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Thread: Food safe finishes

  1. #1

    Question Food safe finishes

    I am currently finishing up some end grain cutting boards as gifts. I know there are commercial finishes available such as Behlen Salad Bowl finish, but I've also heard of some homemade finishes involving mineral oil or walnut oil and beeswax mixed. I was just curious as to what others have used and have had success with.

  2. #2
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    I use straight mineral oil on my toaster tonges with good results. Try some on a scrap and let it sit for a couple minutes. Wipe off the excess and let it sit over night. See what you think.
    Those who sense the winds of change should build windmills, not windbreaks.

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  3. #3
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    I really like Mike Mahoney's Walnut oil/wax finish. If you haven't tried it you should take a look.
    Good, Fast, Cheap--Pick two.

  4. #4
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    Any clear finish is going to be food safe. You don't want to build a film, of course, for practical, not safety reasons.

    Mineral oil never cures, I'm not too fond of that, but it is commonly used. Wax can be melted into the mineral oil for a bit of sealing, also commonly used.

    If I am sure I would have plenty of time before giving them (30 days), I would use an oil/varnish mix, such as Watco. You need plenty of time for it to fully cure, both to be certain about the food safety, and more importantly, so there will be no lingering odor of the finish.

  5. #5
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    To expand upone Steve's first sentence...all finishes sold today are "food safe" (which is an arbitrary thing) once fully cured. The last two words are important.

    Personally, I do use mineral oil on such things. Yes, it doesn't cure, but it's easily and cheaply renewable as the piece gets used and washed. (which shouldn't be with soap...ahem...)
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
    I work in a food related industry, and the FDA is quite specific as to what is and isn't food safe. I don't understand your arbitrary comment, unless you mean you can do whatever you want at home. I personally don't want to use finishes that contain any metal driers like Watco Danish oil does. Mike Mahoney's oil finish is something I've heard of some time ago, thanks for reminding me of it Cecil!

  7. #7
    Quote Originally Posted by Doug Ketellapper
    I personally don't want to use finishes that contain any metal driers like Watco Danish oil does.
    I second that motion. My background is in medicinal chemisty & toxicology. I prefer to avoid finishes that contain metallic driers as much as possible. Definitely wouldn't chop my veggies on a cutting board with this type of finish.

    Check out Tried & True finishes. Quote from their website: http://www.triedandtruewoodfinish.com/standards.htm

    "All Tried & True Wood Finishes comply with the inner most circle of product safety established by the FDA: "safe for food contact surfaces" (FDA 21,Sec 175.300)."

    You can buy their products at your local Woodcraft or from Lee Valley.

    Dan

  8. #8
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    I use Walnut oil on most of my cutting boards. You can find it at a well stocked health food store. They sell it as salad dressing so it is obviously food safe. However, there is a remote chance that someone with an alergy to walnuts could react to the oil on the board.

    I've also used mineral oil but don't like it quite as well. However, it is readily available and cheap.
    Kent Cori

    Half a bubble off plumb

  9. #9
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    While I am certainly a fan of T&T because I like it as a finish, the "food safe" thing has been argued about over and over by folks for years and I've never seen anything posted that indicates the FDA as specific regulations relative to finishes. If there are, please post them or a link to them. That said, you should always use what you are most comfortable with for wooden objects that will be used with food. For me, that is mineral oil. I have not tried walnut oil as Kent mentions, but do know that many folks are happy with it, too.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  10. #10
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    Here is a link to Federal Regulation 21 section 175.300.

    http://a257.g.akamaitech.net/7/257/2...cfr175.300.pdf

    It is about 17 pages of smallish print, and was written by lawyers. Most of those pages are devoted to listing acceptable ingredients.

    It is true that the T&T finishes fall within the rule. What T&T don't tell you is that apparently all the other clear wood finishes do too. Manufacturers seeking to sell to the food industry cite their compliance, manufacturers not marketing specifically to that industry don't. That's why is looks like the FDA is being very restrictive. In fact it is mostly marketing.

    Bob Flexner in his recent revised edition of Understanding Wood Finishing addresses this point specifically. In a sidebar on page 76 titled "The Food Safe Myth" he notes that the list includes all the common driers as safe for food as long as the finish cures. He also notes that the FDA does not "approve" of specific finishes, but only approves of the list of ingredients, and rules for testing that the finish cures properly.

    Among the ingredients listed as permitted in 175.300 b(3)(xxii) are "Driers made by reaction of a metal from paragraph (b)3(xxii)(a) of this section with acid, to form the salt listed in paragraph (b)(3)(xii)(b) of this section:
    (a) Metals:
    Aluminum
    Calcium
    Cerium
    Cobalt
    Iron
    Lithium
    Magnesium
    Manganese
    Zinc
    Zirconium
    (b) Salts:
    Caprate
    Caprylate
    Isodecanoate
    Linoleate
    Naphthenate...."
    [and so on]

    Edited for typos
    Last edited by Steve Schoene; 01-05-2006 at 10:54 AM.

  11. #11
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    >> all finishes sold today are "food safe" (which is an arbitrary thing) once fully cured

    It's a nit but the government uses the words "non toxic", not food safe. All finishes since the mid 1970's have been required to be non-toxic when fully cured. It goes back to the "get the lead out" movement. The toxcisity of finishes does not fall under any of the organizations that deal with food or food contact. As far as I know, and as Steve has said, no food products are specifically rated "food safe".

    The metallic driers are in such small quantities that the government does not consider them to toxic or harmfull.
    Howie.........

  12. #12
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    Actually, the exact wording of the rule is :

    "Resinous and polymeric coatings may be safely used as the food-contact surface of articles intended for use in producing ... food, in accordance with the following prescribed conditions:...."

    emphasis added

    the term non-toxic is not used in this FDA rule. I think it is used in the context of MSDS reporting, and Flexner does tell us that no MSDS for clear finishes warn against any toxic effect relating to food contact.

    The rule does address finishes but not by brand or product, only by ingredients, and by defining limits on how much "stuff" may leach out under conditions of use, along with the methods of doing that testing. I certainly don't under stand the testing proceedure, but I assume that Flexner does, or talks to people that do. His conclusion implies that all finishes that cure would pass these tests.

  13. #13
    OK, I regret even bringing up the Tried & True claim of being “food safe”. Mentioning this has stirred up a can of worms, and that wasn’t my intention. I’m not going to spend the time and energy to trying to evaluate the book by Flexner that was mentioned in another post. I’m also not going to stamp my feet and claim that other information offered in this thread is wrong. Nor am I implying that anyone else has done this either. However, I now realize that I should put my previous comments in a more complete context.

    I make my living inventing new pharmaceuticals. I wouldn’t claim to know everything there is to know about toxicology, but I’ve spent many years of my life studying the effects of chemical compounds on humans. So I think I’m at least qualified to weigh in with an opinion here.

    The issue I was getting at was with evaluating the risks associated with exposure to metallic driers that are often found in oil-based finishes. How much exposure is OK? Is it safe to use such a finish on something like a salad bowl? I would agree that a curing finish will encapsulate the metallic driers to a large extent, but I do think that abrasion of the finish will expose small amounts of the metallic driers over time.
    <O
    Metallic driers are heavy metal salts like cobalt diacetate, cobalt dichloride, manganese dichloride, manganese dioxide, etc. Let’s take a look at cobalt dichloride as an example in order to put things into perspective. Clinical data suggest that a lethal dose of this chemical in an average human might be in the range of 10-20 grams. It would be very unlikely that a person could get a fatal dose of this chemical from the finish on a salad bowl. Other clinical data indicate that “large exposures” to this chemical can depress erythrocyte production, lead to death in children, skin disorders, cause chest pains, nausea & vomiting, nerve deafness, thyroid disorders, and congestive heart failure. How much is a “large exposure”? Probably a lot more than you might get from the salad bowl in question. So this stuff really is safe, isn’t it? Well for example, I don’t see any data about what the effects would be if a child were exposed to small amounts of this compound for a number of years? It would be hard to know for sure without doing the study. Maybe it’s OK, but maybe not.
    <O
    Confused? You should be. Evaluation of toxicological risks is hardly ever a clear-cut thing. Scientists run experiments and then make their best guess based on the results of these experiments. And there’s a practical limit to the number of experiments that can be run. In the end, though, it’s only an educated guess that’s being made.
    <O
    So is it risky to use boiled linseed oil to finish your salad bowl? Probably not. But my feeling is that there is no reason why I should even worry about it when I can use products that don’t have metallic driers-- like mineral oil, walnut oil, or a product like Tried & True instead.
    <O
    Don’t get me wrong— life is full of risks and it’s silly to even try to protect ourselves from every conceivable risk. We all just need to pick the ones that we care about. This one just happens to be a pet peeve of mine. In my case, I gave it some thought, and decided that I’d prefer to use finish products that contain metallic driers only when a reasonable alternative doesn’t exist. You might decide that I’m completely wacko, and disregard everything I’ve just written. No hard feelings intended here. Just thought I’d try to explain myself a little better this time.

    Dan

  14. #14
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    No hard feelings at all, but it doesn't seem like very good general advise for those of us willing to accept reasonable risks in order to use more tractable finishes. I don't know whether the risk is more like crossing the steet or like taking a holiday trip on the interstate highway, but given the pausity of cases actually alleging such injury, it seem likely that the risk is substantially less than those common activities. Given your occupation it is perfectly sensible for you to avoid crossing that particular street.

  15. #15
    Thanks for that reply, Dan. That pretty much sums up how I feel about the topic. One additional question from a toxicological perspective. Aren't exposures to heavy metals somewhat cumulative? As in they tend to stay in the body in places like the liver for long periods of time?

    Steve, I don't see why it's not good advice to avoid risks you are unsure of when there is a perfectly reasonable and easy alternative to what you call more "tractable" finishes in the case of food contact. The other part of the equation is that I am making these cutting boards as gifts, so I'd also rather not make that choice for someone else, and go with the more benign product.

    As a final note, I've decided to go with the Mike Mahoney finishes (thanks again Cecil); his walnut oil, and his walnut oil/wax mixture. I'll report on how they worked out for me.

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