DEAR TIM: It's time again to clean and seal our wood deck. I have watched a number of TV shows that advocate the use of pressure washers and a mixture of chlorine bleach and water. I am afraid that a pressure washer will harm my wood deck, but the TV shows made it seem so simple and easy to use. What is a good way to safely clean a wood deck? What is the best sealer to use once I have finished? Jackie F., Versailles, KY

DEAR JACKIE: Many of those TV shows bring a smile to my face. They often create a fantasy land where household projects go smoothly, the workers rarely sweat, and there are never any problems. My twenty plus years of experience in the field tell me that the exact opposite is true of most home improvement projects. Cleaning wood decks is no different. If you want excellent results you have to do some work, but it is not that hard.

Using a pressure washer to clean a wood deck is a huge mistake in my opinion. High pressure streams of water easily erode the soft light colored spring wood that is found in between the darker bands of summer wood on each piece of lumber. I have actually cut my hand on pressure cleaned deck handrails. So much soft wood was eroded by a pressure washer that sharp slivers of summer grain wood were left behind. The surface of the handrail resembled an upside down multiple blade razor.

To make matters worse, many of the pressure washed decks I have examined were cleaned by professional deck cleaning companies. If you have no experience working with a pressure washer, the last place to start is a wood deck.

If you want to make an even bigger mistake, then use chlorine bleach to clean your deck! In my opinion, it is the absolute worst ingredient to apply to a wood deck. Chlorine bleach, better identified on deck cleaning product labels as sodium hypochlorite, removes the natural color from your wood, it destroys the lignin or glue that holds together the wood deck fibers, is toxic to surrounding vegetation, and is corrosive to all metal fasteners and components that hold your deck together.

A far better wood deck cleaner is oxygen bleach. This powdered product when mixed with water releases non-toxic oxygen ions that kill mildew and algae. In addition, the foaming oxygen bleach loosens grey weathered wood fibers and dirt from the deck surface. In the process, it does not remove natural wood color, nor does it hurt nails and joist hangers. Possibly one of oxygen bleach's best attributes is that it will not harm plants, vegetation or you.

I have found that .
the best way to clean a wood deck is to mix the powdered oxygen bleach with warm water. Once the powder is dissolved, you liberally apply the solution to the wood surface. It immediately foams up as the oxygen ions attack the mildew, algae and dirt. I prefer to let the solution sit for 10 or 15 minutes. Using a scrub brush on a pole or a large push broom to gently scrub the surface to lift wood fibers and dirt. To complete the cleaning process you simply use a regular garden hose to rinse away all traces of dirt and grime.

Over the past few years popular consumer magazines have revealed that many deck sealers perform poorly. Most, if not all of the ones tested, contain animal fat, vegetable, linseed, and other natural oils that are food for mildew and algae. It is no wonder decks turn black and green after the water soluble mildewcides contained in these products are washed away by repeated rainfall. If you want lasting results from a deck sealer, you should apply one that contains synthetic resins.