"One Coat" Flax Seed Oil Finish ó Is it for Real?

Finishers consider what a new "one coat" wood finish formula based on flax seed oil might actually contain, then move on to a complex technical discussion of the chemical nature of natural oil finishes. August 27, 2012

Does anyone have opinions on Rubio Monocoat? I bought some for stair treads and wondering if I should use it on my solid wood furniture. It looks great, but I'd like to know how it wears.

Forum Responses
(Finishing Forum)
From contributor Y:
MSDS say it contains 10% aliphatic hydrocarbons (term used to designate things like mineral spirits) and it's been odorized to conceal the smell of the A hydrocarbons. It may be VOC free as to what the governing bodies allow, but it by no means is "just oil".

Educated guess Ė itís a form of alkyd finish made from oils. Can you finish your furniture with it? Sure, but will it be any better than or maybe not as good as a top notch alkyd varnish? Itís a much better build and protection with rock hard. Price-wise and life of the coating wise, you'd be better off with Behlen's rock hard four hour alkyd varnish. A proven decades-old varnish!

From contributor H:
You read this one right, this is the hottest thing on the eco/chemical free market. It is pitched as a one coat, chemical free flax seed oil all natural finish. Correct about the government regulation about the deodorized mineral spirits (below 10% you can list it a zero VOC). It sure looks to me like it is 12th century linseed oil and wax finish which was great technology then but it still smells and turns black with age!

I have been approached twice with new furniture that was finished with this product where the customer was hypersensitive to the smell of the linseed oil. One we washed with thinner and shellacked and waxed. The other we rinsed with thinner and applied pure tung oil. Neither smell or turn black and is far more durable.

From the original questioner:

I talked to the company and all they would tell me about the ingredients is that flax seed oil was one of the ingredients, among other things. There is some sort of wax in it too. A similar product I used is Osmo's Polyx oil, but I found it develops rings when wet, so that one's out. I want a good oil for walnut chairs I build for restaurants. I've had good luck with tung, but it was a little time consuming. I have many is one of the busiest restaurants in San Francisco and they still look great five years later.

Does linseed oil turn black? Also, I started to wonder about tung oil causing nut allergies more than linseed oil. Is this silly? I just want a finish that takes little time and is easy to repair, which Rubio claims to do. I'm not doing table tops, so I don't feel a thick film finish is as important. Am I really asking for the impossible? All the oiled pieces in my home still look great many years on. Any suggestions on how I should perform my own tests in various products?

From contributor H:
Tung oil has been lining tuna cans for years. Years ago there was some fuzzy association with it and Epstine Bar virus, do not think it ever went anywhere. Unless you go out of your way, BAAQMD will not let you use off the shelf tung oil at least not in anything more than a one quart can. I am working in the same places you are and it is not legal to use tung oil that is cut with mineral spirits. I have one project that requires tung oil, so I order gallons of pure tung oil and cut it with citrus solvent.

Tung oil is better than linseed oil, but neither are suitable for commercial use (unless you get a contract to re-coat them every few months). Your oil finish may sound romantic, quick and easy but in the long term will be a consent maintenance issue and these places do not do maintenance.

From the original questioner:
If Monocoat works as they claim it would save me a lot of time. It takes an average of three coats of tung oil and a coat of wax to get the look of one coat of Monocoat. I'm not saying itís better or worse, just asking for opinions from those who have used it. I do worry about nut allergies, which are on the rise, though I have difficulty imagining how a chair would cause a problem. Those with the most severe allergies would likely not go to any restaurant.

I mentioned flax seed oil because I asked a guy at Rubio if it was polymerized linseed oil and he would only say flax seed oil was an ingredient. He kind of refused to use the word linseed. I'm going to try tung some more and in a new way and I'll report back my findings.

Contributor H - would love to outsource my finishing, but everyone local charges more for a clearcoat than the average person wants to pay for a chair, even in quantities over 50. Frankly, my clients and I like the look of oiled walnut, even when it isn't perfectly maintained. Scratched film finishes always look rough and are far harder to repair.

From contributor Y:
With the added info I went back and looked at the application PDF, which gives a few more clues in using it as to what I think it still may be and why. First off as I said it is not just an oil, be it flax or other. I don't necessarily believe someone who sells a product to know whatís really in a coating. When secrets are meant to be kept, disinformation runs rampant.

That said, even if it is flax and not tung or oiticica or cashew nut oil (good suspect there), dehydrated Castor oil, or any of the other commercial coatings oils used for damn near a century now, it is not just the oil that's creating the surface shown in the pictures of the application PDF.

The next indicator is the wax you speak of. With that info I had somewhat of a change of mind as to what it could be but very uncertain, meaning if it's an oil that naturally contains wax like rosewood oil, then that could also be suspect. Be it that or others though it is still not what is enabling the surface to acquire a one coat shine such as shown in the pictures.

So letís look at the PDF for application. In the third paragraph we find this: Thoroughly remove all the dust from the floor before you start applying the oil. This new technology enables the oil to make a molecular connection within 15 seconds with the wood surface by means of a reaction. If there is dust, the oil will connect with the dust, which will become a microscopical paste upon the surface when the oil is spread. The Oil will be connected with the dust instead of the wood fibers.

Here we see that two terms are used, molecular connection and reaction, both meaning the same thing in reality. For the reader, for a "reaction" to occur, at least two differing molecules of substance have to be involved for it to take place. A molecule of H2O2 (hydrogen peroxide) for example and a molecule phosphoric acid or sodium hydroxide will cause a reaction, normally one of heat and foaming. That is why acid catalyzed coatings should not be used over a bleached or oxidized surfaces unless it is well neutralized and tested first, and even then there can be later long term problems.

So with that info along with this next bit: "The oil will become connected with the dust and not the wood itself". We can see if it is a true reaction, or if it is a mild reaction. So what is the finish reacting with? Most logically it would be the "tannin" present in all woods to one degree or another. The others - the cellulose itself, or lignin (very doubtful).

If it's a tannin reaction there are too many chemicals to try to know for sure which one. If itís a cellulose reaction most likely it would be a reagent such as Schweitzers which is mainly copper sulfate and potassium hydrate in distilled water or de-ionized. At full strength, it is capable of totally dissolving the cellulose and leaving behind just the lignin. In very diluted amounts it would be capable of softening the cellulose to allow better penetration of the oil or other liquids used. Your first baby step in to chemical reaction.

Next it states if the dust is not removed, it will create a paste or slurry microscopically, meaning the "reaction" will be with the dust not the wood surface. This would indicate that whatever the reaction is the wood must be virtually chemically clean in order for it to properly take place, thus the need for the pre-cleaner.

Now we come to the unspoken resin, ďwhy a resinĒ? Well that comes from this bit of PDF info. "It converts the wood fiber." Converts it into what? Is it no longer cellulose or lignin? Of course it is, even under microscopy it would still look/act/and visually be the same. So what do they mean by convert? Think of this, what is conversion varnish or cat lacquers etc.? It is a combination of resins being acted upon by acids to cause the plastic materials to polymerize and eventually harden/dry/cure/etc.

In this scenario, it's being used to replace the obvious use of a resin with some mystical chemistry terms not familiar with the reader or user. The other dead giveaway of there being a resin is when they talk of repairing and how the material will only absorb into the wood where the wood is unsealed due to damage but wonít adhere anywhere else. Also you should wipe it off after 30 seconds or so on the undamaged portions that are still coated with the product.

That makes me wonder - as it should everyone, what will happen if it is not wiped off the undamaged areas? Will it just peel off over time or can you dis-adhere it yourself and peel the whole area up? Odds are incredibly in favor you could, just like if you were to apply a coat of poly over an un-sanded coat of poly and let dry. If you don't know what happens then run a simple test, apply a coat of poly (gloss) on a piece of glass, let dry 36 hours (but before you do put a piece of duct tape on the glass about three inches), and leave three or more inches hanging off an edge first. Then when you apply another fresh coat of poly, allow to dry the same, now pull on the tape towards the glass, what happens? So in my estimation it still is a mix of oil/wax/possible reagent/ and resin, alkyd/poly/would be my guesses as of now.

From the original questioner:
I'm glad you're doing a trial. One of the things about it that I discussed with the Rubio guy was application for furniture. He said all I had to do was wipe on, wait ten minutes, then wipe off. On the floor directions, there was an elaborate buffing schedule, which he said was for making floor application easier, since that is their main clientele. I'm not sure if the positive results I received were because of the buffing. I asked if there was some benefit like the heat from friction, but he told me no.

From contributor H:
Aside from catalyzation into the cellular structure of the wood, we are basically dealing with the durability of "The Resin Structure" and concentration of that structure left once the solvent (vehicle) has evaporated or cross linked.

Durability is a very fuzzy description of how much and what type of damage a "finish" can absorb before it needs to be repaired. With basic durability factors such as: resistance to moisture, surface scratching, adhesion, decomposition from oils, acids, and every days usage as a guide to durability, we should be able to come up with a basic range of " hardness" of most common finishes. Linseed oils, tung oils would be at the bottom end as would ester resins and isocyanates on the upper end. This is not to say that oils do not have their advantages and epoxies and 2pak's are the ultimate finishes. Once you ask and know what is in the finishes that you are using and understand the appropriateness of that finish/resin structure to your specific usage you can make an intelligent choice of what to use and why you are using it.

The difference between linseed oil and flax oil is how the oil is extracted from the flax seed. Food grade flax oil is a press extraction system while linseed oil is a solvent extraction system. This product seems to make several "Snake oil" references in their literature, such as being zero V.O.C.'s and the "One Coat Only" process, they also maintain that they use only flax oil. This could also be a legal or a marketing definition, I do not know. Some plant based oils are very unstable and will go rancid with oxidation over time.

From contributor Y:

Present methods (up to the last decade or so that I know of) call for refinement of the oils by both acid and alkali types of those most oft used, tung/LO/BLO/ Oitlcica/ perilla/dehydrated castor oil/chia/hempseed/poppy/and safflower-sunflower-walnut (being the least used). The higher unsaturated ones used most by us B-LO/tung, are what I will talk of as to the processing of present time to make them stable and without rancidity as to other less or differently refined oils.

In both cases the "break" often termed the mucilaginous material, by the aforementioned processes in the oil is removed, by further reaction of chemical agents (usually sulfuric acid or caustic soda) then after a bleaching treatment, (charcoal and fullers earth,) it is put into refrigeration to remove any and all solid fats and or waxes, thus creating a non-rancid end product. Various other small treatments can be and are used in individual cases as to the oils end uses and demands.

Other secondary oils and least use may have the same done, but normally not unless the purchaser ask for it to be done. Many I mention are in general used for cooking purposes or other and the fats are left in so as to keep both taste and lightness intact.

What we deal with is the four or five main oils that have iodine numbers (showing the amount of saturation or unsaturation of the oil) in the upper areas of more than 150, tung and linseed being high - tung 192, linseed also, oiticica - 190. The linseed has a lower refractive index than tung and is why I use it the most. I rarely use LO any more accept for color glazing and occasional oil staining, never as a first coat on wood. LO - RI = 1.48, Tung = 1.515, very close to the r/ index of woods!

If used as a first application on woods thinned down to 5% or less (95 parts pure gum turps to 5 parts tung) will give the best visual as to depth and other. Why turps? It also has a closer RI number than most other solvents/diluents normally used in the average shop.