WOOD SHRINKAGE!

[AON]

Well that got your attention!

 

I have a hard maple wooden frame 24" x 30" with four corner tongue and groove joints.

They were glued with yellow PVA carpenters wood glue.

I had to take them apart so I wrapped the corners in cloth, soaked the cloth with 91% Isopropyl (rubbing) alcohol and wrapped that in plastic wrap so the alcohol would not evaporate.

Left it overnight.

Next morning each joint came apart easily.

Cleaned the joints of residual glue and dry fitted them back together.

The tongues are 3/16"shorter when they were originally flush to the outside of the grooves.

 

This logically seems like shrinkage... due to the Isopropyl alcohol(?)

I have not experienced this before in model building as the parts are so small (not 24" x 30") so I guess it was simply not noticeable.

I soaked the tongues in water and left them 24 hours.

Now they are each about 1/8" short.

 

Has anybody experienced this before?

How long will it take to recover?

Will it recover?

 

 

[bruce d]

I have encountered this a few times when trying to repair/restore picture frames. Never found any rhyme or reason, even found one frame where two pieces shrank and the other two didn't. 

No solution but.... you are not alone. I will be interested if anyone can shed light on this. 

[druxey]

With only 9% water in your isopropanol, the wood should not have changed dimension by much at all. If anything, water should have expanded the wood, not shrunk it! As you know, wood changes dimension far more across, not along the grain. So what you describe is illogical. My only thought is that the wood was not seasoned when originally put together, but the glue joints were strong enough to constrain the wood. Unlikely, of course, but what other explanation can anyone offer?

[Ian_Grant]

Could Mrs. AON be pranking you? 😀

[AON]

Yes Druxey.

So it is like in religion ... t'is a mystery?

Hence I ask the masses here as I hope for a light to help understand and hope for a full recovery so I can reassemble the original pieces properly.

[AON]

Don't be talking about the Mrs and my wood.  😲

[hollowneck]

This involves the water and math calculations of Archimedean physics: soak the tongues for another 24 hours and you'll possibly be close to their original configuration.

If not successful, toss the whole lot and start over!😂

[OllieS]

2 hours ago, druxey said:

With only 9% water in your isopropanol, the wood should not have changed dimension by much at all. If anything, water should have expanded the wood, not shrunk it! As you know, wood changes dimension far more across, not along the grain.

This is the explanation surely: the grooves expand more than the tongues because they are at right angles grainwise, so you just need to leave it to dry out maybe.

[jud]

I would assume that the isopropanol dried the end sections of your frame and the wood was not acclimated to the moisture in the space you are working. Now you have a structure who's members are internally stressed and the moisture content is not uniform throughout and it will be changing shape and dimensions until all are uniform. Throw it all into a bath of isopropanol for 48 hours and then remove it and let it dry and stabilize a couple of weeks undisturbed in a airy space. Your joints will still not fit and all of the dimensions will have changed, start over with different stock.

 

Edited October 30, 2022 by jud

[druxey]

Aren't we all so helpful?

[AON]

The wood has been in my basement for about 10 years so it is aclimated.

 

I won't throw it out because it is good wood... just not for this project.

 

I will do it over.

[AON]

Actually yes y'all are.

I'm not crazy.

But what ever I am, I'm in the best of company!

[garyshipwright]

😊🥰

[Oldsalt1950]

You have just discovered the hydroscopic properties of wood. The Isopropyl removed what moisture it could from the wood = shrinkage. Water bath, rehydrated = swelling. The wood needs more moisture. Think of it like a boat, out of water the hull dries out a bit and some seams will if not properly calked open up. Put the boat back in the water and the seams leak until they swell up. If not enough water can be absorbed by the wood, you keep bailing the boat out. Thus, ends today's physical science lecture this information is testable!!!!