Jay C. White Cloud wrote: ... For method...
experimentation is always my first suggestion, as your wood and available tools may vary.
Jay C. White Cloud wrote: I would suggest a good oiling with one or a blended mix of pine tar oil, flax oil, tung oil, etc. Do this to both sides and before charring with this species.
Bill Bradbury wrote:I absolutely LOVE this treatment, but I char the wood after assembly. I use locally harvested Douglas Fir that has only aged a few months, so it still has some moisture to it(20% or so). Then I use a propane weed burner that has a control valve to char the entire structure. I then sand lightly and stain with Penofin rosewood oil. I have attached a photo of the pergola and greenhouse I built last summer on the back of my house.
This looks beautiful! I would love to do this to finish my log home but don't know if the time aspect would be practical.
Approx how long are you holding the torch to each portion of wood to achieve this effect?
Does this "half char" still achieve a good level of rot prevention or is it mainly for aesthetics if you don't fully char?
Jay C. White Cloud wrote:You may do it after, yet I have found that pre oiling gives a more even charr and it also draws the oil deeper into the wood it seems...
Laura Sweany wrote:I am planning to install 1"x 6" fir boards as a temporary (1-3 years) flooring in my single-wide mobile home, and I love the dark color of this burning technique. What would I finish it with to make it durable as a floor? I've done every search I can think of and haven't come across any threads that address natural finishes for wood floors.
I would just do the faces and sides, but it won't hurt to do all six sides.
Should I worry about charring the backs of the boards, or just the faces exposed to sunlight? (I suppose insect resistance would be the primary goal here? and maybe unnecessary as this is over a rainscreen?)
The oil is applied(I use a 4" brush) immediately after charring and sets the char. If you don't oil, the char will come off on your hands while you install them, also they will not last as long in the elements.
many of you mention rubbing in oil after charring--what's the idea behind this? Can I safely skip (I'm trying to limit work for myself, as this is already a big pile of lumber?
When you burn wood, the volatile compounds in the wood combust first. This is what you wish to remove. So, put the burner close to the wood, but at a back angle and start slowly traveling down the board. At first the wood just deflects the flame from the burner, but when the temperature is right for this treatment, the wood will burst into flame. That means move a little down the board, maintaining that burst as you go along. The back angle will keep the burn going for a little longer and you should end up with a very black board that is lightly covered in char. Don't sand it, just oil. I love Penofin red label for the UV protection.
Given my motives, how much char should I put on the boards, at minimum? Blacken the surface? Get a 'gator skin' depth? Does anybody have any anecdotal evidence on longevity vis. burn level (I saw a comment that there's no hard evidence, but figure it's worth another ask)?