Tung oil is another alternative. I know it can be used for things like wooden cutting boards, but like any cutting board with washing and use it requires reapplication depending on the amount of use it gets. Perhaps it may work for you, but I'm not sure about mildew or how often it would need reapplication with regular rain.
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
Location: Limestone, TN
posted 2 years ago
I looked up tung. Pretty heavy duty. Needs a pigment as well. But I found canola oil and vinegar apparently no pigment needed. Also soy is a possibility. Haven't researched yet. Thank you.
If there's a good stand of birch on your homestead, I recommend rendered birch oil as an exterior wood preservative. I coated the 1X6 reclaimed yellow pine esterior decking boards I have before I installed them, and have reapplied the oil every other year for 18 years; the wood is well preserved and has a wonderful honey color. After application, it will remain tacky for two or three days depending on temperature and humidity conditions. I always apply the oil in October or November here in Massachusetts, and it takes two days to cure. Birch oil extraction is sustainable and easy. Water beads up on birch oil, and it has a marvelous fragrance. I also use it to waterproof leather goods and canvas tarps. There are many articles and videos on how to extract and render the oil from different parts of the tree, but I always use the bark. There are also several informational resources online regarding sustainable birch bark harvesting.
Location: Limestone, TN
posted 2 years ago
Actually there is a large river birch beside the deck. I am right now cutting english ivy off of it, again. Frustrated cuz I love this tree and I can't keep the ivy off. But that's a different topic. I love birch and love the idea of the oil. Yet, I don't think this one tree would be sufficient. Thank you, Brett. will research this. interesting.
Neat! I wonder if that method for rendering birch oil could be retrofitted to a jolly rogers RMH? I've wondered the same thing about making Sepp's bone sauce that way. Seems like a good use of the extra barrel while still converting some of your fuel source to biochar...
"The highest function of ecology is the understanding of consequences."
"Cultivate gratitude; hand out seed packets"
I make soap from biodiesel waste. It was reacted with KOH (Potassium hydroxide) but none remains in the oil which has a lot of glycerin.
This spring I spilled some on the deck, so spread it out on the wood. Now several months later the oil has permeated the wood and looks great. I plan on using this oil to coat the remainder of the deck. It does leave the wood dark, but to me that's fine. The area that does have the oil shows the water beading up. The dogs never lick it nor does it track inside the house.
Biodiesel makers often will give this oil away for free. Usually they pack it in 5 gallon plastic containers. That much oil will go a long way. Try pouring it into a bucket and then using a sponge mop as an applicator.
1 part pine tar
3 parts boiled linseed oil (or raw)
1 part turpentine
This works well for dry softwoods: cedar, yellow pine, etc. Apply 2-3 initial coats, then one coat per year.
It will turn black with exposure to the sun. This protects the wood from UV damage.
Selecting BLO or raw depends on your climate, as well as the material available. Most boiled linseed oil sold in the states consists of raw linseed oil with heavy metal dryers added. Check solventfreepaint.com for alternatives, or make your own.
Climate-wise, consider raw if you live in a dry climate. I live in the southeast where raw would never dry.
I'm a cabinetmaker with a predilection for old-fashioned low tech stuff. I also don't like too much extra work, so I use Penofin for matte finish outside woodwork: full disclaimer.
Jane Southall wrote:What is the best natural oil for waterproofing a deck, on a budget? Thanks.
I am sure that you can also come up with different materials more available in some parts of the the world and not others. I am a member of the Raised Bed GardenFacebook Group and saw a nice garden set up with mostly poplar 2 X 10 lumber - but I noticed it had a cool amber/greenish tinted oil look to it. Asking the designer of the garden and he advised that where he lives in California that he can get all the avocado oil that he wants for next to nothing and he uses it for treating the wood on all his raised bed garden jobs he completes for people. Not unlike the response to your query someone mentioned the birch bark oil, but again it needed to be at least regionally local to be of cost benefit. I for one would like to see how your deck turns out.
as far as finishes go, soy will not work in a really rainy environment, I have used it and it mildews horribly.
tung oils beautiful finish is much appreciated, but you must use some kind of citrus oil to help in the drying, put it on thin and really buff it in. you will need two or three coats.