4 ms·

The material they show in the article is massive. Thick, long and heavy. Even if there are kilns big enough, the wood would no longer be straight after a fast k

by exDM69 8y ago

The material they show in the article is massive. Thick, long and heavy. Even if there are kilns big enough, the wood would no longer be straight after a fast kiln drying. A 50' 3x3" board would be twisted and bowed so much that the ladder would be a spiral staircase. It doesn't matter for 20' 2x4 destined for a construction site. Even if the wood was kiln dried, it would still have to acclimatizate for months or years before it would be at a stable 13% humidity of San Francisco.

DannyBee 8y ago
"The material they show in the article is massive. Thick, long and heavy. Even if there are kilns big enough, the wood would no longer be straight after a fast kiln drying." This is not true, depending on timeline. It's true of the production rate kilns, and as you say, it doesn't matter for construction lumber, which is why they do it. But assuming 3+ years to dry your 3x3" board, even doing it in a kiln at a 6 month rate (or whatever) would be a vast improvement, and would basically not bow or check. Again, there is actually a vast amount of research on drying schedules vs defects and how to optimize for whatever you want for a given wood species. As for kiln size, again, solar kilns are quite trivial to build for basically any size or shape, and can easily be temperature controlled for something like this. (and they could easily build a kiln in the space they have shown in that article) To whit: I've built a solar kiln in maryland for 30+ ft boards before, and cost of materials was < $1000. (I used to buy lumber from a guy who was responsible for handling downed trees for some cities in northern virginia, and he used to saw and sell the lumber. He did the nail removal, etc) "Even if the wood was kiln dried, it would still have to acclimatizate for months or years before it would be at a stable 13% humidity of San Francisco." Why? You can just stop drying it at 13% (instead of the 7-8% that is normal).
- coryfklein 8y ago
  These ladders last decades so presumably most of the shop work is in maintaining existing ladders, not in pumping out lots of new ones. It would be a waste of time and money to kiln fire the wood for 6 months when you can just order it 1-2 years in advance and leave it in the corner to accomplish the same purpose.
  - DannyBee 8y ago
    "These ladders last decades" Then literally this entire process is a complete waste of time, because they will never stay at any moisture content over this time period.
    - loco5niner 8y ago
      I believe the article said the ladders were sealed with multiple coats.
    - coryfklein 8y ago
      The point is to bring them to the natural moisture content due to the average San Francisco humidity. Once they are there they will stay there because the average humidity is relatively constant.
      - DannyBee 8y ago
        I understand the goal (I've been woodworking for 20+ years). Wood does not react to average humidity, it reacts to current humidity. Defects occur because of sudden changes the wood cannot "handle" (IE it's not elastic enough, etc), not because the average is too high or low. Over decades, the likelihood of that happening seems quite high.
deleted 8y ago
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by exDM69 8y ago

DannyBee 8y ago

"The material they show in the article is massive. Thick, long and heavy. Even if there are kilns big enough, the wood would no longer be straight after a fast kiln drying." This is not true, depending on timeline. It's true of the production rate kilns, and as you say, it doesn't matter for construction lumber, which is why they do it. But assuming 3+ years to dry your 3x3" board, even doing it in a kiln at a 6 month rate (or whatever) would be a vast improvement, and would basically not bow or check. Again, there is actually a vast amount of research on drying schedules vs defects and how to optimize for whatever you want for a given wood species. As for kiln size, again, solar kilns are quite trivial to build for basically any size or shape, and can easily be temperature controlled for something like this. (and they could easily build a kiln in the space they have shown in that article) To whit: I've built a solar kiln in maryland for 30+ ft boards before, and cost of materials was < $1000. (I used to buy lumber from a guy who was responsible for handling downed trees for some cities in northern virginia, and he used to saw and sell the lumber. He did the nail removal, etc) "Even if the wood was kiln dried, it would still have to acclimatizate for months or years before it would be at a stable 13% humidity of San Francisco." Why? You can just stop drying it at 13% (instead of the 7-8% that is normal).

coryfklein 8y ago
These ladders last decades so presumably most of the shop work is in maintaining existing ladders, not in pumping out lots of new ones. It would be a waste of time and money to kiln fire the wood for 6 months when you can just order it 1-2 years in advance and leave it in the corner to accomplish the same purpose.
- DannyBee 8y ago
  "These ladders last decades" Then literally this entire process is a complete waste of time, because they will never stay at any moisture content over this time period.
  - loco5niner 8y ago
    I believe the article said the ladders were sealed with multiple coats.
  - coryfklein 8y ago
    The point is to bring them to the natural moisture content due to the average San Francisco humidity. Once they are there they will stay there because the average humidity is relatively constant.
    - DannyBee 8y ago
      I understand the goal (I've been woodworking for 20+ years). Wood does not react to average humidity, it reacts to current humidity. Defects occur because of sudden changes the wood cannot "handle" (IE it's not elastic enough, etc), not because the average is too high or low. Over decades, the likelihood of that happening seems quite high.

deleted 8y ago

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