. Fun fact, you don’t need to wait for the oil to dry before applying shellac. Regular (waxed) shellac will actually buff out to a much higher shine than varnish/poly. The only time I use varnish is for tables because the tops take more abuse than other things and even then I’ve only used it on about half the tables I’ve built. I have a couple shellac end tables that have been going strong for over a decade. A drunk relative spilled whisky once and made a mess of the finish but it only took me about 15 minutes to fix.


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