Q & A: Is Polyurethane Food-Safe?
Is Polyurethane Food-Safe?
I’m planning on finishing a set of wooden plates with polyurethane. Is this finish safe for food?
According to finishing expert Bob Flexner, all finishes are food-safe once they have cured. Polyurethane varnish does not present any known hazard.However, no finish is food safe until it has fully cured.The rule of thumb for full curing is 30 days at room temperature (65- to 75- degrees F).
The question of food safety in finishes revolves around the metallic driers added to oils and varnishes to speed the curing process. Lead was used as a drier many years ago,but now lead is banned.
There is no evidence that today’s driers are unsafe.No case of poisoning from finishes containing these driers has ever been reported. The Food and Drug Administration approves the use of these driers in coatings, and no warnings are required on cans or Material Data Safety Sheets.
Several oil and varnish products are marketed as “food or salad-bowl safe.”This implies that other finishes may not be safe, but that’s simply not true. Some of these specially labeled products have no driers added to them (and they take quite a long time to dry!), but the rest actually contain the same kinds of driers as other oils and varnishes.
This story originally appeared in American Woodworker June 2002, issue #94.