Here, where the humidity is 90-100% for over half the year and so mold is routine, people have various solutions. I was surprised to find a neighbor also charring wood (with a dragon torch, as I have) to keep mold from growing on it. He was using natural wood, I was using lumber. Is there merit to this approach?

And while reading about beeswax, I had a thought. If it naturally suppresses mold, why not char-finish your exposed wood, then lightly coat it with beeswax while it's still hot? Just rub the bar on the
heated spot. Obviously, it can't be in a spot where rodents can get to it. In late winter beeswaxed wood must be like buttered bread!

I've been treating mold with Concrobium mold killer then painting with Kilz, but it'd be nice to crib together some less manufactured method...or revive a traditional method. Concrobium, I hasten to point out, has as its active ingredient sodium carbonate, that is, washing soda. At $30 a gallon, I've wondered if I can't just make a solution of washing soda and apply that. I'll probably try it on some uninhabited outbuilding and post results.

What you're doing sounds similar to Shou Sugi Ban, a method of Japanese wood preservation. A friend of mine uses it in her art, and many people have turned to it for similar reasons as you describe.

It has been discussed on this site.

Basically, a thick layer of char is a great barrier to deeper penetration by anything that wants to eat your wood. I might choose something less tasty-smelling than beeswax, something like linseed oil, maybe, but the method certainly works.

-CK

Hi Chris, thanks, I am aware of shou sugi ban! It is an awesome thing aesthetically and practically, when you have time, patience for process and wood that is not built into something already. In fact torching wood with a dragon torch and then applying linseed oil, or not, struck me as a lazy shou sugi ban technique, which i absurdly called hobo sugi ban in a fit of marketing dysgenius after burning a bunch of nascently-moldy wood crates and linseed oiling some. None show evidence of mold, but how could they, black mold being the same color as charred wood.

I haven't been able to find proof that fire kills mold and/or deactivates spores. Annoyingly, most of what I've read about SSB online has been preoccupied with its aesthetics. I have a feeling I will have to conduct these experiments on my own with whatever procedural rigor I can manage. Another finding I hope I can post here someday.

Chris Kott wrote:What you're doing sounds similar to Shou Tsugi Ban, a method of Japanese wood preservation. A friend of mine uses it in her art, and many people have turned to it for similar reasons as you describe.

It has been discussed on this site.

Basically, a thick layer of char is a great barrier to deeper penetration by anything that wants to eat your wood. I might choose something less tasty-smelling than beeswax, something like linseed oil, maybe, but the method certainly works.

-CK

I wouldn't recommend linseed oil, it actually feeds mold and fungus, pretty much any vegetable oil will.  It's even worse if you use linseed oil in humid environments.

What about pitch? like how they cover birtch bark canoes

Good to know about vegetable oils, Peter. Thanks.

-CK

Hi Christine, I've thought of that before, and it seems a really great idea! In fact it's probably worth going forward with if I/we can just figure out efficient extraction of pitch.

I've been told that I can put chunks of fresh-cut conifer wood in a pot in a hot fire, and the pitch will boil out of them. Pitch can also be bought at seed & feed stores that sell horse supplies (Wilco would be my closest, or maybe Tractor Supply), because it's used to dress horse wounds. A boat restorer told me he makes a traditional Scandinavian seal out of turpentine, linseed oil and pitch...that's a formula I plan to try on tool handles. It might also be worth testing against mold. I'll post results when I've got em!