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Add approx. 5oz. acid to each gallon of water.
Citrus Acid- Used on hardwoods.
Oxalic Acid- Primarily used on redwoods.
Phosphoric Acid- Used when an unfinished deck has turned "gray".
I'm very hesitant to suggest a pressure level when it comes to cleaning decks because it's just so subjective. One deck will have harder wood than another and
other decks will have softer and harder areas on same deck. In this respect only experience can really guide you. As a general rule of thumb use least amount of pressure that will get job done.
Test pressure on an inconspicuous area of deck. The underside works well for this
Excessive pressure will cause a deck to "furr".This is appearance of small hairlike fibers protruding from wood.. Your customers will not like way this looks and light sanding will be required to correct this condition.
Ready, Set, Go!
Soak area to be cleaned thoroughly. This serves several purposes but most importantly, deck must remain damp throughout entire cleaning process.
Apply cleaning chemical with applicator of your choice.When just starting out a pump up type sprayer will work nicely. Allow your chemical to dwell for 15-20 minutes. Do not allow to dry. If necessary spray more water or reapply chemical.
If you've sufficiently dampened deck and haven't dawdled this shouldn't be a big problem.
Clean. Remember when cleaning use low pressure. Never clean against grain or accross grain. Feather each pass. The pressure used should be enough to remove dead wood but not enough to cause "furring" Experience will be your best teacher.
Rinse deck thoroughly removing all chemical. Apply nuetralizer/brightener solution, wait 10-15 minutes and rinse well again.
If you are going to seal wait 24 hours if not 48. If you chose your day well rain won't become a problem.
Sometimes "furring will become apparent even at low pressures. These short hair like fibers are result of a "tearing" action on wood. These will probably be gone in 2-3 weeks but your customer will want them gone sooner than later. Give them a light sanding with a bronze metal scrubbing pad. Use bronze, steel wool can leave rust stains.
What not to leave behind
Here is a general list of things to bring to your job site. Some of this may not apply to you. The point is to always work with a job list to avoid embarrasment or expense of missing that tool you need right now.
Pressure Washer- Cold water gas machine 5.5-11HP commercial grade unit.
(Hot Washers are also used but at very low temperatures not
Hoses- Sufficient lengths of both pressure hose and supply hose.
Brooms/Blower- A stiff bristled push broom (not metal) and/or a gas powered leaf
Chemical applicator - Pump-up type sprayer or Flo-Jet type sprayer
Mixing Buckets - 2or3 5 gallon plastic mixing buckets.
Mixers- Drill type chemical mixer.
Respirator- Cartridge type with spares
(When working with high caustics and acids)
Face and Eye Protection- Some type of helmet with face shield.
Cordless Drill- With phillips screwbit and chuck large enough to accomodate
Hammer- If nails are required.
Deck Screws, Nails and Bolts- As required, use galvanized only.
Duct tape, Clear plastic sheeting,Cardboard- To protect areas
Extension Cords- Must be adequate length and gauge. 12 gauge minimum.
Electric Rotary Sander- With 60 and 80 grit sandpaper
Knee Pads- You didn't think you'd always be standing when sanding did you?
Remember practice makes perfect get out there and start learning.
Randall Madon is the founder and president of ATT Pressure Supply along with a new educational resource site The-Power-Washer-Advisor.com Learn More