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post #1 of 18 (permalink) Old 05-23-2014, 01:15 PM Thread Starter
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Default Question: Finishing Rules

Over the last 35 years I have heard this said many times: "You need to seal the wood inside and out." Then the next guy comes along and tells me; " You should NEVER seal both sides of the wood, as it needs to breath."
I would really love to hear the official ruling on this subject from someone who knows exactly why and when these rules apply.
I am in the process of building a "Highboy Chest of Drawers" with Red Oak. It will have a lighter stain and a poly finish. I am attempting to make a family "heirloom piece". I really want to do this the right way.

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post #2 of 18 (permalink) Old 05-23-2014, 04:40 PM
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Reg; I can't speak to 'Rules', but all our antique furniture is unfinished on the unseen surfaces, all of the older but not quite antique, same thing.
Don't know if that helps; I'm talking about beginning of the 20th century to maybe the '40s.
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post #3 of 18 (permalink) Old 05-23-2014, 05:48 PM Thread Starter
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Thanks Dan. I am leaning towards leaving the inside not coated. Much less work.

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post #4 of 18 (permalink) Old 05-23-2014, 06:19 PM
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I am not a finishing expert but my understanding is that veneers, ply and other laminates must be finished both sides to control moisture content. Solids do not need to be finished both sides. For example solid wood drawers are never finished on the inside because of the lingering odour of the finish. No harm done by not finishing these both sides. I have never had a problem arise by not finishing both sides of a solid case.
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post #5 of 18 (permalink) Old 05-24-2014, 08:12 AM
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Hi Reg, I didn't know wood breath. That's news to me. I have been building furniture for 40 years and I always finish both side of the wood the same - whether it is a table, desk, drawers, etc. That is to prevent one side from taking in more moisture than the other. For boxes, drawers, and areas that will be closed, I never use an oil finish on the inside because of the lingering odor. I generally would finish those with either shellac or polyurethane and again I would do all sides with it. Hope this helps. Malcolm / Kentucky USA
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post #6 of 18 (permalink) Old 05-24-2014, 10:41 AM
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Malcolm you are correct, all this 'wood has to breath' stuff is wrong, To make any piece of furniture then you need to work with wood with the correct moisture content and that is normally around 10%, it varies a little, anyone who has a set of drawers where they get stuck and won't open will know that wood expands when its moisture content rises, so doors get tighter and drawers won't open, so once you start with wood that has the correct moisture content then to keep it that way it has to be sealed up and then the moisture content will stay the same regardless of the ambient air. many manufacturers say this 'wood has to breath' stuff, they say it as a plausible reason as to 'why' they did not take the time and spend the money to polish the item all over. When the moisture content is allowed to wander around then this movement is the reason why wood cracks as it gets older, it is true that if an item is not polished all over and it is then kept inside and in an area where the ambient moisture does not wander around that much, then this item will not get attacked the way it would be if it were moved from and area of the land where the moisture content is static to one where is does go up and down, so this item could be used as an example of how an item that was not sealed up then survived many years and like Reg says, 'it is much less work' however this 'let the wood breath' to put it 'bluntly' its crap, wood that is allowed to breath will get attacked by moisture and mover around and crack, it won't happen over night but it will happen. Neville
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post #7 of 18 (permalink) Old 05-24-2014, 11:35 AM
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Reg,

I will tell you and all the definitive correct answer - and I can let each one of the naysayers "prove" this to each of themselves!.. Malcolm and Neville hit the perfect answer. Read both of those - they are both dead-on!

Now, you may be wondering how you can see this for yourselves! Quite simple actually - cut a scrap of wood - relatively thin and it doesn't need to be much over 12" x 12" (30cm x 30cm for you guys that use GOD'S SYSTEM). Lay it in your yard - preferably over a lawn area. In a few days - check-out the flatness of the board compared to what it was when it was laid in your yard. ESPECIALLY during the summer months, if the underside is moist and the upperside is getting sun-dried, you can be sure it will curl-up! The reason is simple: different moisture content from the two sides.

Molly is our (almost 13) getting old Boston Terrier. When she's asleep and NOT SNORING - we carefully look to see if she is breathing. If she is breathing - it is a sign of life. When she stops breathing, she will be dead - like your wood - dead things don't "breathe". There's a huge difference between absorbing moisture and breathing!

Joy's Dad made high-quality furniture for 54+ years. I learned a lot from him. Whenever we would go places, he would pull-out drawers or open cabinets or look at undersides of tabletops. It was to be expected from him. He wasn't just an extremely gifted wood-worker, he was extremely knowledgeable about anything to do with wood! His reason for looking at those parts of furniture that "typically doesn't show" was simple - he had a name for furniture where the interior (hidden) surfaces were unSEALed: JUNK!

Otis Guillebeau from Auburn, Georgia (age 60, keenly observant for 57 of those years)

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Last edited by OPG3; 05-24-2014 at 11:37 AM. Reason: left out a word
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post #8 of 18 (permalink) Old 05-24-2014, 04:02 PM
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See Reg? Lots of opinions to choose from. The 'seal everything' guys are probably correct in that it a better approach, but neither the norm nor mandatory.
Having said that, if you were spray finishing, why not hit all the surfaces?
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post #9 of 18 (permalink) Old 05-24-2014, 06:17 PM
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Quote:
Originally Posted by OPG3 View Post
Reg,

I will tell you and all the definitive correct answer - and I can let each one of the naysayers "prove" this to each of themselves!.. Malcolm and Neville hit the perfect answer. Read both of those - they are both dead-on!

Now, you may be wondering how you can see this for yourselves! Quite simple actually - cut a scrap of wood - relatively thin and it doesn't need to be much over 12" x 12" (30cm x 30cm for you guys that use GOD'S SYSTEM). Lay it in your yard - preferably over a lawn area. In a few days - check-out the flatness of the board compared to what it was when it was laid in your yard. ESPECIALLY during the summer months, if the underside is moist and the upperside is getting sun-dried, you can be sure it will curl-up! The reason is simple: different moisture content from the two sides.

Molly is our (almost 13) getting old Boston Terrier. When she's asleep and NOT SNORING - we carefully look to see if she is breathing. If she is breathing - it is a sign of life. When she stops breathing, she will be dead - like your wood - dead things don't "breathe". There's a huge difference between absorbing moisture and breathing!

Joy's Dad made high-quality furniture for 54+ years. I learned a lot from him. Whenever we would go places, he would pull-out drawers or open cabinets or look at undersides of tabletops. It was to be expected from him. He wasn't just an extremely gifted wood-worker, he was extremely knowledgeable about anything to do with wood! His reason for looking at those parts of furniture that "typically doesn't show" was simple - he had a name for furniture where the interior (hidden) surfaces were unSEALed: JUNK!

Otis Guillebeau from Auburn, Georgia (age 60, keenly observant for 57 of those years)
Otis, your example is extreme and not really relevant to furniture in a controlled environment.
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post #10 of 18 (permalink) Old 05-24-2014, 06:24 PM
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Quote:
Originally Posted by neville9999 View Post
Malcolm you are correct, all this 'wood has to breath' stuff is wrong, To make any piece of furniture then you need to work with wood with the correct moisture content and that is normally around 10%, it varies a little, anyone who has a set of drawers where they get stuck and won't open will know that wood expands when its moisture content rises, so doors get tighter and drawers won't open, so once you start with wood that has the correct moisture content then to keep it that way it has to be sealed up and then the moisture content will stay the same regardless of the ambient air. many manufacturers say this 'wood has to breath' stuff, they say it as a plausible reason as to 'why' they did not take the time and spend the money to polish the item all over. When the moisture content is allowed to wander around then this movement is the reason why wood cracks as it gets older, it is true that if an item is not polished all over and it is then kept inside and in an area where the ambient moisture does not wander around that much, then this item will not get attacked the way it would be if it were moved from and area of the land where the moisture content is static to one where is does go up and down, so this item could be used as an example of how an item that was not sealed up then survived many years and like Reg says, 'it is much less work' however this 'let the wood breath' to put it 'bluntly' its crap, wood that is allowed to breath will get attacked by moisture and mover around and crack, it won't happen over night but it will happen. Neville
A drawer or door that sticks when the humidity rises has been made incorrectly. Yes, wood will expand as moisture in the air increases, but this has to be taken into consideration in making the piece. It is highly unusual to see a piece of furniture finished the same on the interior as the exterior. Some people use shellac on the inside and this is fine. But unless the inside and outside are finished the same there will be different stresses on the piece.
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