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Ask the Staff


Question:

Hello,

I am making wooden spoons and salad bowls commercially. Which surface finish should I use? I very much like the quality of General Finishes and Graham paint products that I have bought from Highland Woodworking. The web sites of the manufacturers show the safety documentation of their products in the packaging, including the solvent. I would like a similar certificate of safety for the finished dry wooden product. How could I obtain such a certificate?

Respectfully,
Aleks Bakman
Denver, Colorado


Answer:

Aleks,

Unfortunately, companies do not "certify" their finish products from a food safety standpoint. Some companies promote their finishes by offering a government statute from the FDA that relates to resinous coatings coming into contact with food surfaces. Read about it here, and see one of the products that meets the government criteria here.

Here are some more general thoughts on finishes that we share with our customers looking for "safe" finishes:

All the toxic lead-based dryers used in the past are gone from the paints and finishes woodworkers use for interior wood projects (and from exterior finishes as well, though some marine coatings for boat bottoms could contain high levels of metals or other "toxins" designed to inhibit organisms from growing.)

Once the solvent that carries the "solids" part of the finish has evaporated and the finish is fully cured (no more finish smell when you take a whiff with your nose next to the finish), the coating is safe to come into contact with food or the mouth.

The solvents in a finish, in its uncured liquid state, are a different issue. Some of the products labeled as a "Salad Bowl" finish have poisonous solvents (paint thinner) in them. But once the thinner evaporates, the coating you are left with is often cured tung oil/alkyd resins (varnish). While varnish is not intended to be eaten, if you should ingest some bits from chopping food on your counter top with the cured finish, you may eat small amounts of the inert material. Consider it unappetizing, but not inedible from a food safety-standpoint.

Shellac is often used for children's toys and furniture. A discharge from the lac bug (in Asia) is what shellac solids consist of, thus it is very natural. Of course, denatured alcohol is the solvent for shellac, which if you drink it, will harm or kill you. But the solvent evaporates and what is left is the shellac. Shellac is used widely in the food and pharmaceutical industries to coat food and pills. You could use 200 proof grain alcohol from the liquor store to mix up pure shellac flakes. It would melt the flakes and serve as a carrier so you can apply the finish. Grain alcohol is not poisonous like denatured "wood" alcohol, and so some people may experience less sensitivity to being exposed to grain alcohol instead of denatured alcohol.

There are some finishes in the market place that contain no solvents. These may better protect the person actually applying the finish than other finishes because they may not have any solvent fumes, but be wary of any label throwing around the word "natural". The government has no definition of the word that must be strictly adhered to and thus, while non-toxic when dry, most of today's finishes still have solvents that have health issues if you breathe or are exposed too much to the solvent. Women who are pregnant should avoid applying solvent-based finishes. Always read and follow the manufacturer's safety precautions on the product's label.

Some people will use mineral oil on a butcher block counter and wooden utensils. This is a non-curing oil finish. It fills the pores a bit on the wood but doesn't do much in the way of protecting the wood and will evaporate with time, needing to be reapplied. But it is better than applying nothing.

There are some plant/tree curing oils that have no solvents which are heat treated to allow them to dry fully (albeit the process is a bit slow). If you want to consider a walnut oil finish, this one is a great option.

The main reason for applying a finish to a wood project is to mitigate the seasonal movement of moisture in and out of the wood. An adequate finish assists in keeping the joinery work from failing over time by minimizing this wood movement. Of course finishes also offer protection from spills and stains and can give a glossy surface look to the furniture to varying degrees.

You can safely use just about any oil or water-based polyurethane, varnish, lacquer, shellac, or wipe-on finish. Just let the finish dry well before use. A finish that is dry to the touch may not be "completely cured". If you put your nose to a dry finish and cannot smell any solvent, the finish is completely cured. This may take a couple of days (shellac) or up to three weeks (some wipe-on oil/varnishes).

Regards,
Ed Scent
Highland Woodworking

 

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