Posted by alin23 6 days ago
I prefer to keep the original color of the wood I sell, so lower temperatures are better for me, but I like the look of toasted wood as well.
My problem with just oil is that the finish is very matte, hence the wax and resin complication I'm going through in the article. But matte is also a look that people look for so there's no problem in that, it's just my personal preference and style that's different.
I honestly do not know because while I have read that specifically boiled linseed oil does cure to be safe it was not clear to me whether it was safe for skin contact or fully food safe and food safe isn’t the same thing as safe for e.g. stirring pasta as it boils or stirring food that is frying in oil.
Also...most linseed coatings will mold if they're not kept dry. If you'd like to avoid that, look for purified linseed oil -- it's regular linseed oil, but the proteins that mold feeds on have been removed. If you really want to go crazy, look for the stuff made from food grade oil.
Highly-refined mineral oil is food-safe.
https://en.wikipedia.org/wiki/Mineral_oil#Food_preparation
Why even use wood if you’re going to cover it in a layer of clear plastic?
I find it amusing that those who will use wood or "natural" (petroleum is also naturally occurring...) products for some sort of weird misguided eco-virtue-signaling, inevitably end up needing to basically reinvent the chemistry of finding an inert, durable material that brought us modern plastics. All these drying oils create a layer of polymerised material, which can be classed as plastic anyway. Waxes, regardless of source, attribute their properties to long hydrocarbon chains, just like polyethylene.
I'm of the same opinion as you, drying oil polymers are still plastic, it's just that their method of curing makes them look better on wood, most likely because of the very thin layer that remains at the surface, but also because of the polymer surface texture.
Every epoxy resin, even the more penetrant ones, end up looking like plastic on wood, not sure how else to describe it.
But in terms of chemistry, food safety and how inert they are, they are indistinguishable.
I'm also aware mineral oil is food safe, I was trying to say that it will leak into the hot food and not stay in the wood fibers, which renders the finish useless after just one use.
I came at your article from a slightly different perspective. Rubio monocoat is quite expensive, especially if you’re trying to run a business selling products coated in it. You’re probably already aware, but I think base Rubio is essentially oil + carnauba + a small amount of paraffin. I make large pieces of furniture, and finishing with Rubio can go through multiple cans! So making my own finish has become a priority. That’s not even accounting for Blacktail Studio coating too.
For example we can create hydrocarbons using solar/wind energy and that is still "renewable" even though hydrocarbons are involved. They are merely the medium of energy storage.
The only reason why they are not used now is that the current price of fossil oil is significantly lower.
There is research to develop more efficient methods for the synthesis of hydrocarbons, based on the electrolytic reduction of carbon dioxide, but their progress is slow, in good part because such critical research is funded much less than frivolous research, such as that for AGI.
Irrelevant for spoon making, too few of those ;)
No, that is absolutely not the case.
And the reason is exactly the finish. Metal and plastic spoons, forks, lids, etc. are nice and smooth and don't get in your way. Cheaply made wood or cardboards ones are rough and tacky.
Of course you could argue that from an environmental standpoint, that's not a bug but a feature: now I'm using even less disposable stuff (first, no plastic because it's been replaced by other stuff; and second also the replacements because I hate using them).
My spoons and cups feel more like warm textured ceramic. They are sanded to a high 600 grit, water popped multiple times to make sure the grain doesn't raise and the texture stays smooth, and finished with drying oils as you see in the article to keep the surface highly hydrophobic.
I really can't describe it in words, but everyone I know who tried eating with my wooden spoons and drank from my coffee cups, was pleasantly surprised of the feeling.
That's why most of my sales happen in person at local craft markets, because there, people can take the cup into their hand, they can feel the smoothness, and they can ask about the same things you are worried about.
All I can recommend is find a spoon carver in your area, or one that ships there, and try a hand carved eating spoon. I'm not saying it's better than metal, ceramic or plastic, it's just a different experience that some people enjoy.
Later.
https://www.finewoodworking.com/2024/10/10/the-best-food-saf...
(...no links provided). Really? "Studies show" you don't need to use soap to rinse off the wooden cutting board you just chopped up raw chicken on? Without a citation there I'm extremely skeptical
https://www.researchgate.net/publication/369940932_Wood_Cutt...
But, yes, if you just soap a board and rinse after cutting raw chicken on it, and then immediately (i.e. without allowing drying overnight) put on e.g. raw vegetables, and then e.g. throw those raw veggies in the fridge to be consumed / eaten hours or days later, then indeed the simple washing may not in general be enough, or may not be practically much different than using lots of very hot running water. E.g. some epidemiological studies fail to find washing habits predict outbreaks (https://academic.oup.com/jaoac/article-abstract/89/2/538/565...).
But the conclusion to draw from this is not to skip the soap, but, rather, that the drying is often a more crucial part of good washing than the particular washing method.
> The current scientific consensus as far as I can see is that wooden is less safe than plastic or glass as it results in more biofilm formation, and more absorption than plastic or glass.
It is trivial to search Google Scholar for this topic and see that, in most cases, there are no meaningful practical differences for bacterial safety between wood vs. plastic boards, and, if anything, the anti-microbial properties and self-healing nature of wood boards probably in general do make them safer than plastic boards, which quickly get permanent gouges that harbor more bacteria.
Wood cutting boards can also be rapidly sterilized in a microwave, which is more convenient for cooking dishes with multiple ingredients than e.g. the dishwasher for plastic boards, or dilute bleach, for either. And in fact the whole argument is moot precisely because the real clear factor is obviously proper washing and sterilizing. Given the astounding lack of evidence for plastic superiority, and the clear evidence that cutting boards produce non-trivial micro-plastics [4], it is still quite reasonable to prefer wood overall, at least in the home.
References:
[1] Aviat, F., Gerhards, C., Rodriguez-Jerez, J.-j., Michel, V., Bayon, I.L., Ismail, R. and Federighi, M. (2016), Microbial Safety of Wood in Contact with Food: A Review. COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, 15: 491-505. https://doi.org/10.1111/1541-4337.12199
[2] Dean O Cliver, Cutting Boards in Salmonella Cross-Contamination, Journal of AOAC INTERNATIONAL, Volume 89, Issue 2, 1 March 2006, Pages 538–542, https://doi.org/10.1093/jaoac/89.2.538
[3] Boursillon D, Riethmüller V (2007), "The safety of wooden cutting boards: Remobilization of bacteria from pine, beech, and polyethylene". British Food Journal, Vol. 109 No. 4 pp. 315–322, doi: https://doi.org/10.1108/00070700710736561
[4] Özuluğ, O., Şarlak, İ., Sarcan, F., … Yürekli, Ö. D. (2025). Health Risks and Environmental Threats of the Food Prepared on Plastic Cutting Boards. Turkish Journal of Bioscience and Collections, 9(2), 65-75. https://doi.org/10.26650/tjbc.1745221
All the reasons he gives for wooden boards being worse are literally directly opposite to the truth (plastic gouges more easily because wood self-heals; the absorbent properties of wood is actually a plus that promotes drying and kills bacteria). It is shocking how horribly uninformed that post is.
As a first bad sign, though this paper is published in 2018, the authors fail to cite any of the numerous prior studies showing no differences or superior behavior of wood relative to plastic, indicating some pretty glaring biases right at the outset. Moving on:
> "Formation and quantification of biofilm. To verify if all 10 strains were biofilm producers, we used plastic, wood, and glass circles with a diameter of 1 cm. These materials were washed, dried, and autoclaved in a Petri dish. Next, with sterilized tweezers, each circle was placed on the bottom of a well in a 24-well plate. Plastic and wood circles were obtained by cutting samples from commercially sold boards. [...] The Salmonella strains were incubated in Luria-Bertani (LB) broth at 35°C/24 h. Next, the culture was diluted [...]. Aliquots of 300 lL were distributed in triplicate into the wells, and the plates were incubated at 35°C/96h."
Obviously no cutting board is ever in such conditions, and even still, their Table 1 shows in fact that there is NO significant difference (4 plastic vs 6 wood) in samples in biofilm growth. At no point do they ever show meaningful growth of biofilm on a washed cutting board allowed to dry.
They also don't mention if these are new cutting boards, which invalidates the whole thing, since the problem is that plastic cutting boards gouge and then don't wash properly. Every decent study looks at used or gouged boards as well, otherwise they don't reflect real-world usage.
> "Each Salmonella strain was incubated in BHI broth at 35°C/24 h and diluted [...], and 1 mL was uniformly spread on a chicken breast surface, previously thawed, and Salmonella-free. Next, each [cutting board] surface was contaminated by rubbing with the contaminated chicken for 30s. This step was performed in duplicate to assure the transfer of Salmonella from the cutting surface to the cucumber because a cotton swab would capture most cells on the first rub (item a, below mentioned), leading to an undetectable count in the vegetable due to the low number of residual cells (item b, below mentioned)"
You can judge if this is realistic or not. Also, if a simple swab is removing so much cells that they couldn't detect anything in the vegetables later, how could washing not possibly be removing the same? This is an extremely suspicious comment in general. Let's see:
> "the contaminated boards were washed before they were exposed to the cucumber. The washing was performed with hot running water for 10s, vigorously scrubbed with a new sponge moistened with neutral liquid detergent, rinsed in hot running water, and dried"
Surely not, but it sounds like they are washing with a dry sponge moistened only with detergent? Dried for how long? Because we already know it needs to be hours in all cases, this is nothing new. Was the sponge abrasive or a soft one? You need an abrasive and lots of hot water, not a dry, soft sponge "moistened" only with pure detergent, and ten seconds of scrubbing if you want washing to do anything at all, especially smeared chicken breast. Smeared chicken always needs a two-phase wash, once with a harsh abrasive tool (scouring pad or brush) with soap, then a rinse, and then again with a normal sponge, or you obviously have chicken bits left behind. Nothing about the procedure sounds adequate.
> "As expected, when the surfaces were unwashed after contact with the contaminated poultry, all strains were recovered. Regarding the washed surfaces, the wooden one showed the highest positivity in recovery of pathogens, occurring in 9 out of 10 tested strains. Fewer positive samples were observed on plastic and glass surfaces, 3 of 10 and 1 of 10, respectively. According to the Cochran test, both surfaces differed significantly from wood, showing them to be the easier materials to be sanitized, in the absence of biofilm ( p < 0.05)."
The inexact and high p-value means this is exceedingly weak evidence (actually not significant if you account for multiple comparisons), and what is a "positive sample" in terms of actual counts is not defined, which is also highly suspect. Also why are we using such a weird statistical test? Real studies will have log reductions or actual counts (e.g. [3] - which also looks to find plastic to be worse, from what I can read). Very p-hacky.
"All samples of cucumbers displayed the presence of Salmonella Enteritidis, regardless of the cutting surface material unwashed [sic]. After washing, the wooden cutting surface showed the highest transfer of bacterial cells to cucumber, followed by plastic and glass surfaces, which again were shown to be the more hygienic materials, differing statistically from wood. On the contrary, all cucumber samples were contaminated with Salmonella Enteritidis, even after washing the cutting surface in the presence of biofilm [emphasis mine]"
So in one case (salmonella without biofilm) wood looks worse with marginal significance, but in all cases where the salmonella is biofilm-producing, it doesn't matter what the board is made of. Pretty unconvincing.
So, yeah, nope. Use plastic or wood, just clean properly.
[1] Dantas, S. T., Rossi, B. F., Bonsaglia, E. C., Castilho, I. G., Hernandes, R. T., Fernandes, A., & Rall, V. L. (2018). Cross-contamination and biofilm formation by Salmonella enterica serovar Enteritidis on various cutting boards. Foodborne Pathogens and Disease, 15(2), 81-85. https://scholar.google.ca/scholar?output=instlink&q=info:H9T...
[2] Bischoff, A., Alter, T., & Schoenknecht, A. (2025). Hygienic Evaluation of Wooden Cutting Boards: Microbiological Parameters. Journal of food protection, 88(9), 100576. https://doi.org/10.1016/j.jfp.2025.100576
[3] Pegueros-Valencia, C. A., Lucero-Mejía, J. E., Hernández-Iturriaga, M., & Godínez-Oviedo, A. (2025). Assessing Salmonella enterica biofilm formation in frequent scenarios of chicken handling in domestic kitchen environments. Food microbiology, 132, 104849. https://doi.org/10.1016/j.fm.2025.104849
This is very confused.
First, all wood finishes you can buy are food-safe once cured. They aren't allowed to be sold otherwise, at least in the US/Europe/et al.
If you are using them once heated, this is not always as true (and regulations vary a bit), but if we are talking about food prep/salad/you name it, they are all safe.
Heat wise, if we are talking about using it in boiling water to stir something, most finishes would be fine from a safety standpoint (not all can withstand this though).
As a general rule of thumb, if you aren't heating the wood above 200F, you aren't really going to get a finishes to release toxic fumes[1]
Second, as for solvents - smell is not everything. The HDI he mentions rubio having will not smell like anything until the concentration is way way way way too high. If you can smell it, you are in trouble. HDI is also much more dangerous than most solvents[2].
The oil is also a solvent.
Solvents are just things that you can dissolve something else in.
If they want to avoid certain types of solvents for some reason, that should be about safety or something, and if they want to evaluate that, smell is probably the wrong evaluation criteria.
To give one example of solvent elimination with a purpose, let's take VOC's, which are about pollution[3].
Avoiding VOC solvents makes for cleaner air, but again, VOC compliant/exempt/etc solvents vary wildly in whether they are safer for people or not than non-VOC exempt solvents.
If you are trying instead to avoid human-toxic solvents, you would choose a different set, etc.
[1] There are so many finishes with so many different properties that i can't 100% guarantee this, but non-professional stuff you can buy at a woodworking store or a big box store is going to be fine
[2] The lack of smell of isocyanate's is main the reason you can get service life indicating respirator catridges from 3m/et al - otherwise you would not be able to determine if your cartridge is working or not, since you would not smell it when spray finishing/etc until the concentration is way too high, even if your cartridge is spent. Sane folks just use supplied air anyway, rather than risk it at all.
[3] not safety to humans, though often highly confused with being safer.
> If you are using them once heated, this is not always as true (and regulations vary a bit), but if we are talking about food prep/salad/you name it, they are all safe.
If you are exposing it to cooking temps, and want something very natural, i'd just use an oil and not a "hardwax". The wax part is not going to buy anything.
"hardwax" is just a made up term that means nothing for real, some of them are harder waxes (carnauba), some of them are not. In any case, none of them will survive heat, because the wax won't.
Standard BLO is not food-safe and is sold everywhere.
So if you are using that as a wood finish, you get what you get?
Also most of it is still food safe when cured anyway, it just does't always fully cure and it's hard to tell when it's cured.
But once the polymerization/etc has actually finished, there are no oxidizing agents or driers or ... left.
If you look at the law suits that lead to it being labeled the way it is, it's not about food safe when cured, it's about the inability to tell when curing actually finished, and final curing taking a very long time.
- most finishes are indeed "food safe after curing", I'm aware of that. How they look on wood, how they perform when being dipped in hot soup or when drinking hot liquids from them, that's harder to assess without buying cans of finish that I have to store forever if I don't like them.
- HDI doesn't smell indeed, I never said it did. In fact two-component hardwax oils would have been perfect if it was easier to mix and apply in small quantities. Unfortunately for the few drops of oil I need on a spoon, it's too messy
- I'm talking about solvents in the definition that most consumers know about them: volatile solvents that usually smell strongly. I used low-VOC solvent-based finishes and they still smell. Organic components aren't the only smelly things in solvents, and I simply can't stand them anymore, that's all. It's not all about the dangers, it's for my own comfort.
If you can point me to a solvent-based hardwax oil that smells of only the oils and waxes inside, I'll buy it in a pinch and forget about melting waxes in my microwave. Google search doesn't help here, I need to hear it from someone with experience
For small one-time projects it's generally fine to just use a brand new filter and toss it afterwards. Hobbyists painting a car panel aren't using supplied air.
People often put the cartridges in a plastic (or sometimes mylar if they are advanced) bag to save money, and change them when they can smell stuff. This is a bad plan with isocyanate.
Auto finishes are moving towards iso-free 2k urethanes anyway. (wood will get there, but tends to lag)
Most of the toxic fumes/etc come from breaking molecular bonds. There is a minimum temperature, and below that temperature, it just doesn't really occur.
If it starts happening, regardless of whether there is visible smoke/vapor, the finish will quite obviously visibly degrade. Either it will flake off, slough off, or you will just be able to remove it with your fingernail.
Take polyurethanes - they mostly start releasing toxic fumes at 300-400F just about the second they get to that temperature. Below that, nothing.
This is because that's the temperature at which the isocyanate bonds start to break, even if there is no flame. You will not see smoke or vapor. But it will become essentially non-protective and flake off or otherwise visibly degrade.
At a much higher temperature (700-800F) you would break down the polyol, which point it will likely flat out ignite, and burn with a very thick, toxic smoke. People used to actually think polyurethane foam was non-flammable. It's highly flammable. It just has a high ignition temperature. In houses, you are now required to cover it with some form of fire barrier or otherwise meet E-84 criteria through additives, etc.
We don't worry too much about this for wood pieces, because the only time they are exposed to this level of heat is when something is already on fire :)
Also keep in mind that things that are called polyurethanes may or may not actually be polyurethanes.
There is the "colloquial" name that you often find for a finish in marketing literature, and then the actual chemistrsy.
A good example is water-based lacquers, which are usually just acrylic resins.
Most polyurethanes are actually polyurethanes of some sort. Everything else is often a wacky mix.
Urushi is the name of the Japanese tree, Toxicodendron verniciflua (the genus formerly was named Rhus), and of the lacquer of which its sap is the main constituent.
The lacquer is also called urushiol (note, not urushoil), which is also the resinous substance found in other members of the Toxicodendron genus: T. radicans and T. rydbergii, or poison ivy; T. diversilobum and T. pubescens, poison oak; and T. vernix, poison sumac. The resinous oil is what causes allergic reactions.
Which finally gets to my point: What are the allergic affects of the tree, its raw sap, the liquid lacquer, and maybe for hypersenstive/reactive urushiol allergies, the finished lacquer?
I don't meant to be alarmist - people have been eating off urushi lacquer for centuries. I'm thinking more about working with it.
EDIT: For those interested in the scientific aspects of the resin, plants, and allergic reaction:
Aaron C. Gladman MD. Toxicodendron Dermatitis: Poison Ivy, Oak, and Sumac. Wilderness & Environmental Medicine vol 17 #2 (June 2006)
The Wood Database can be a useful practical site for this sort of thing. I found [0], a page for a different wood which is said to contain the same allergen:
> The sap contains urushiol (the same allergen found in Poison Ivy), and can still be irritating to some sensitized individuals even after the wood has been dried, and sap can also seep through some wood finishes to the surface of the wood.
Same as poison ivy? Count me out if true: I react badly.
I lament our detour onto the Commercial Highway.
Essentially the same as for any other urushiol.
I'm highly sensitive and had to ask my partner not to get into kintsugi with the traditional lacquers because even the tiniest spot of urushiol and I will be considering a trip to the burn unit.
I've gotten a very mild reaction from ~century old lacquerware but I wouldn't expect that to be common, once it's fully cured. And just because it's mild doesn't mean it's any less itchy, trust me.
Answering my own question, based on reading my own source more carefully (Gladman 2006 p.122):
The Japanese urushi tree, T. verniciflua, is among "plants containing uroshiol cross-reacting chemicals", which are described as follows (note that genus Toxicodendron is in family Anacardiaceae):
"Similar compounds found in other members of the Anacardiaceae family, as well as in several non-Anacardiaceae plants, can lead to cross-reactions and to an identical clinical picture (Table 2). However, dermatitis induced by these cross-reactors is rare compared with the frequency of dermatitis from Toxicodendron species. The allergens in the non-Toxicodendron plants listed in Table 2 are generally noncatechol phenols and resorcinols, and not the highly allergenic catechols in poison ivy, oak, and sumac. The hypothesis that early skin exposure to catechols may allow cross-reaction to other Anacardiaceae, whereas early oral exposure to phenols and resorcinols may induce tolerance, has been expressed."
Regarding the chemical composition, urushiol (in poison ivy/oak/sumac): "is a mixture of 3-n-pentadecylcatechols, which contain a catechol ring moiety substituted with different aliphatic side chains at position 3 or 4."
Nothing wrong with that though, I like reading and watching people do the process and seeing them enjoy the calmness in doing dozens of layers over multiple days. Some end up with very beautiful shimmery brown wooden pieces [0] and I would love to own some of them. It's just not my style.
"Essentially a concentrated form of poison ivy, uncured lacquer causes blistering rashes which cause its sufferer almost unbearable itch and many sleepless nights. Building tolerance typically takes up to two years and has students living in constant fear of the very material they eventually hope to use on a daily basis."
"Lasting natural hyposensitization has been reported, however, among Japanese woodworkers who use lacquer derived from Toxicodendron verniciflua, the Japanese lacquer tree. In a 1991 survey, 81% of craftsmen developed dermatitis from the lacquer but 83% of these reactions resolved with continued exposure."
Granted, consuming it is the worst-case scenario, but exposure to those oils can be life threatening.
https://www.wsj.com/style/eat-poison-ivy-oak-immunity-3207ec...
I find it bizarre that these finishes market the HDI component as an “accelerator”. It seems quite clearly to be a crosslinking agent — it’s a longish molecule with a rather reactive isocyanate group at either end. If you mix it with things it can react with, which likely includes both some waxes (those with hydroxyl groups) and some of the modified oils in “hardwax” oil, it will turn them into something akin to polyurethane.
Rubio Monocoat will cure into a different substance with the “accelerator” added than without it. In either case, it cures quite slowly and IMO has a nasty, penetrating chemical smell for weeks. I like how it looks, but the finish is not as stain resistant as many other options are, with or without the HDI.
P.S. the SDSes and some common sense suggest that this stuff is actually HDI oligomers, not plain HDI. The oligomers are rather less nasty.
P.P.S. Isocyanates are, AIUI, not persistently nasty, as they are too reactive. They react with water to form amines, and unreacted isocyanates will react with the amines to form polyurea, which is reasonably inert.
P.P.P.S. The “molecular bonding” stuff that Rubio talks about seems to be nonsense. The part A + part B mix will cure into a fairly hard and tough plasticky substance even if it’s a millimeter or two thick. Don’t do that — it’s not so easy to get the resulting mess off of whatever surface it cured on!
It's still a combination of polymerizing oils, hard waxes and resin, it's just different plants (linseed instead of tung, pine resin instead of damar etc.) Again, no solvents, people say it smells good.
I still have way too much tung oil, wax and resin around because I could only buy high quantities, so I guess I'll keep using my own finish for a long while. But I'd love to hear from others how the Furniture Butter fares for wooden spoons and cups.
I throw it in a bag and vacuum seal the spoon (with tung oil) for a day or two, then remove, wipe, and let cure for a month.
The resulting finish is largely dishwasher safe for a year or so before I have to reapply. Without the vacuum sealing stage, it doesn’t last as long.
Even for hobby work it’s not hard to get reasonable VOC protective gear or establish a fume extraction hood out of some cardboard and a cheap box fan next to a window in the shop space.
However, as they mention, they do this work from home, and they don't really have a good setup for VOC protection. From the article:
> In the winter months I carve indoors and have to finish the pieces indoors as well, and the horrible solvent smell fills my house for a whole day.
A jury-rigged fume hood will work if you're doing one item at a time, but it doesn't work if you're doing work in batches.
(I get the impression that the best next step for the author, would be to consider building themselves a humidity-controlled drying shed, which would live at least a few feet from their building's air envelope. Doesn't need to be anything fancy; build an ordinary shed, and then get the small-space HVAC equipment from e.g. a marijuana grow-tent supplier.)