Despite what you've read elsewhere, almost every wood finish should be
considered food-safe.

By Bob Flexner

It's a shame, but many woodworkers worry about which finish to use on
objects that will come into contact with food or children's mouths. The
reason for the worry is that woodworkers have been conditioned by several
decades of articles in woodworking magazines to believe that ordinary
finishes like boiled linseed oil, alkyd varnish and polyurethane varnish may
leach poisonous ingredients like metallic driers. And other finishes, like
lacquer, catalyzed (two-part) finishes, shellac and water-based finishes,
may leach poisonous solvent. 

The idea that some finishes are harmful is reinforced by a few manufacturers
who label their finishes food- or salad-bowl safe, which implies that other
finishes are not. 

A Non-Issue
The shame for woodworkers is that a lot of energy is spent on the issue of
food safeness when none is warranted. Food safeness is a non-issue because
there's no evidence of any problem. So far as we know, all finishes are safe
to eat off of, and safe for children to chew on, once the finish has fully
cured (the rule of thumb being 30 days). 

Think About It
. Have you ever heard or read of anyone, child or adult, being poisoned from
contact with a cured, non-pigmented finish? 

. Is it likely that any finish could be sold in paint stores or home centers
without a warning if the finish were known to be dangerous for food or mouth
contact? (Paint store clerks are rarely even aware that there might be an

. If there were any evidence that common wood finishes were unsafe for food
or mouth contact, why is no mention made on the MSDS (material safety data
sheets)? All unsafe uses of products are required by law to be listed on
these forms, along with information about treatments for resulting health

. Finally, does it make any sense that commonly available oils and varnishes
that contain driers and solvents could be a health risk while the so-called
"food safe" oils and varnishes, which contain the same driers and solvents,
aren't a problem? (These finishes wouldn't cure without the driers and would
be too thick without the solvents.) 

I want to make clear that I'm not saying that all finishes are food safe --
we can't be absolutely sure about the safety of any curing finish. I'm
saying that there is no evidence of any common wood finish being unsafe for
food or mouth contact once it has fully cured, so a distinction between
food-safe and non-food-safe is speculative. 

For those who would then reply, "Well, there's no point in taking a chance,"
I would say that we take chances everyday with almost everything we come in
contact with. To rule out certain finishes when there's no evidence of a
problem is unreasonable and arbitrary. 

A lot of the discussion about food safeness centers on what the Food and
Drug Administration (FDA) allows. The FDA doesn't approve products, it
regulates them. And it has published a set of regulations for establishing
the food safeness of finishes. These regulations are contained in the Code
of Federal Regulations, Title 21, Part 175, which you can find at larger
public and university libraries. 

There are two conditions for meeting FDA regulations. 

. First, the finish must be made from among the raw materials listed on nine
double-columned pages (additional ingredients can be added by a petition
method). This list includes every oil, resin, drier and additive commonly
used in wood finishes (polyurethane is covered in Part 177). It does not
include lead or mercury. Because lead is no longer used in common wood
finishes, and mercury never was, it can be assumed that all common wood
finishes use only FDA-approved ingredients. 

. Second, the finish must be formulated in such a way that it does not leach
more than a specified amount of extractive when subjected to a variety of
specified tests. The point of these tests is to show the finish cures
properly. It's important to note that these tests must be done on every
batch of finish to establish that no foreign substance has gotten into the
finish (for example, from the finish having been made in a dirty vat), and
that these tests are expensive. 

No manufacturer providing finishes to the woodworking community puts their
finishes through these tests. Thus, no manufacturer can legitimately claim
they meet FDA regulations. 

On the other hand, there's no evidence of problems, so manufacturers feel
pretty safe in claiming food safeness anyway.

"Food safeness is a non-issue because there's no evidence of any problem. So
far as we know, all finishes are safe to eat off of, and safe for children
to chew on, once the finish has fully cured."

The Issue of Metallic Driers
Metallic driers are added to oil and varnish finishes to speed curing.
Without driers, these finishes take many days or weeks to cure. 

Lead driers were once commonly used in oil and varnish finishes, but in the
1970s it was learned that lead is highly toxic, especially to children. The
problem was associated with the relatively large amount of lead contained in
pigment and not with the tiny amount contained in clear finishes.
Nevertheless, to be safe, lead was removed from all commonly available
paints and finishes, including oils and varnishes. (Lead is still used in
some specialty art and marine finishes, and labels are required to disclose
its inclusion.) 

Other metallic driers, including salts of cobalt, manganese, zirconium and
zinc, continue to be used in all varnishes and curing-oil finishes except
raw linseed oil and pure tung oil. Without these driers, these finishes cure
extremely slowly. 

There is no indication that these driers cause health problems. A very small
amount is used, and it is well encased in the cured finish film so that if
any is ingested, it passes through the body without causing harm. 

Other Finishes
All other common wood finishes also are safe for food and child contact. In
fact, commercially made wooden bowls, baby beds and children's toys are
usually coated with one of these finishes. 

The solvents, which cause some people to worry, evaporate out completely
enough so they aren't a problem. And catalysts, which can be toxic in their
liquid state, become so fully reacted with the finish that there is no
evidence of a problem. 

The issue of food safeness in finishes is a classic case of the concept
"validation by repetition." Consistent, long-term repetition in woodworking
magazines of a food-safeness issue, despite the complete lack of supporting
evidence, has led to a widely held belief in the woodworking community that
food safeness is an issue. 

It shouldn't be. No other segment of society treats it as such. A more
reasonable approach is as follows. 

You can't be absolutely sure about the food safeness of any finish you put
on wood. There could even be problems with mineral oil and walnut oil that
we just don't know of yet. There could also be problems with raw linseed
oil, pure tung oil, wax, shellac and salad bowl finish, because we don't
know where these substances have been or what they might have come in
contact with. None has met the regulations laid out by the FDA. 

But, based on FDA regulations, the way finishes are made, the complete lack
of any evidence to the contrary, and the countless other untested objects
food and children come in contact with, there's no reasonable argument for
avoiding the use of any finish. PW 


Bob Flexner is a contributing editor to Popular Woodworking and the author
of the book, "Understanding Wood Finishes," (Rodale Press) which is a
must-read book for any woodworker who wants to understand finishing. Bob's
column appears in every issue of Popular Woodworking.


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