Cleaning a wood deck is essential for maintaining its appearance and longevity. The process not only aims to remove dirt, grime, and mildew but also prepares the surface for staining or sealing. The choice of chemicals is crucial to ensure a thorough clean without damaging the wood. Here’s an overview of the cleaning process, suitable chemicals, and their commercial versions, including considerations for using oxalic acid and sodium hypochlorite (SH).

Step 1: Preparation

• Remove Furniture and Debris: Clear the deck of furniture and other items. Sweep off loose debris and dirt.

Step 2: Choosing the Right Chemicals

• For General Cleaning and Brightening: Oxalic acid is excellent for restoring the wood’s natural color and removing stains without harming the wood’s integrity. It’s particularly effective against rust stains and for brightening the deck.
• For Mildew and Algae: Sodium percarbonate (oxygen bleach) is safer for the wood and the environment compared to chlorine bleach (sodium hypochlorite). It effectively cleans mildew and algae without the risk of discoloring the wood.
• For Deep Cleaning Before Staining: A deck cleaner that contains a blend of surfactants and sodium percarbonate can prepare the wood for staining by removing old finishes and opening up the wood’s pores.

Commercial Products

• Oxalic Acid-Based Cleaners: Products like Savogran Wood Bleach contain oxalic acid and are designed to brighten wood and remove stains.
• Sodium Percarbonate-Based Cleaners: DEFY Wood Cleaner is a popular choice that uses oxygen bleach for a safe and effective clean.
• Multi-Purpose Deck Cleaners: Olympic Deck Cleaner and Simple Green Deck and Fence Cleaner are formulated to clean and prepare decks for staining without damaging the wood.

Step 3: Application

• Dilute According to Instructions: For chemical cleaners, follow the manufacturer’s dilution instructions carefully.
• Apply Evenly: Use a garden sprayer, roller, or brush to apply the cleaner evenly across the wood. Avoid pooling to ensure an even clean.
• Let Sit and Scrub: Allow the cleaner to sit for the time recommended by the manufacturer, then scrub the surface with a stiff brush to loosen dirt and grime.

Step 4: Rinsing

• Use a Garden Hose or Pressure Washer: Rinse the deck thoroughly with water. If using a pressure washer, keep it on a low setting to avoid damaging the wood.

Chemical Considerations

• Oxalic Acid: Ideal for brightening and removing specific stains but may not be sufficient for killing mold and mildew. Always neutralize the acid after use by rinsing the deck thoroughly.
• Sodium Hypochlorite (SH): Effective against mold and mildew but can damage the wood and discolor it if not used carefully. It’s generally not recommended for wood decks due to its harshness.
• Sodium Percarbonate: Offers a good balance of efficacy and safety for both cleaning and preparing the wood for staining.

Conclusion

The goal of cleaning a wood deck varies, but the overarching aim is to achieve a cleaner, brighter surface without causing damage. Choosing the right chemical depends on the specific needs of the deck—whether it’s general cleaning, stain removal, or preparation for staining. Oxalic acid and sodium percarbonate-based cleaners are generally safer and more effective choices for wood decks, providing a thorough clean while preserving the wood’s natural beauty and integrity. Always follow the product instructions and perform a small patch test before cleaning the entire deck to ensure the selected cleaner is appropriate for your wood type.