How to "uncup" my new wood

[OCtoolguy]

I ordered some red oak and some maple in 1/4" thickness. The red oak is 6" wide by 48" long. The maple is 1/4" thick by 8" wide by 48" long. I unwrapped it a few days ago and let it sit upright in my workshop. Now, I have some very nice cupped wood. It's only cupped about 1/16" but I need it to be flat. I did cut it all into 10" lengths for my project. Have any of you ever had success with wetting the wood on the cupped side and clamping it face down to a flat surface? I know I saw something on one of Steve Good's blogs but I was just wondering if any of you have done it. I'm hoping that I can do more than one piece at a time by alternating them in stacks of 4. 

 

[JTTHECLOCKMAN]

This question came up not long ago and the consensus was yes on the wetting. but I will tell you from woodworking for a long time you will not eliminate it. The tree it was cut from may have had stress points in its growth cycle and there is not much you can do. Hopefully after you get flat and scroll it, the fret holes will release some tension. But a more stable backing maybe needed when done.  

[Sycamore67]

Thin wide wood will cup.  If it is  quarter sawn, it will cup less.  You can try things to flatten it but not very successfully.

[Roberta Moreton]

I have done it. I don’t clamp it. I get it wet, not soaked. Sometimes I will set it outside and let the NC heat and humidity work. I put something on it. I don’t want it to break, so nothing super heavy, just pressure. 

[redwine]

I have used the method that Steve put out on his site not long ago and it does work to a small amount. As stated you cannot get the wood completely flat but within 1/32" which is useable. Now having said that, I had ordered 1/4" maple 1/4" x 24" X 8" and it started to cup a couple of days later. I decided to try the process and I wasn't expecting what happened. I wish now that I had taken a photo of the result! I had done the  wetting and put the stickers down than placed the wood with two weights on the stickers and left it alone. That afternoon I went to check on the process and the wood had done a cupping that was an arch! Now these weights weigh about 15# and that maple had pushed them up a good 3inchs! I was eventually able to get the wood flatten somewhat but ended up  cutting it into 4inch wide strips and used it for ornaments. Every day I find out more about what wood will and won't do!

Erv

[JTTHECLOCKMAN]

Erv so true man. Mother nature made that material and it has a mind of its own. That is why in furniture building you have to compensate for wood movement at all times. No different in what we do too. When doing fret work you do release some of the internal stress though so that helps some.

[JAC1961]

I've made some signs that I first heavy burn the main background board and then wire wheel off the burnt material (known as shou sugi ban).  This sometimes creates some major cupping.  Since it's supposed to be a rustic appearance, sometimes I can live with it, but if I'm going to CNC afterwards it has to be somewhat flat.

I've had fairly good luck with putting a well wet towel on the concave side and going over it with an iron... my iron that I bought and keep in the shop for just such tasks lol.  I leave it in one place for a good length of time, probably at least 30 seconds before moving it.  I do the entire area and then re-wet the towel and do it again.  I then flip it over, put a couple jointed 2x4's perpendicular to the cup and add some good heavy stuff.  If it's dry I throw the wet towel over everything so slow drying.  It usually flattens well, but it's a crap shoot whether it stays or not.

[JLawson56]

A lot of Great Info here.I buy 4x8 sheets of 1/4 luon when mine starts to bow or cup I turn them over and put some weight on them..Takes care of the problem.I like the damp Idea.

[OCtoolguy]

19 hours ago, JAC1961 said:

I've made some signs that I first heavy burn the main background board and then wire wheel off the burnt material (known as shou sugi ban).  This sometimes creates some major cupping.  Since it's supposed to be a rustic appearance, sometimes I can live with it, but if I'm going to CNC afterwards it has to be somewhat flat.

I've had fairly good luck with putting a well wet towel on the concave side and going over it with an iron... my iron that I bought and keep in the shop for just such tasks lol.  I leave it in one place for a good length of time, probably at least 30 seconds before moving it.  I do the entire area and then re-wet the towel and do it again.  I then flip it over, put a couple jointed 2x4's perpendicular to the cup and add some good heavy stuff.  If it's dry I throw the wet towel over everything so slow drying.  It usually flattens well, but it's a crap shoot whether it stays or not.

Thanks for the info. I'm glad you added the part about having your own iron. I can't imagine the Hell I'd have to pay if I took my wife's favorite tool out to my shop.

 

[SCROLLSAW703]

Howdy, 

I second the wet towel and iron deal. I picked up an iron at the local thrift store a year or so back, and used it on some oak I had for a tractor project. The oak was a 1/2'' thick x 12'' x 12''. I done the same thing with the wet towel several times and used medium heat on the iron. I had excellent results! I was able to finish plane it and run it thru the drum sander, and wound up with perfectly flat faces on the oak.

I have also used it on picture frames that customers have brought into the shop that were old enough to belong to another generation, and have warped some. I use a bath towel soaked to start, and wrap the towel around the entire frame till the towel dries, then wet it again, and start in one corner of the picture frame with the wet towel and the iron, and work around the frame til I get all the way around the frame. I can get the frame straightened out enough to put glass and the picture back in it. And refinish it, if that is their instructions.

Sawdust703(Brad)

[OCtoolguy]

26 minutes ago, SCROLLSAW703 said:

Howdy, 

I second the wet towel and iron deal. I picked up an iron at the local thrift store a year or so back, and used it on some oak I had for a tractor project. The oak was a 1/2'' thick x 12'' x 12''. I done the same thing with the wet towel several times and used medium heat on the iron. I had excellent results! I was able to finish plane it and run it thru the drum sander, and wound up with perfectly flat faces on the oak.

I have also used it on picture frames that customers have brought into the shop that were old enough to belong to another generation, and have warped some. I use a bath towel soaked to start, and wrap the towel around the entire frame till the towel dries, then wet it again, and start in one corner of the picture frame with the wet towel and the iron, and work around the frame til I get all the way around the frame. I can get the frame straightened out enough to put glass and the picture back in it. And refinish it, if that is their instructions.

Sawdust703(Brad)

That's amazing Brad. I sure do wish I had a drum sander. Actually, I wish I had room for a drum sander.

 

[OCtoolguy]

@SCROLLSAW703I'm going to hit the local Goodwill stores to see if I can find an old iron. I like that idea. How wet do you get the wood before "steaming" it?

 

[SCROLLSAW703]

Howdy Mr. Ray, 

Thank you, Sir. I had tried everything else I could dream up to "straighten" that given piece of wood, Mr. Ray. I finally came up with the brilliant idea of using the iron and the moisture to try to de stress the pressure points that were cupped. Little by little, lt began to level out and look presentable. Once I got it to the point of nearly completely flat, like I said before, I ran it thru the planer a couple times to clean it up, then thru the drum sander with 150 grit, and when I checked it with a square, I had a completely flat, square piece. 

It was a time consuming process, but as pricey as oak is on this side of the rock, a feller has to figure out how to make use of every inch possible. And my drum sander ain't a monster drum sander, Mr. Ray. It's a 10'' sander. It sits on a tool stand in the corner of the shop by the grinder til I need it. I pull it away from the wall a ways, and use it, then push it back in its corner. 

Sawdust703(Brad)

[SCROLLSAW703]

Howdy Mr. Ray,

The way I go about it, I use a spray bottle and spray the wood with water, then put a wet towel over the wood to prevent the iron from burning the wood, and allow it sit there and steam the moisture into the wood to allow the stress points to relax, Ray. I wouldn't drench the wood, Sir. You're just asking for more trouble if you go about it that way. 

Call me if I can be of help, Sir.

Sawdust70s(Brad)

[OCtoolguy]

1 minute ago, SCROLLSAW703 said:

Howdy Mr. Ray,

The way I go about it, I use a spray bottle and spray the wood with water, then put a wet towel over the wood to prevent the iron from burning the wood, and allow it sit there and steam the moisture into the wood to allow the stress points to relax, Ray. I wouldn't drench the wood, Sir. You're just asking for more trouble if you go about it that way. 

Call me if I can be of help, Sir.

Sawdust70s(Brad)

I was taught in high school wood shop class that you can take a dent out of wood the same way. I am going to give this a try. A couple more questions..... how much cup were you able to cure? And what brand/make of drum sander do you have. I might start looking for a used one. I know I'm probably dreaming but who knows?

 

[SCROLLSAW703]

Hello Ray,

When I started working on the piece, it had exactly an 1/8'' cup in it. That was the reason I wrapped in the big bath towel completely soaked first before I even started with the iron. That gave the wood a chance to absorb the moisture from the towel until the towel dried.

Then when I started in with the iron, I dampened the towel, laid it on the beginning of the upside of the cup, and laid the iron on the towel and let it dry the towel in that spot, and just kept working along the edge of the cup, and flattening the cup. 

Like I said, it was a time consuming process Mr. Ray, but it worked with outstanding results! 

Sawdust703(Brad)

[OCtoolguy]

5 minutes ago, SCROLLSAW703 said:

Hello Ray,

When I started working on the piece, it had exactly an 1/8'' cup in it. That was the reason I wrapped in the big bath towel completely soaked first before I even started with the iron. That gave the wood a chance to absorb the moisture from the towel until the towel dried.

Then when I started in with the iron, I dampened the towel, laid it on the beginning of the upside of the cup, and laid the iron on the towel and let it dry the towel in that spot, and just kept working along the edge of the cup, and flattening the cup. 

Like I said, it was a time consuming process Mr. Ray, but it worked with outstanding results! 

Sawdust703(Brad)

How large a piece are you talking about Brad? I'm trying to envision your description. 

 

[SCROLLSAW703]

Hello Ray, 

The piece I started out with was 12'' x 12'' square. By the time  I had it flattened out and cut to size, the actual project piece was 9'' x 10''. The thickness of the wood was right at a half inch thick. It took damned near a full day to get that piece completely flattened out, but I finally got it done.

Brad.

[OCtoolguy]

Wow! That's pretty thick. I'm only talking about 1/4" stuff. That should be fairly easy to "uncup". The folks who I bought my wood from got the order messed up and sent me 1/4" oak but they sent 1/8" maple so they corrected that. I ended up with a free piece of maple but it is cupping now too. I don't have space to "sticker" it so I guess I'll have to do the whole process on it too.

 

[SCROLLSAW703]

Hello Mr. Ray, 

To be honest, with the width and length you have to take into consideration, were I you, I would lay it flat on the concrete floor in your shop for the time being, and get some sort of weight down thru the length of the material until you are ready to work it. The more weight the better, but be cautious to distribute the weight equally the full length and width of the material. With the humidity, the flattening process will begin as the wood takes on moisture and the stress points begin to release with the pressure of the constant weight on it. 

Sawdust703(Brad)

[scrollntole]

I followed Steve Good directions twice w/o luck. Same Red oak and thickness. Yet I've been OK if I take wood out of plastic wrapping and immediately start to cut. This keeps the warping to a minimum for me. That's my experience so far.

Vin

[JAC1961]

On 11/24/2018 at 3:44 PM, octoolguy said:

I'm going to hit the local Goodwill stores to see if I can find an old iron.

 

If you can't find a used one, I got mine at one of the dollar stores for $10 and it's worked well.

[OCtoolguy]

20 minutes ago, JAC1961 said:

If you can't find a used one, I got mine at one of the dollar stores for $10 and it's worked well.

I keep forgetting about the dollar stores. Thanks. I'll check it out.