A pressure washer is a machine that compresses air and then mixes it with water supplied from a garden hose. The result is water that comes out of a washing wand under very high pressure from 800 to 3000 psi (pounds per square inch). Air-assisted water emitted from a small port at 3000 psi could easily drive metal particles through a person's hand. Actually, a pressure washer is even more powerful than the air-assisted machines at a you-do-it car wash.

Pressure washers in the 3000-psi range are used commercially for heavy-duty cleaning jobs. For example, painters use heavy-duty pressure washers to remove paint from the exterior of an entire home. For do-it-yourselfers, 1500 psi is usually more than sufficient pressure. Some companies rate pressure washers using two values: the psi rating and the gallons-per-minute flow of water. Others use a value that results from multiplying the psi rating times the gallon-per-minute flow of water. For example: a 3000-psi machine that uses six gallons of water per minute would be referred to by the latter as a machine that generates 18,000 units.

In planning a television segment on pressure washers we decided we wanted to show as many different uses for them as we could. We knew them to be versatile, but never realized until we began filming how much so they were. We cleaned sturdy surfaces and fragile ones as well ö all with the same machine.

Redwood deck cleaning was first on our list. Turning gray wood red impressed everyone including the cameraman and producer. Next, was house cleaning ö ridding exterior walls and eaves of spider webs and insect nests. Windows were next. Cleaning the glass was the obvious objective, but brightening the metal frame was also accomplished. Opening weep holes in the frames was easy to do. And the screens were a breeze. Dirt disappeared instantly. Naturally, the screens had to be removed before they could be properly cleaned.

Next were plastic and metal patio furniture and kids toys, including a tricycle and a race car. All were located under a large patio flown over by a pair of territorial blue jays. Need we say more? A large cypress tree covered with dead leaves and spider webs also needed cleaning. After five minutes of gentle spraying, the shrub was ready for presentation in a regional horticultural event.

After that, we "de-charred" a barbecue grill. No mess, no fuss, no bother. Just spray and shine. Then, we cleaned a few grease-covered hand tools. Moss growing on a concrete statue took a little longer to clean because the statue was made of porous concrete. Cleaning a stain from the driveway also was time consuming, again due to porous concrete. Yet the stains disappeared completely, as did all the dirt and debris in the path of the powerful washing wand.

We cleaned a lot of different things for our TV segment. And if time had permitted, we could have cleaned roof shingles, fence boards and gate hardware, sliding glass door tracks and garden tools. And, rain gutters downspouts and the family car also would have been fair game.

With a pressure washer, it is interesting how easy it is to manage the degree of pressure needed to clean a given surface. Changes in pressure can be controlled by a regulating device on some machines, but the best control is managed by altering the distance between the tip of the washing wand and the surface being cleaned. The less distance from tip to surface, the more cleaning power. Increase the distance for a more gentle cleaning power.

Different types of tips also are available. Some spray in a tight circular pattern and others in a wide fan-like spray. The first are better for hard-to-clean surfaces. The latter are better for more gentle work such as cleaning spider webs, furniture, plants and shrubs.

We did not need to use any cleaning chemicals during our day of filming, yet everything we washed sparkled. Had we actually run into a troublesome spot we could have introduced the appropriate cleaning chemical through a tube provided on the pressure washer. We could have used mild detergent on the car that we washed, an acid (phosphoric or muratic) on the concrete surface that we cleaned, and when we did the deck, we could have introduced a wood bleach such as oxalic acid.