Food safe finishes

[Doug Ketellapper]

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.

[David Wilson]

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.

[Cecil Arnold]

I really like Mike Mahoney's Walnut oil/wax finish. If you haven't tried it you should take a look.

[Steve Schoene]

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.

[Jim Becker]

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...)

[Doug Ketellapper]

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!

[Dan Larson]

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

[Kent Cori]

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.

[Jim Becker]

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.

[Steve Schoene]

Here is a link to Federal Regulation 21 section 175.300.

http://a257.g.akamaitech.net/7/257/2422/14mar20010800/edocket.access.gpo.gov/cfr_2003/aprqtr/pdf/21cfr175.300.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

[Howard Acheson]

>> 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.

[Steve Schoene]

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.

[Dan Larson]

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:p
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:p
Confused? :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:p
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:p
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

[Steve Schoene]

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.

[Doug Ketellapper]

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.

[Dan Larson]

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.
Absolutely yes, I agree with you on this point Steve. That is why I felt like I owed you guys a better explaination of my first post.

Dan

[Dan Larson]

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?
Doug, you've zeroed in on an important, and controversal aspect of toxicological profiling-- acute (short term) versus chronic (long term) exposure. Typically toxicological evaluations are acute studies with very high exposures. We then try to extrapolate the risk of chronic exposure at a more realistic dose level based on the findings from the acute studies. Often this approach is valid, yet sometimes it's not. As scientists we defintely prefer to do more chronic studies, but there is a practical limit to how much time we can take to do these things. In the case of high value chemicals, like pharmaceuticals, we can afford to study them very, very extensively before putting them out on the market. In the case of bulk chemicals, this is not always true.

To broadly generalize, yes the effects of exposure to heavy metals tend to be cumulative. Our nation had to deal with this one once we figured out that our daily, yet relatively small exposure to lead from the gasoline that we were burning was slowly poisoning us.

[Steve Schoene]

We are not sure of a great many things. We are absolutely sure of a great many risks that we choose to accept on a daily basis. Taking a shower is one such risk.

Can anyone cite even one documented example of illness caused by (non-lead) metallic driers in clear finishes? (Industrial exposure is another matter entirely, with a potential for more concentrated exposure, and exposure in forms that are more risky such as fumes that may be breathed. And clearly, dumping cobalt into the enviroment should be avoided.) The absence of consumer injury suggests that the magnitude of risk is dramatically less than many of the risks we take daily. Personally, I don't believe the risk being avoided is sufficient to be worth giving up the benefits of BLO for popping grain, for Rockhard varnish on table tops, or for oil based stains and fillers. It seems very alarmist to be warning people away from drier risks while not warning them from getting in the car to do something "frivolous" like seeing a movie, or eating dinner out--activities almost certain to have greater risk of injury than from ingesting crosslinked metal driers from clear finishes.

T&T finishes for example, while liked by some knowledgable people, are also causes for anquish for others who report failure to cure for weeks. That's a risk I don't want to take. I love shellac, but a great many argue for more durable finishes. Mineral oil does just about nothing except giving a bit of color.

[Jim Becker]

T&T finishes for example, while liked by some knowledgable people, are also causes for anquish for others who report failure to cure for weeks.

I have only heard this (and experienced this) relative to the Varnish Oil...the other two formulas (oil and oil/beeswax) have never failed to cure for me. I'd never buy or use the Varnish Oil formula again! (Fortunately, it was the smallest container)

[Steve Schoene]

Thanks Jim for clarifying that about the T&T finishes. I had avoided the whole brand since I had not focused on the varnish oil as the only problem item.

[Jim Becker]

Steve, I especially like the oil/beeswax version for decorative objects. Both it and the oil-only version are VERY thick in the can due to the polymerization process used to avoid the driers and I usually warm them to about 135 degrees in a water bath. (I've done the same with regular BLO, but usually don't in that case for expediency) I get a really silky finish with the stuff...wonderful to the touch.

Acutally, I'll be honest...Dr. SWMBO's cherry desk is finished in the T&T oil/wax formula and has stood the test of nearly 7 years of, umm...abuse. It's been waxed two or three times in that time period, the last time being in late 1999 after we moved to this property. Looks great!

[Tom Spallone]

So, I could use water based poly on my projects and be able to sell them commercially with no repercussion from the FDA?

[Tom Spallone]

So, I could use water based poly on my projects and be able to sell them commercially with no repercussion from the FDA?

[Steve Schoene]

Thats what I believe. There should be a mention on the MSDS if there were an issue.

[nic obie]

Another option is to use nothing at all on your cutting boards. Unless they are just for decoration the finish only gets in the way of the woods natural tendencies to kill harmful bacteria.

The boards will pick up enough oils from the food sliced soon enough anyway. ;)