Can someone please explain the concept.

[Karim Sleiman]

Im currently in Sofia,Bulgaria and want to start producing and selling handmade products to sell worldwide,

theres an excellent lumber yard here called Jaf that has a great selection of almost every type of wood species.

The thing is all the killin dried wood they have is at 12 percent 11-12 apparently and thats for most places in europe according to the person there, now if i were to sell these products worldwide then how does one account for the difference in wood moisture content in different continents. in the U.S its 6-8 killin dried for example. i do have a small shop with an air conditioner thats always working i leave the temp at 20-21 degrees Celsius and i have a dehumidifier where its always set at 50 percent humidity. after reading about wood reaching its equilibrium what should it be to try and accommodate as much to all continents.

8 percent seems to be the magic number but im confused as to how to let it reach that or find the proper calculation for emc.

Thank you so much

 

[MarkAW]

It will depend on the environment the product is to be in rather than what it's sold at. Some parts of USA are very arid and some very humid - it's a big place. If expansion and contraction is factored into the design it may not be an issue. It becomes more of an issue with the larger products like furniture. If you're making tea light holders then it's unlikely to be an issue. I also imagine risk of cracking going from humid to arid environment quickly could cause cracking. 12 % MC is about the same as here

 

[Karim Sleiman]

It will depend on the environment the product is to be in rather than what it's sold at. Some parts of USA are very arid and some very humid - it's a big place. If expansion and contraction is factored into the design it may not be an issue. It becomes more of an issue with the larger products like furniture. If you're making tea light holders then it's unlikely to be an issue. I also imagine risk of cracking going from humid to arid environment quickly could cause cracking. 12 % MC is about the same as here

Hi Mark, they are small to medium items boxes, wall art book stops so on small gifts but still theres got to be a way to account for change in environment other than joinery just to be on the safe side yet how does one calculate that if your trying to sell worldwide, other than knowing where your furniture will sit and know the EMC of its final destination theres got to be a number which people go by to begin with.

 

[MarkAW]

I see what you mean. You're looking for a MC to make things at that will be least affected whether shipped to an arid or humid environment. - I've no idea on that. I imagine a lot of variables are involved, as shipping could go through both environments, different woods will have different expansion differences for the same humidity. Different joinery will fare better.

So it's not a silver bullet answer, but a best fit answer. It may be worth approaching an existing company and asking what MC do they make to.

 

[HOJ]

I would recommend getting the book by Richard Jones: Cut and Dried also known as @Sgian Dubh on here.

 

[Karim Sleiman]

I see what you mean. You're looking for a MC to make things at that will be least affected whether shipped to an arid or humid environment. - I've no idea on that. I imagine a lot of variables are involved, as shipping could go through both environments, different woods will have different expansion differences for the same humidity. Different joinery will fare better.

So it's not a silver bullet answer, but a best fit answer. It may be worth approaching an existing company and asking what MC do they make to.

your right i guess the best option is to find an existing company to check with.

 

[Karim Sleiman]

I would recommend getting the book by Richard Jones: Cut and Dried also known as @Sgian Dubh on here.

Thank you, ill have a look anything to help understand more

 

[johnnyb]

I wouldn't worry to much. Make it and sell it. Any returns(if there is any) just send new or discount. 12% is dry enough.

 

[Sgian Dubh]

The key is understanding how wood behaves as it changes moisture content. When you understand that you have to learn how to make things in such a way that allows the wood in products to expand and contract without being detrimental to the structural integrity of the product, whether that be small items or large items. The reason for saying that is because wood is always adapting to the relative humidity (RH) in which it finds itself, and RH changes constantly, i.e., by the hour, by the day, by the week seasonally.

It's not a problem if you build an item out of wood that's, for example, at 13% MC, so long as you allow that the item may experience conditions that change its MC to somewhere in the range of ~5 - 15% MC, or perhaps an even greater range, all depending on the environmental conditions the product experiences.

In your case, the small items you describe aren't very likely to experience a great deal of troublesome dimensional change between those numbers I gave earlier, i.e., ~5 - 15% MC, which is what they're most likely to experience.

On the other hand, if you really want to get a very good handle on wood movement it wouldn't hurt to read some reliable and reputable sources on wood science or timber technology. Slainte.

 

[Karim Sleiman]

I wouldn't worry to much. Make it and sell it. Any returns(if there is any) just send new or discount. 12% is dry enough.

Johnny, I want that mindset.

 

[Karim Sleiman]

The key is understanding how wood behaves as it changes moisture content. When you understand that you have to learn how to make things in such a way that allows the wood in products to expand and contract without being detrimental to the structural integrity of the product, whether that be small items or large items. The reason for saying that is because wood is always adapting to the relative humidity (RH) in which it finds itself, and RH changes constantly, i.e., by the hour, by the day, by the week seasonally.

It's not a problem if you build an item out of wood that's, for example, at 13% MC, so long as you allow that the item may experience conditions that change its MC to somewhere in the range of ~5 - 15% MC, or perhaps an even greater range, all depending on the environmental conditions the product experiences.

In your case, the small items you describe aren't very likely to experience a great deal of troublesome dimensional change between those numbers I gave earlier, i.e., ~5 - 15% MC, which is what they're most likely to experience.

On the other hand, if you really want to get a very good handle on wood movement it wouldn't hurt to read some reliable and reputable sources on wood science or timber technology. Slainte.

Hi Sigian, yes absolutely agree, i am accounting for movement, box tops bottoms for example but always thought even if the box sides are wrap around and move together while it is at 12 percent moisture and then ends up in a dry environment where moisture goes down for example wouldn't the sides themselves on the joints be affected as-well or am i going crazy overthinking.

 

[profchris]

For most practical purposes you can ignore shrinkage along the grain, it's so small. Cross grain is the issue, different species move different amounts.

So your box gets taller or shorter, but if the sides are the same species they move together. No stress on the joints.

Tops and bottoms of boxes are the issue, as the sides resist cross grain movement. That's where you design in an allowance if needed.

 

[johnnyb]

Yes crazy overthinking. American oak is the worst wood I've ever used its just so dry. Cedar the same. 8% is to dry imho. It kills the nature of the material. Not unlike accoya. I saw accoya up make a part then lol and behold I can snap it with my fingers. It's brittle and dry.

 

[Karim Sleiman]

For most practical purposes you can ignore shrinkage along the grain, it's so small. Cross grain is the issue, different species move different amounts.

So your box gets taller or shorter, but if the sides are the same species they move together. No stress on the joints.

Tops and bottoms of boxes are the issue, as the sides resist cross grain movement. That's where you design in an allowance if needed.

Hi Profchris, You helped with another post, thanks again for the info

 

[profchris]

You're welcome. There are shrinkage tables for common species online, worth checking out for design. For example, an oak back on a guitar might move 4% of its width, mahogany half as much. I dome backs to allow for this, and oak would get a higher dome.

 

[Karim Sleiman]

Yes crazy overthinking. American oak is the worst wood I've ever used its just so dry. Cedar the same. 8% is to dry imho. It kills the nature of the material. Not unlike accoya. I saw accoya up make a part then lol and behold I can snap it with my fingers. It's brittle and dry.

definitely crazy i am lol the more i read and learn the more i feel overwhelmed, Im using euro oak and walnut their beautiful but yes oak is very susceptible to chipping its more difficult to work with, but cedar thats new i always thought its sort of like spf lumber pliable in a way soft buuut yes 8 percent is too dry i 100 percent agree since i only have 12 percent

 

[Karim Sleiman]

You're welcome. There are shrinkage tables for common species online, worth checking out for design. For example, an oak back on a guitar might move 4% of its width, mahogany half as much. I dome backs to allow for this, and oak would get a higher dome.

ill definitely account for that though thats interesting guitar back i always thought electric guitars are a solid pice with a different wood species for the neck and the classic guitar veneered.