Need to pick a few brains about wood crack post project

Hey everyone, looking for a little help or ideas.

I’ve recently started making a few flags, first I made one for myself, then family for xmas. Now coworkers and family friends want to buy them! So I’m thinking awesome!

Well my first few flags I’ve recently saw cracks forming in the wood.

Each flag is made of “quality” (blue stripe) pine from Menards. I buy 1X8X6 boards and cut them down to 1.625" for the smaller flag or 2.75" stripes for the larger flags. After that I add Kreg pocket holes on the back sides. I then burn and stain them. Put them together with reg clamps to keep the boards tight and straight. Clear coat 2-3 times. Then of course bring them inside a house after. I live in Indiana. Lately its been darn cold here. Right now its below zero and my pole barn where I keep the wood is not insulated. When I do work in the barn i have a torpedo heater which gets it to mid 50s or so pretty quick.

Well anyone have ideas of why some of the boards are cracking… I mean the flags are really not that heavy I make two sizes. 22" x 41" (about 10 pounds) and 36" x 60 (not more then 20) " I brad nail 3 or 4 braces up the back side of each flag to give it more support. The union is its own piece of wood and that is plywood.

So I’d love to make these as I enjoy it. I use my X carve to do the stars and any personalized names or whatever on the long stripe below the union but I’m scared to sell them and then have customers flags crack!!!

I’m assuming its the weather “humidity” but I can’t control that. Has anyone else ever ran into this issue. I’m using quality pine as I stated also so its not the cheapest level which is standard (red stripe) pine. There is a higher level of pine but that is Select but that is 5 times the price and not even worth selling the flags then.

So far its only happened on the bigger 36" x 60 " (3x5) flags but just worries me I don’t wanna sell something that will look bad if it cracks!




I’ve attached a few photos. The other one that is crack is darn near have a length of a long stripe now…

Thanks everyone! Happy New Year and be safe!

Where are the cracks? Between the boards you’ve pocket holed together, or along the long grain of the boards? Are you using a jointer first?

Not using a jointer (wish i had one though haha) just my table saw to rip the boards down. The cracks are 100% going with the grain. The pic above shows a zoomed in shot of the small crack on the red stripe.

I just didn’t know if I should bring the boards inside my house for 2-3 days before putting them together to get them to the humidity and temp of a normal house. I know of course wood grows and shrinks with temps and humidity but I didn’t think it would be an issue to spilt a board right down the middle like that lol.

I know there is still a lot of learning for me to do , I’m young and just getting serious in wood working so any info is greatly appreciated.

i would say it is just the wood. are the flags for outdoor use or indoor use. i make all kinds of furniture from pine and what looks good today might not tomorrow. it could have a hairline crack and you can not see it. i am also from indiana and it is not just a little cold it is terribly cold.

Thanks Wayne Hall. They are for indoor use, but hell if someone wanted to put it outside they could. lol N yes it is brutal cold right now in Indy haha, don’t even wanna talk about wind chill right now haha

I just don’t want to sell one and have a person reach out to me and be like ur flag cracked. I want my money back or a new one. Idk what else I would say besides. its wood and it moves (best example i could give them is a wooden door. what closes easy now won’t in summer when the doors swell. ) haha Or say hey the crack adds a rustic look to the wood and burns grains haha

you never know what wood will do and you can move it in and make the flag and someone takes it home and has a higher moisure content in there house or drier anything can happen. you are about as close as anyone i have found with an xcarve. we need to talk some time. you are as local as i can find.

If there is any ambient moisture it will be drawn in from the end grain of your lumber. If your keeping it outside I would apply an end sealer to the ends of your boards, then just trim off each end to get rid of it when your ready to start your project. I would also bring the wood in a week or so before you begin working on your project. Flat sawn lumber is where you will see most of your movement and the cuts that are closest to the pith of the log is where you will see the least movement and cracking. Hope this helps.


Your problem is definitely humidity. You introduce a ton of humidity with the turbo heater, then when you bring them in the house it is very dry. Winter is always a hard time for woodworking when you don’t have a controlled environment. You might try to build them and then bring them in the house, wait a few days for them to equalize then finish them in the house.

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I let all my wood stabilize for at least a week. Just because the it is kiln dried doesn’t mean it is dry enough to work with. I operate a sawmill business and have had lumber dried in a vacuum kiln 8% minus for customers, then later they have complained that there wood is not dry because they stored it in a barn. I tell them think of end grain as a handful of straws and their lumber will rehydrate to the moisture level of the room it’s stored in.


I know most won’t or can’t do this, but I usually let wood relax/stabilize in my shop for a few months before I cut it. Pine from the bigbox stores (just like @RobertCanning said is usually high in moisture and needs to dry out a bit before using).


I would bet money it’s at the least 10-12%. I live on an island that is mostly rain forest and it doesn’t take long for wood to be rehydrated… just my 2 cents.

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It’s in all of our species of Pine except for Jeffery Pine for the most part.

It looks like your stars are on plywood (generally very stable) and your stripes are on pine. I noticed you used pocket holes to attach the the stripes to the star plywood. The stripes will expand and contract along their width based on humidity levels but the pocket screws into the stable plywood (that doesn’t expand-contract) prevent the expansion-contraction causing the crack.

At least that is my guess.

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Everyone’s got great points here. To make the best try with the wood you have try these practices to reduce the wood movement. (definitely acclimate the wood a few days before you use it)

  1. Finish BOTH sides of the piece the same, at a minimum Prime the back and sides with either a sanding sealer or kilz
  2. Change the way you join the boards with pocket screws to maybe a tongue and groove set up. you can cut these on your table saw.
  3. Use glue instead of screws, and use glue that has some elasticity like titebond 3.
  4. Another option might be to just use plywood for the strips instead of pine, as it is much more stable and will have no movement.

Best of luck, these look really fantastic !

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I have a garden bench project I started in August every time I start working on it there’s some storm that I have to go adjusting. That oak is good and cured. Maybe I can get it done this winter? Not likely coldest winter in Kansas for a long time lots of frozen pipe claims already.

There’s a lot of good advice here. I’ve sold quite a bit of lumber in the last few years and was very new going into the business. One thing I quickly learned is that wood is like a sponge. Wood will absorb and lose moisture to remain in equilibrium with the moisture in the air. I’ve had lumber that was kiln dried to 6-8% moisture content go upwards of 14% when stored in a humid environment. Here is some info on the subject.

Like others have said if the flags are intended for indoor use I’d bring them inside for a little while to acclimate to a drier climate. Although this can vary based on your location and other factors. Right now in my home the humidity is only about 25% so it would keep wood at a low moisture content. Also sealing the wood very well is key, especially the end grain.

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Thanks Robert if your ever out this way, your always welcome to stop by.

Pretty much agree with everything Robert said and Peterfroh said.

I build acoustic guitars and RH is extremely important with the thin woods being used

The members here have given some excellent advice.

The wood needs to be acclimated well to the environment and needs to be relatively dry to begin with. What the big box stores sell does not necessarily meet this criteria. They make their money by selling in bulk and getting it out the door as soon as they can. So most of what you purchase will not be fully dried. Even the Kiln dried wood. Keep in mind this lumber is not always locally sourced and is shipped 100’s if not 1000s of miles from where it was harvested. This means it’s constantly taking on and letting out moisture. There is no guarantee that the wood did not get rained on either.

With all that said. It’s best to allow your wood to acclimate to your local environment first, sorry to say this could take months or even years depending on multiple factors. Stack it and sticker it along it’s len to allow airflow on all 6 sides and it doesn’t hurt to add extra weight to the stack while it dries to help keep the stock flat. Of course quarter sawn lumber will be the most stable dimensionally.

Once the wood has acclimated to the environment, then it needs to acclimate to the environment it will “live” in. For instance, Being stored in a barn, then machined, then moved indoors (especially in winter) can really wreak havoc on the work piece.

This is why I have to maintain a RH level in my shop between 42-47% year round. If the final piece is being sent to a region with lower RH, such as a desert, I have to lower my shop RH even more.

Wood continues to shrink as it looses moisture, and this process “can” go on for years until it reaches equilibrium. Thin woods tend to reach equilibrium sooner than thicker woods. Once the wood shrinks, it rarely ever rebounds to its original size even if the moisture content is the same. This is why it’s best to fully dry the wood first. Then Mill the wood to close to your final dimensions, let it sit overnight or a few days and then Mill it to final dimensions. If you watch Rough Cut with Tommy Mac, you will see him use this process. Also speak to some wood turners. They will turn their wet blanks to rough shape and slowly dry them over a period of weeks/months before they do their final shapes. (Some of this is due to them using green wood) Even after the wood has been dried it can continue to change shape for a multitude of reasons. Even the heat induced during milling/shaping can cause the wood to change shape.

And people wonder why wood working is an ART Form!!!

Wood can be extremely finicky when it comes to moisture.

Get yourself a good moisture meter and a proper area to allow your wood to dry. Next pay attention to the atmosphere while you are working. Just because you are in your shop and it’s dry does not mean it is a good time to mill lumber if it’s raining outside. The RH of your shop can make a Significant Difference.

To get around these pitfalls you can use multiple techniques such as using plywood, or using different joining techniques such as ship-lap.

The wood will technically never stop moving, you just need to understand how it will move and where it will move and compensate for this because the wood will do what it does.

Sealing the end-grain will help once the wood is dried and if you finish one side also finish the other side. This way one side does not absorb more moisture.

You also need to pay attention to how the grain runs in the wood and how it runs in the pieces attached to it.

Woodworking is an Artform. So it is best to learn as much about the medium you are using to construct this art.

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