Boards curving...Help!!

[chypes]

I purchased some of Home Depots "Select Paine" Boards to run a few projects.
.750'' x 12'' x 6-8' Select Pine

I made extra effort to ensure the boards I purchased were straight and flat and clean, etc.

After carving on 18'' long section with 12'' of width, I noticed the board had curved slightly down the entire length of board. Then, upon inspecting my other boards of the same species and sizes, they too had a slight curve down the entire length.

Questions:

Is it the South Texas heat and humidity causing this?

Can I do something to avoid this from happening BESIDES working in an air conditioned shop?

Is there a technique to re-work the wood to remove the curve? I did notice that a couple of the pieces did revert back to their original flatness once I brought them inside my house for a few hours exposed to nice, cool, air conditioned temps.

I live in Texas and it gets hot. I cannot afford to have boards curving up on me every time it gets a little bit hot in my shop.

This is "SELECT PINE" ....I would think it has been milled, cured and treated efficiently so as to avoid this type of issue. What am I missing?

[Bigtyme]

Humidity is one of the greatest factors in wood movement, but another is how it was cut from the log. It is probably "flat sawn" which yields the most board material but is the most unstable even in a controlled environment. The next level is "rift sawn" and the most stable (but the most costly) is "quarter sawn". There are a number of great articles on the characteristics of each if you Google them. Once the wood cups (and stays that way) it is very difficult to straighten out. It typically requires a jointer to flatten it out. I would suggest finding a good lumber yard other than a big box store. They can help you find the right pieces and they are typically less expensive than the big box guys. I plan to stop at my local yard today to get a piece of 5/4 maple which will cost me about 1/3 of the price in a big box (if I could even find 5/4 at a big box store)....

[FWMiller]

The are many factors that affect wood movement but the bottom line is it can't be completely avoided. To minimize it you start by selecting boards less likely to cup or twist. You need to pay attention to the grain orientation regardless of how flat the board is when you buy it. There are many places to read up on this. Gluing narrower boards to make a wide one is usually more stable. If you have jointer and planer you can buy lumber a little thicker than needed, let it sit in the shop for a week to adjust and then joint and plane to final dimensions. It doesn't prevent future movement but it will keep it flat in the shop environment while you are working on the project. Assuming your project doesn't span seasons...

[RogerB]

I never use wide boards. I cut in strips no more than 3 inch and rotate the grain. To bring back a board that had warped that has been carved you can place in front of a heater on the warped side. It will dry the one side and pull it back. After it is flat seal the hole thing.

[aokweld101]

I have the same problem living just 5 mins. from the gulf I have found out the best way for me to fix a cup board is to fasten it to a half inch 4' x 8' metal table that I built.. me being a welder I needed a good table to weld on and to clamp metal too.. I know not everyone has a table like that in there shop but it is my fix.. clamp it down for a day and good as new.. carve and seal and good to go

[chypes]

I have the same problem living just 5 mins. from the gulf I have found out the best way for me to fix a cup board is to fasten it to a half inch 4' x 8' metal table that I built.. me being a welder I needed a good table to weld on and to clamp metal too.. I know not everyone has a table like that in there shop but it is my fix.. clamp it down for a day and good as new.. carve and seal and good to go

We live right on the Gulf in Texas so we are learning that the humidity can be a pain in the *** in this business. I had a large job I did for some plaques and noticed that they "cupped" while in the shop, but when we brought them inside the AC and put some weight on them, they resumed the flatness in an acceptable manner. We then stained and sealed them and they look awesome.

My problem now is on a longer board / project. I have a 21'' long x 12'' wide board with a family name carved into it. The board cupped while sitting on my shop table so I brought it back inside my AC cooled house where it has been for 3 days now and it is not resuming its flatness. I need it flat or I am going to have to try and recarve the project which I dont want to do...

Any other suggestions how I can force the board to go back to flat??? I need a solution because the summers arent going to get any less warm / humid and I have a ton of orders coming in already.

Does Oak have the same tendency to cup or warp like this?

[FWMiller]

All wood expands and contracts with changes in moisture content. Oak is somewhere in the middle as there are woods that are much worse. The highest expansion is seen radially or perpendicular to the growth rings while it is the least in the direction of the grain. That's why certain cuts of wood have better behavior than others. The only way to minimize it is to reduce the variation in moisture content. Stabilize the wood to the closest moisture content that the end product will be stored in and then machine the wood to final dimensions. A final water resistant finish coat slows down moisture absorption and will lessen the effects of wood movement. If you check out a book called the encyclopedia of wood or others like it you will find much more info than you ever thought you wanted to know. A moisture meter is a good thing to have if you have lots of trouble and learning which boards to pick will save some of the headache.

[fwharris]

A good tip that was share here is to seal the ends of the board and any cut pieces being prepared for carving as soon as possible when you get them to your shop.