Refinishing decks with pine tar and raw linseed oil is a supier way to preserve your deck using chemical-free products that were meant for wood. No need to power wash, which puts too much water into the wood and ultimately damages when finished with acrylic products that trap the moisture inside, creating mold and rot. My method is to first clean the deck with linseed oil soap, then apply the raw linseed oil and pine tar mixture. One coat is usually one coat is enough. This works best when the deck has not been previously painted or stained prior. Light sanding may be required to allow the products to fully penetrate into wood.