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 wood but prefer a little bit of weathering to match our 1892 home. Here is how we proceeded.
First we blew the deck 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 to pressure wash or chemically 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 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 at this time before the Pure Tung Oil finish is started. To help control and kill mold I recommend using PC Wood Guardian.
Once PC Wood Guardian is sealed into the wood it will not come out unless the finish wears away. Most deck cleaning instruction recommends killing the mold with beach 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. PC Wood Guardian sealed into the wood with Pure Tung Oil provides better long term protection. Apply PC Wood Guardian if necessary and allow drying.
We are now ready for the Pure Tung Oil and Citrus 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 deck we applied two coats of Pure Tung Oil and Citrus Solvent in a one to one ratio. 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 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 that way. Please note, even if Pure Tung Oil and Citrus Solvent are over applied and allowed to dry on the surface it will not turn black like Penofin oil finish.
There are many advantages that Pure Tung Oil and Citrus Solvent offer. If your deck is made of the old arsenic laced pressure treated wood, Pure Tung Oil will seal the chemical into the wood. Also the Citrus solvent kills bugs and ants that might be hiding in the cracks. While Pure Tung Oil seals and protects the wood it will not blister and peel so future application just requires a quick cleaning then apply more.
Even though Pure Tung Oil does not contain UV inhibitors 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 Pure Tung Oil will cover 400 square feet. Add a Gallon of Citrus Solvent to the Pure Tung Oil, you now can cover 800 square feet.
Well, one more project complete. The deck has been a wonderful addition to the house and we all have been enjoying it thoroughly.
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.