How to Finish Decks and Porches

The deck you see here I built last summer. It has pressure treated decking, cedar posts and railing with copper balusters. We allowed the deck to dry out and age a season as I do not like the look of new deck wood but prefer a little bit of weathering to match our 1892 home. Here is how we proceeded.

For this home improvement project, we first blew the deck boards clean with forced air from an air compressor. Blowing out all the leaves and debris between the boards. Since I like the color a little weathered there was no need for pressure washing or chemicals to clean the deck. However I will outline the process. Clean the deck with a pressure washer and deck cleaner. Set the pressure washer to a low pressure setting so as not to damage and fuzz up the wood.


Wash the dirt and grime off. At this point if the deck surface is too gray or weathered for your liking you could use a deck wash from the Hardware store or use oxalic acid to bleach the gray. Follow the direction for oxalic acid on the product page. 

Once the deck is dry you are ready for the next step. If you have reoccurring green mold issues you may want to treat the wood grain at this time before the Pure Tung Oil finish is started. To help control and kill mold I recommend using TimBor Wood Preservative.

Once TimBor Wood Preservative is sealed into the wood it will not come out unless the finish wears away. Most instructions to clean wood decks recommend killing the mold with bleach and water. While this works to kill the mold on the surface and temporarily makes the wood look clean, the mold is usually back in one season because it has not been killed in the wood just on top. Adding TimBor Wood Preservative sealer into the wood with Outdoor Defense Oil  provides better long term protection. Apply TimBor Wood Preservative if necessary and allow drying.

We are now ready for the Outdoor Defense Oil made with Pine Solvent. You should check the weather for the next few days to be sure rain is not in the forecast. The wood should be dry before application, so the oil and solvent can soak into the wood. A little dew in the morning after application will not hurt anything. The oil should be applied in the shade or cool of the day (no direct sun). Direct sun can quickly polymerize the oil and leave a frosty finish. On our wood deck we applied two coats of Outdoor Defense Oil. Being that the wood aged a season, it was pretty absorbent and drank the finish right up. Two coats were applied in succession. No waiting over night, as the first coat was drawn into the wood the second coat was applied. All of the oil and solvent soaked in, a third coat could have been applied but due to time constraints we stopped there.

Allow the oil and solvent to soak for 40 minutes to an hour. What ever has not soaked in wipe up with clean “T” shirt material. Allow to dry for a day or two before heavy use. All the oil should soak into the wood. Do not let oil lay on top of the wood and dry. This will make a rough deck finish that has a slight frosty look. If a one to one mixture is not soaking into the wood, the oil needs more Citrus Solvent.

On the contrary if your wood is really dry and it will absorb the Pure Tung Oil straight, you can apply it first then follow up with Outdoor Defense Oil.

There are many advantages that Outdoor Defense Oil  offer. If your wooden deck is made of the old arsenic laced pressure treated wood, Outdoor Defense Oil  will seal the chemical into the wood. Also the Pine / Citrus blended solvent kills bugs and ants that might be hiding in the cracks. While Outdoor Defense Oil seals and protects the wood it will not blister and peel so future application just requires a quick cleaning then apply more.

Outdoor Defense oil does contain  Zinc as a UV ray inhibitors so it does naturally resist mold and mildew. It will also resist graying as long as enough finish is maintained on the wood.

Each gallon of Outdoor Defense Oil cover 400 square feet one time. 

Well, one more DIY project complete. The deck has been a wonderful addition to the house and we all have been enjoying it thoroughly.

-Dwayne Siever



Brushing or rolling works well. The glossy area is where the oil has not completely penetrated, allow minimum 40 minutes for oil to soak before wiping off.