Rainy weather and woodworking.

[Guest Screamer]

This question bothers me a long time. Is it advisable to do woodworking in rainy weather when the humidity is high?

Especially joinery such as tenon and mortising, dovetails etc. We all know that wood moves as the seasons change. Will the joint become less effective when the weather dries and the wood shrink again. And the same apply to dry weather. Will the joint crack if it expand again in dry weather? I might sound silly and paranoid , but I think I've got a valid question here.

PS

This forum is really very informative.

Greetings from South Africa.

Johan

[Beechwood Chip]

And the same apply to dry weather.

What is this "dry weather" of which you speak?

Chip from Philadelphia

[joestyles]

What I know is that wood moves. Where I live it rains lots in the spring (now) and not so much in the summer. The shop is about 100 meters from a large body of moving water (Columbia River) this makes wet rainy days very humid and dry hot days not so dry. How this effects me is Kiln dried soft wood tends to pick up moisture in my shop hard wood does the same but at a different rate. Drying wood in my shop takes time. I think you need to look at your environment inside and outside of your shop, what your stock is like, and how rain might effect your stock. One way I would do this is pick some of my driest scrap that has been there for a long time and then on a rainy day cut it and see what happens. Maybe make a few joints out of scraps and see how they respond. This way you will have a good idea for your own environment. For myself a wet rainy day is no big deal most times but as I said if I was doing something with kiln dried wood that was very dry I would likely hesitate on a rainy day but I would assume if it has been there for more than a few weeks the moisture content is already higher than it was.

Sorry for the long post. In short I would experiment with the condition so I would know what is likely to happen. If you live on the coast and it rains most of the time it would not matter much until you sent a piece to a low humidity environment or if your shop were in the desert and you sent a piece to live on the coast.

[Vic]

What I know is that wood moves. Where I live it rains lots in the spring (now) and not so much in the summer. The shop is about 100 meters from a large body of moving water (Columbia River) this makes wet rainy days very humid and dry hot days not so dry. How this effects me is Kiln dried soft wood tends to pick up moisture in my shop hard wood does the same but at a different rate. Drying wood in my shop takes time. I think you need to look at your environment inside and outside of your shop, what your stock is like, and how rain might effect your stock. One way I would do this is pick some of my driest scrap that has been there for a long time and then on a rainy day cut it and see what happens. Maybe make a few joints out of scraps and see how they respond. This way you will have a good idea for your own environment. For myself a wet rainy day is no big deal most times but as I said if I was doing something with kiln dried wood that was very dry I would likely hesitate on a rainy day but I would assume if it has been there for more than a few weeks the moisture content is already higher than it was.

Sorry for the long post. In short I would experiment with the condition so I would know what is likely to happen. If you live on the coast and it rains most of the time it would not matter much until you sent a piece to a low humidity environment or if your shop were in the desert and you sent a piece to live on the coast.

Hi Joe. Are you in the Portland area? It sounds like you may be. I'm over in the Tri-Cities. I'm right on the Columbia, but it's extremely dry here most of the year.

[Guest Screamer]

What is this "dry weather" of which you speak?

Chip from Philadelphia

Hi

By dry weather I means "normal" weather. I live in the highveld area, which is 1300 meters above sea level. Here it is a typical summer rainfall season. It tends to rain a lot this year. More than other years. With fall approaching very fast, it gets colder and we had a lot of rain the previous days. Maybe it is a good idea too join test pieces ans see what happens.

Thanks for the replies.

[tim0625]

What is this "dry weather" of which you speak?

Chip from Philadelphia

Yeah, I guess "dry" is relative. Here in coastal SC, we have a lot of 90+% humidity. It's like Joe said, 'wood moves' as does metal or anything else. Look at the huge expansion joints in a bridge. Even concrete expands and contracts but my experience Johan is that the minor movement of wood is not enough to overcome the strength of the quality glue joint. Rain and temperature just affect the drying time some. What would you say is your average humidity in SA?

[Guest Screamer]

Yeah, I guess "dry" is relative. Here in coastal SC, we have a lot of 90+% humidity. It's like Joe said, 'wood moves' as does metal or anything else. Look at the huge expansion joints in a bridge. Even concrete expands and contracts but my experience Johan is that the minor movement of wood is not enough to overcome the strength of the quality glue joint. Rain and temperature just affect the drying time some. What would you say is your average humidity in SA?

Hi Tim

It depend what time of the year it is. In the summer the humidity average between 40% and 80%. In the winters it more like a constant 20% to 40%. Luckily, because of the high altitude, the high humidity does not cause discomfort. But at the coastal regions, like Kwazulu Natal, it can get very bad.

Johan

[joestyles]

Hi Joe. Are you in the Portland area? It sounds like you may be. I'm over in the Tri-Cities. I'm right on the Columbia, but it's extremely dry here most of the year.

Hi Vic I'm in Trail BC and this is normally a dry zone but the river is close and the conditions at my shop tend to be helped in the dry times by the river being so close. It also makes the wet times a little wetter. If I were a few hundred yard further and a bit higher away from the river (banks are steep here) I would have different conditions more like yours.

[joestyles]

Johan seems like you are on the right track. Your humidity does not change quickly I bet except when it rains suddenly. Time is a huge factor in all this too. How long something is exposed to high humidity will be mitigated by how fast the material can absorb moisture. Spruce in my shop takes it up pretty fast but just one day of rain is not enough to change it lots a week of rain after a dry several days of dry weather will definitely move it lots. My limited supply of hard woods however seem to do better for moisture, they seem to be more stable under changing moisture conditions taking up or losing moisture much slower than the soft woods. The upside is that if I cut lumber locally I can season it in my shop by taking advantage of the slow dry times in the spring and fall. I get local fruit tree wood and some black locust this way. I am trying to spalt some apple wood just now but that is actually in the shade outside just now. One down side for me is particle board and MDF do not fair well in my shop they tend to swell and then break apart over a short time (6 months or so) Plywood seems to do ok but it is more tolerant of ambient moisture changes.

[Guest Screamer]

Johan seems like you are on the right track. Your humidity does not change quickly I bet except when it rains suddenly. Time is a huge factor in all this too. How long something is exposed to high humidity will be mitigated by how fast the material can absorb moisture. Spruce in my shop takes it up pretty fast but just one day of rain is not enough to change it lots a week of rain after a dry several days of dry weather will definitely move it lots. My limited supply of hard woods however seem to do better for moisture, they seem to be more stable under changing moisture conditions taking up or losing moisture much slower than the soft woods. The upside is that if I cut lumber locally I can season it in my shop by taking advantage of the slow dry times in the spring and fall. I get local fruit tree wood and some black locust this way. I am trying to spalt some apple wood just now but that is actually in the shade outside just now. One down side for me is particle board and MDF do not fair well in my shop they tend to swell and then break apart over a short time (6 months or so) Plywood seems to do ok but it is more tolerant of ambient moisture changes.

Thanks for the reply Joe. I've got lots of Bubinga, some Red Oak (from good ole USA) and some local timber. Like Kiaat (Muminga) and Yellow wood. The Bubinga is relative cheap here in South Africa. I found that the Red Oak tends to absorb moisture the most. Maybe it is from the fact that it has a very course grain. The Bubinga planks stays relative stable. The Kiaat planks are like Walnut with a finer grain. And maybe a bit darker.

Johan

[Lawrence Brown]

One thing you could try if you're curious as to how much your wood is moving is to get a metal or plastic ruler (so it's not affected by the humidity) and attach a piece of the wood you're curious about to one end. make sure it's oriented so that as the wood expands it travels down the ruler. Make a mark on the ruler when it's been dry for a while and then look at it when it's been raining and see how much it's moved.

I wouldn't use it for precise calculations, but it'll give you a general idea of what's happening and it's kinda fun. Also remember that the bigger the piece of wood, the more total movement, so if you are using a small piece of wood (like an inch or two across), you won't see much movement.