How to Apply a Food Safe Waterproof Finish to Wood

Ensuring that any woodenware that comes in contact with food is properly sealed with a food safe finish is crucial for health and safety. Whether you are a hobbyist woodworker crafting cutting boards and bowls or a professional producing wooden spoons and salad forks, using the right waterproofing product will protect both your creations and the people using them.

Why Use a Food Safe Finish?

Unfinished, untreated wood is very porous and can easily soak up bacteria, moisture, stains, and odors when used with food. A proper food safe finish creates a protective barrier between the wood grain and the food, preventing contamination.

According to the FDA, any finish, oil, wax, or sealer is considered food safe once fully cured. However, many woodworkers prefer to use food safe finishes made from natural ingredients to limit chemical exposure.

Types of Food Safe Finishes

There are several categories of food safe wood finishes, each with their own characteristics:

• Oils - Penetrating oils like mineral oil, coconut oil, and walnut oil soak into the wood grain to condition and protect it.
• Waxes - Beeswax and carnauba wax create a thin protective coating that repels moisture.
• Shellac - A natural resin secreted from the lac bug that forms a safe, protective film finish.
• Resins - Synthetic film finishes like epoxy and polyurethane provide a plastic-like coating.

Benefits of Using Food Safe Finishes

• Prevent bacteria from growing in knife and utensil handles
• Stop moisture from warping and cracking cutting boards
• Limit food odors from soaking into wood grain
• Allow safe use of handcrafted wood items
• Create a washable, hygienic surface

Choosing a Finish for Your Project

With many options for food safe wood finishes, consider the wood type, intended use, and desired protection when selecting the ideal finish.

Wood Characteristics

The hardness, grain pattern, and porosity of the wood impact finish absorption. Denser woods like maple require less conditioning compared to more porous woods like oak.

Project Use

How the finished piece will be used is key. Items with direct food contact like cutting boards need an oil or wax that can be safely reapplied. Resins work for projects like spoons or salad bowls not constantly washed.

Level of Protection

Will the item be subject to frequent moisture and require waterproofing? Does it need to withstand heat? Consider environment and wear when choosing a finish.

Finish Recommendations by Project

• Oils like mineral oil for safe conditioning and reapplication
• Beeswax adds light water resistance
• Not ideal for thick resin finishes

• Walnut oil, a drying oil, leaves a safe conditioning layer
• Shellac provides a natural film finish and moisture resistance
• Polyurethane if items won't have direct food contact

• Mineral oil for conditioning without changing wood color
• Beeswax and carnauba wax for protection from water
• Pure tung oil penetrates deeply to waterproof

Preparing and Applying Finish

Proper preparation and application technique ensure the finish penetrates deeply into the wood grain to create a durable, evenly coated surface.

Sanding and Conditioning

Sand all wood surfaces incrementally up to 220 or 320 grit for a smooth finish. Higher grits ensure proper adhesion. Remove any dust with a clean, dry cloth. For highly porous woods, apply a layer of mineral oil to condition and let soak in for a few hours before wiping away any excess.

First Coat

Use a clean cloth or high-quality foam brush to apply a thin, even coat. Allow 10-15 minutes for penetration before wiping away any excess. Let dry for a minimum of 24 hours to allow the finish to cure.

Additional Coats

Apply 2-3 additional thin layers, lightly sanding with 320 or 400 grit sandpaper between each to create a smooth surface profile. Wipe away any dust and degrease for proper adhesion. More coats are recommended for softwoods while fewer may be needed for extremely dense hardwoods.

Curing

Allow the final coat to fully cure, meaning the finish is dry to the touch and no longer smells like wet oil. Different products have varied cure times, ranging from several days for oils to several weeks for surface finishes like polyurethane.

Maintenance

While a food safe finish seals and protects the wood, regular maintenance helps ensure longevity.

Cleaning

Use mild soap and warm water to clean woodware, towels dry immediately to prevent warping. Avoid harsh detergents or abrasive scrubbers that can degrade the finish over time.

Reapplication

Reapply a fresh layer of oil or wax once or twice per year for items like cutting boards, salad bowls, and utensils that see heavy use. This maintains protection. Allow to fully cure between reapplications.

Touch-ups

Inspect for any nicks, cracks, or worn areas that expose bare wood. Spot treat these by lightly sanding only where needed and applying more finish. This prevents damage from moisture.

Avoiding Soap Build-up

For items cleaned frequently with soap and water, use a dilute vinegar solution to remove any alkaline film build-up which can degrade the wood over time.

Proper Drying and Storage

Always hand dry woodware immediately after washing. Allowing it to air dry can lead to warping. Store in a cool, dry place away from direct sunlight.

Types of Food Safe Wood Finishes

There are a wide variety of both natural and synthetic options for food safe wood finishes. Consider the characteristics of each when selecting the right one for your project.

Oils

• Petroleum-based, penetrates deeply into wood pores
• Leaves no odor or taste
• Minimal water resistance, must reapply frequently

• Pressed from walnut nuts, conditions wood naturally
• Low odor, light amber tint
• Drying oil, higher water resistance than mineral oil

• Pressed from tung tree nuts, thick and durable
• Deep penetration, ideal for waterproofing
• Long cure time, can take weeks to harden fully

Waxes

• Secreted from honeycombs, natural water repellant
• Smooth protective coating builds up with layers
• Buffs easily to a nice sheen

• Derived from palm leaves, extremely hard wax
• Excellent moisture barrier, heat resistant
• Labor intensive to apply and buff out

Resins

• Secreted from lac beetles, ages well over time
• Transparent, enhances natural wood grain
• Prone to water spotting, best for low-moisture items

• Plastic-like synthetic resin, high durability
• Excellent moisture resistance
• Can crack or chip if item is washed frequently

FAQs

How do I get a smooth finish?

Use higher grit sandpaper (220+), apply thin coats, and lightly sand between layers. Refrain from overbrushing as this can create bubbles.

What are food safe epoxies?

FDA-approved epoxy resins made without BPA or volatile solvents are considered food safe once fully cured. Popular choices are bartop or tabletop epoxy resins.

Can I use polyurethane over oil?

For items wanting conditioning oil plus a protective topcoat, apply oil first then top with polyurethane once cured. Degrease between layers for adhesion.

Applying a food safe finish to wood projects allows for both beauty and practical utility. With this comprehensive guide covering preparation, application, maintenance, and the myriad finish options, you can achieve stunning results on your handcrafted woodenware.

Tailor your approach to the needs of the project, characteristics of the wood, and desired protection. Anticipate wear and environment for long-lasting creations. With the right food safe waterproofing, your boards, bowls, spoons, and more will remain beautiful and functional works of art for years to come.