How to Preserve Unfinished Cedar Wood

Preserve cedar wood with a UV-blocking water-repellent sealant.

Cedar is an excellent hard wood with fragrant oils that not only smell wonderful but also deter insect pests and fungi and enable the wood to resist rot. It dehydrates evenly and holds its shape. All of these features---along with its beautiful grain and texture---make cedar wood a popular choice for exterior applications such as fencing, decks, patio furniture and house siding. Preserve the beauty of natural cedar and protect it from sun damage by treating it with a water-repellent sealant. This will seal in the natural chemical preservatives of the wood, which otherwise leach out during rainfall.

Things You'll Need

• Household bleach
• Dish-washing detergent
• Rags
• Water-repellent sealant
• Paint brush, roller or painting pad
• Hose and water supply
• Scrub brush
• Rubber gloves
• Sander and sanding paper

Instructions

1. Wash new unfinished cedar and let it dry completely. If the unfinished wood is already weathered and gray you will need to power-wash it and remove mildew and algae.

2. Mix 1 qt. household bleach to 3 qts. water and add 1/4 cup of liquid detergent. Wear rubber gloves when you apply this mixture to the cedar with a rag. Let it soak into the wood for at least five minutes to kill the mildew. Use the bleach solution with a hard bristled brush to scrub off any remaining mildew and algal growth. Rinse the cedar with water and let it dry completely.

3. Use a medium grit sandpaper to sand the wood down past all surface damage. Brush the wood clean.

4. Apply an even, fairly thin coat of sealant to all sides of wood with a brush, roller or paint pad, avoiding drips and runs.

5. Allow the wood to completely dry--at least 48 hours--and apply a second coat.

Tips & Warnings

• Read the labels of possible sealants. Choose a transparent water-repellent sealant with UV blockers and fungicide.

• Some sealants need to be stirred or mixed prior to use.

• Cedar will always eventually turn gray from weatherization and sun damage. To prolong the natural look of your cedar, be sure to apply your UV blocker annually. Apply sealant during warm weather for best results.

• Do not paint or seal wet wood. The sealant will fail.

References

• InspectAPedia: Buildings and Envirnomental Inspection, Testing, Diagnosis, Repair
• USDA-NRCS: Plant Guide, Western Red Cedar