Is Linseed Oil Toxic?
Written by:
Maia James
We’ve written before about the toxins household furniture releases into our homes (When Furniture Attacks), but mostly have focused on upholstered furniture (check our Safe Sofa Guide for Good Stuff brands).
Toxins in Wooden Furniture
Finding nontoxic wooden furniture can actually be just as challenging as finding a nontoxic sofa, even though you don’t have to worry about flame retardants. Choosing only solid wood pieces is a great start (lots of “wooden” furniture is really made of particle board or plywood which is glued together with formaldehyde-releasing adhesives), but the finishes can be another big problem.
One area of confusion for lots of folks is around linseed oil. Is this truly a nontoxic wood finish, or just Sneaky Stuff?
Here’s the deal with linseed:
Based on our research, we feel that pure, 100% linseed oil poses little, if any, toxic threat to human health, even though it does emit an odor as it dries. Material Data Safety Sheets (MSDS) on linseed oil tell us that it is non-toxic, and various other sources confirm this.]
Beware of “boiled linseed oil.”
The confusion around linseed oil arrives when with “boiled linseed oil,” which is what’s found in most stores/home-centers is confused with 100% linseed oil.
Basically, there are three types of linseed oil, two of which are non-toxic.
1) Raw linseed oil is, in fact, flax seed oil. It takes a long time to dry but is entirely non-toxic.
2) The polymerized version is true “boiled” linseed oil, sometimes called “stand oil”. Stand oil is generated by heating linseed oil near 300 °C for a few days in the complete absence of air. Under these conditions, a is highly viscous product results, which provides exceptionally uniform coatings that “dry” to more elastic coatings than linseed oil itself. It also dries much more quickly (although still more slowly than toxic, commonly-used polyurethanes.) This true boiled linseed oil is also non-toxic.
3) The “boiled linseed oil” you can buy in most stores is actually mostly raw linseed oil, but with plasticizers, hardeners, and heavy metals added to make it act like true boiled oil, without the time and effort it takes to actually boil it; in other words, it’s cheap. Folks who are concerned about the toxicity of linseed oil are likely thinking of this type.
We’ve identified two sources for good linseed oil: Heritage Natural Finishes and Earthpaint.
Stay sane,
Maia, Founder & CEO
Note: This article contains affiliate links or sponsored content, which means that if you make a purchase, we may earn a commission. We only recommend products that meet our strict standards for non-toxicity and that we use (or want to use!) ourselves. Thank you so much for supporting the brands that make Good Stuff!
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17 responses to “Is Linseed Oil Toxic?”
I purchased 2 natural wood microwave carts from IKEA . The directions say to oil them before using. What can I use that is safe for animals and at the same time safe for humans since food will be sitting on them. My son who is a furniture refinisher said to get boiled linseed oil. Can you tell me the ingredients in boiled linseed oil and if it’s toxic and safe to use around food?
You dont answer if it is toxic at all. You just say that cheap boiled linseed oil is what people are likely to be thinking of. Are they thinking its toxic and correct or not? Thank you,
Not toxic. Period. BLO is probably the safest, most environmentally friendly finish of any product on the market. Others, such as Tung oil and Watco (which is based on BLO but with other additives), are far more of a concern.
As always, do not take something from me — or this non-scientific site — as gospel. You have the research capability at your fingertips to get the real info. That said, will you understand it (did the author here, even, understand it?)?
1. Do not substitute dietary flaxseed oil for boiled linseed oil (BLO) or raw linseed oil. The latter two are finishes. But flaxseed oil goes rancid. You don’t want your wood finishes going rancid.
2. People are worried about the “siccatives” added to BLO because of the words “heavy metal.” They think “nuclear reactor” when they hear them. Yes, cobalt is a heavy metal. But so is the iron in the axhead whose hickory handle you’re putting BLO on. Are you afraid of iron?
a) First of all, these two things (cobalt and manganese) are in your diet — just as iron is!
b) They are essential to your health. Without them — same as farmers do for their animals — you’d have to take them as nutritional supplements or get shots to get them *into* your body. (The thing that makes vitamin B12 work is the cobalt in it). Any excess amount is flushed out.
c) *Can* you take so much that it’s toxic? Yes. Almost everything you eat has a point of consumption that is “toxic.” But how in the world would you expose yourself to a significant amount to be toxic? You can drink BLO — if you don’t mind diarrhea and stomach aches. (Don’t drink BLO). Plus, there’s different ways to create the cobalt and manganese salt compounds. BLO does NOT contain the dietary formulations of these salts. Still, you’d have to concentrate them and ingest them as tablets or something. Then, yep, you’ll probably get sick — could even die — just the same as if you o.d. on Vitamins A, C, D (especially D), K…. et al. You can even die from drinking too much water. But an obstacle remains, how? How would you drink that much? How would you expose yourself excessively enough for cobalt and manganese to be toxic? They don’t accumulate in your body. Excess amounts are naturally flushed out in your urine and excreted with your feces — same as *any* salt is. You’re a human being, coolest mammal on the planet because your body holds exactly what it needs, flushes the excess out (other animals, like cows, etc., need a constant resupply). Bottom line, what’s potentially toxic is not likely toxic in any likely scenario. It’s why the SDS for BLO specifically says no known adverse health effects. The ONLY warning is the same two warnings put on *any* oil finish: 1) Risk of spontaneous combustion if left on crumpled rags in poorly ventilated areas; 2) If you atomize it (make an aerosol of it, mist it), wear a mask. Vapors won’t hurt you but breathing in an oil mist might. Because it’s a drying oil. And you’re essentially coating your respiratory system and lungs with the same substance you’re spraying onto wood to create a hard durable finish. It’s not smart to coat your lungs with something intended to dry into a hard durable finish.
d) Still afraid of cobalt and manganese salt? Want to minimize your exposure? Stop eating meat, fish and dairy…and stop drinking beer. All these have a ton more cobalt in them than BLO. And to avoid manganese, stop eating salads. In fact, don’t touch things in your home. Most clear glass items (windows, bottles, glasses, serving platters) have cobalt in them to make them clear glass. As do a lot of ceramic finishes. … Just…. stop walking around in your environment, don’t eat, drink or touch anything. Most of it has more cobalt in it that the BLO did.
e) They are only present, in trace amounts, as ionically neutral metals (hence, “salt” — cobalt and manganese “salts”). That’s what makes them drying agents.
Don’t take my word for it. Fact check these things. NO ONE wants the responsibility entailed in pronouncing something is “safe” for you. All I’m saying is, stop listening to Chicken Little. Take each thing I said here and look it up. Am I right?
And THEN…. if you’re still concerned — don’t use it. I can’t stand listening to tards talk about the “toxicity of BLO” or the “heavy metals in it.” But bottom line, you don’t *have* to use it. Just use raw linseed oil instead. No additives. Absolutely, perfectly fine — and no reason to look up anything, because there’s nothing else in it. It will just take much longer to dry, period. But you get exactly the same, lustrous, glass-smooth, non-blister-raising finish as with BLO. Just takes longer. But it’s the same stuff.
Great explanation, thank you so much! I will be buying flaxseed oil meant for ingestion, for wood finishing!
Yeah, no. Don’t want to do that, as flaxseed oil goes rancid. Just use raw linseed oil.
Thanks for the good info.
I’m now going to read the material safety data sheet before buying finishes
hi, does anyone know of a brand that IS nontoxic?
Yes. All linseed oil and boiled linseed oil finishes are nontoxic. The only ones that are toxic are those with additional additives or other formulations. Watco, for instance, based on boiled linseed oil, carries warnings about toxicity. Which means, you *can* make a product containing BLO that also has toxins. But itself, no. — And as with all things, you need to look this up for yourself. Do not ask others to relieve you of concern about your health. No one wants that responsibility. (So don’t take my word for it. Read the manufacturer’s SDS for the specific product and formulation).
what about Refined linseed oil?thx
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