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Comment by mhb | Hacker News Reader

That isn't unique to ladders - wood for any project should acclimate to its environment (humidity) before starting construction and it doesn't take 15 years.

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Actually, the time it takes is roughly dependent on the thickness of the wood and the delta in humidity from the place where it was cut and the place where it will be used.

Typically you want to avoid wood used for ladders drying out after the ladder is put together because it will loosen the joints.

The varnish helps with this as well.

OK. And it doesn't take 15 years for the moisture content of wood in the thickness they are using for those ladders to come to equilibrium. And that is assuming that the moisture content is asymptotically approaching some target humidity. Since the humidity in San Francisco varies quite a lot the target ambient humidity is not constant.

So although they may make fine ladders, it's not because they have the wood sitting around for over a decade.

The longer you acclimate the wood, the tighter the joints are. You also are able to spot flaws in the wood. This is one of the reasons why people recover wood from old barns -- a farmer I worked for in high school was offered a substantial amount of money for wood in a Dutch barn built in the 1600's.

These guys are old-school craftsman who are obsessed with quality. Refreshing in this age of disposability.

The reason old wood is valuable is because it has characteristics that are not available in lumber harvested today. These include grain, width of planks and density. Not because its moisture content has had several centuries to change.

When you have a plank, post or beam that has stood in place in an unheated barn for 400 years, it has been subject to the vagaries and every permutation of hot & cold, damp & dry.

These cycles bring out the best and worst of the wood. Obviously you are recovering old wood in a barn for other reasons as well, but in the ladder scenario, they want top notch wood that will last. Since SFFD has ladders that have been in active service since 1919, they obviously have that down.

Undoubtedly the astrological sign of the wood is also a factor in how the wood has responded to its life experiences, but that is all irrelevant for making a ladder as long as the wood's moisture content has stabilized suitably for its target environment.

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