Pressure washing vs. water blasting for cottage cleanup

Having descriptive conventions, like the use of Latin names in science to trump colloquial terms, thus avoiding confusion, is important when speaking of tools and processes. An accurate description lets you refine your selection of the appropriate device and its use. For instance, many households now have a pressure washer, but few realize all that it’s capable of. Based on my years of cleaning wooden components and decks, here are my thoughts on differentiating and mastering the capabilities of this tool.

Pressure washing
A pressure washer comprises a water pump, driven by an electric or gas motor, and a series of hoses, wands, and nozzles to transfer the pressure boosted water. Water spray nozzles come in varying degrees of fan pattern, such that the narrower the fan, the higher the water pressure. There will often be a jet nozzle, which is a straight stream, and thusly the highest-pressure stream your unit will be capable of delivering. This stream is weapon-like, so take caution!

For the purpose of cleaning surfaces, use the broader fan nozzles, as they’re just amplifying the existing line water pressure to the point where the force of the blast is sufficient to dislodge dirt and loose material. Depending on which nozzle you select, and the power of your washer, this will determine how far from the surface you need to hold the wand and nozzle end in order to have an adequately aggressive spray. There isn’t a lot of technique required for washing surfaces, but realize that even a benign water stream can get under surfaces you didn’t intend, and could dislodge loose soffit and fascia components. You should also generally work from the top of your project downward, so that gravity is also helping to remove the grime.

Use pressure washing for cleaning the following at the cottage:

Siding and decking that requires seasonal cleaning

Cleaning the hull and deck of your boat before winter storage

Outdoor plastic and wood furniture in the spring

Brightening up your favourite garden rocks

Water blasting
Here’s where we abandon the lackadaisical world of pressure washing and step into some serious surface treatment via high-pressure water. Water blasting is the term I use to describe the process of removing a thin layer of material along with the dirt. By selecting a narrower nozzle and directing the attitude of the water fan with intent, we can achieve some wonderful results. Fail to adhere to the discipline the technique required, and we will have less-than-desirable results.

As water streams go, the potential of a narrow fan of racing water is one to be reckoned with. Dwell too long in one spot, and you’ll soon be replacing divots! Just like when spraying finish, we need to have the broad face of the fan perpendicular to the direction of travel. You should also keep the water spray at a constant distance from the surface, move in a uniform fashion from left to right, maintain the wand at 90 degrees, and taper the starts and stops of the spray as it comes into surface contact. So hold the wand about 45 degrees to your left, squeeze the trigger as you swing in to the right until the water is perpendicular to the surface—all while you begin to move across the surface. Taper off the right side by swinging outward at 45 degrees and releasing the trigger. This detailed process matters, because if you start and stop over the surface, or hold the wand at an angle, you’ll soon have some unsightly wood scars. This technique takes a lot of concentration and stamina, and should be practiced on a rough plank. Professionals might make it look easy, but it’s anything but.

Use water blasting for items that need aggressive cleaning:

Making pristine your new driftwood find

Renewing decking and siding surfaces for new finish

Removing moss from shingles

Cleaning masonry before patching/resurfacing

When I’m water-blasting a deck, I use a 3000 PSI washer, with the finest fan nozzle, and I keep the spray about three inches from the surface. But beware—this is enough force to damage toes. This blasting swath of water is now only about three inches wide as you move it at a rate determined by how quickly the material is coming off. Rather than just washing the deck, we are removing a few cell layers of wood, thereby returning to a pristine surface. If you’re blasting a piece of driftwood, you can dwell longer and really open up the grain. Much like sandblasting (but sans dust), water blasting is a powerful method for changing surface qualities around the cottage. Remember to wear safety glasses, and beware of blowback—you don’t want a face full of dirty water. Have a blast!