Acoustic Effect of Polyurethane Stain on Wood

[Ron Resnick]

Has anyone experimented with the acoustic effect of staining hardwood walls of a listening room with polyurethane stain or sealant?

Does polyurethane add sound reflectivity to the wood walls? Does polyurethane stain or sealant have any sonic effect at all versus not applying polyurethane to wood listening room walls?

 

[Steve Williams]

Has anyone experimented with the acoustic effect of staining hardwood walls of a listening room with polyurethane stain or sealant?

Does polyurethane add sound reflectivity to the wood walls? Does polyurethane stain or sealant have any sonic effect at all versus not applying polyurethane to wood listening room walls?

Ron

my best advice is to find out which lacquer van den Hul uses on his Stradivarius carts. That might be a game changer

 

[PeterA]

Ron

my best advice is to find is to find out which lacquer van den Hul uses on his Stradivarius carts. That might be a game changer

Hilarious, but I don't think Ron can afford that much quantity. Can you imagine the cost to finish his huge room?

Ron, I would be cautious about sealing the wood unless all six sides are sealed. The panels are already mounted to the wall, and presumably unsealed. Moisture could enter the back side and not escape if you seal the room side.

Have you considered simply oiling the wood? This would not seal it and allow it to breath. Was the previous grey stain on these panels a sealer or non sealing penetrating stain? I'd talk to a pro about this.

 

[Vienna]

Hi Ron, have a look here

https://www.researchgate.net/public...d_Acoustical_Properties_of_Wooden_Soundboards

 

[ddk]

Hilarious, but I don't think Ron can afford that much quantity. Can you imagine the cost to finish his huge room?

Ron, I would be cautious about sealing the wood unless all six sides are sealed. The panels are already mounted to the wall, and presumably unsealed. Moisture could enter the back side and not escape if you seal the room side.

Have you considered simply oiling the wood? This would not seal it and allow it to breath. Was the previous grey stain on these panels a sealer or non sealing penetrating stain? I'd talk to a pro about this.

I recommended Pure Tung Oil.

david

 

[PeterA]

I recommended Pure Tung Oil.

david

Some of the natural wood in our 200-year-old house as a tung oil finish. I’ve also used linseed oil. If you go this route, I don’t know if it will have to be reapplied after some time but the finish is usually a very deep rich look which would be nice in your room.

Polyurethane is like a plastic. I’ve never liked a plastic coating on natural wood. The exception is varnish on natural wood on boats because of the elements.

 

[ddk]

Some of the natural world in our 200-year-old house as a tung oil finish. I’ve also used linseed oil. If you go this route, I don’t know if it will have to be reapplied after some time but the finish is usually a very deep rich look which would be nice in your room.

Polyurethane is like a plastic. I’ve never liked a plastic coating on natural wood. The exception is varnish on natural wood on boats because of the elements.

I agree! Prefer pure Tung oil to linseed and you don't need to reapply for years and years.

david

 

[Mike Lavigne]

my 2 cents is you don't want a soft grained wood surface. you want a sealed cabinet surface that will be consistent. you want an engineered product of some sort. then you figure it out and it remains figured out. a stain is like shingles on a house. it ages and changes.

my whole room, walls and ceilings are finish grade 3/4" maple ply. damn heavy and screwed and glued. i have cloth over it where i need it for dealing with reflective glare, but other places i get the full energy. and now 16 years in it is still the same as new.

a soft grain stained wood will absorb and alter the tonality. and it will do it unpredictably. do you feel lucky?

and of course, if you are dealing with solid wood and not veneer you are going to have warping too. temperature change cycles will eventually do their dirty deeds.

as far as wood as art i agree.....stain has that soft finish. but you don't see a stained open grained wood on a guitar or violin or double bass. why?

 

[Ron Resnick]

Hilarious, but I don't think Ron can afford that much quantity. Can you imagine the cost to finish his huge room?

Ron, I would be cautious about sealing the wood unless all six sides are sealed. The panels are already mounted to the wall, and presumably unsealed. Moisture could enter the back side and not escape if you seal the room side.

Have you considered simply oiling the wood? This would not seal it and allow it to breath. Was the previous grey stain on these panels a sealer or non sealing penetrating stain? I'd talk to a pro about this.

The edges and back of the walnut panels were stained grey with the Rubio Monocoat Oil Plus 2C. So I think the other five sides of the planks have been sealed, or at least protected.

The coating I am considering now for the walnut panels at this point is a water-based coating which somehow looks invisible -- the wood ends up looking completely untreated.

 

[the sound of Tao]

Also just used pure Tung Oil on my last place for doors, interior walls and ceiling... adds a nice density and on interiors lasts many years.

 

[Ron Resnick]

Thank you for your assistance, gentlemen.

My concern with oils is that they darken or in some way change the natural appearance of the wood. The coating I am investigating is some kind of very light polyurethane, but it has no sheen or shine whatsoever, and somehow it leaves the wood looking completely untreated.

As long as there is no evidence that polyurethane changes the acoustic properties of the underlying walnut or changes sonic reflectivity, I think I am okay with this product.

 

[Ron Resnick]

Hi Ron, have a look here

https://www.researchgate.net/public...d_Acoustical_Properties_of_Wooden_Soundboards

Thank you, Vienna!

 

[Audiophile Bill]

Thank you for your assistance, gentlemen.

My concern with oils is that they darken or in some way change the natural appearance of the wood. The coating I am investigating is some kind of very light polyurethane, but it has no sheen or shine whatsoever, and somehow it leaves the wood looking completely untreated.

As long as there is no evidence that polyurethane changes the acoustic properties of the underlying walnut or changes sonic reflectivity, I think I am okay with this product.

Hi Ron,

I would personally avoid using a (plastic) poly finish on your walnut. Poly does affect the sound - I have tested various finishes over the last nearly 2 years and agree you are better with an oil or other natural finish. That being said, walnut isn’t known for its tonal properties per se so if it is more about the looks and you don’t want to darken the wood, then you might not have much choice.

One finish that doesn’t darken, is easy to apply, doesn’t crack, can be repaired, is hard wax oil - various brands available now. For the enormous surface area you are covering, I would use that myself. I would personally use the Osmo Polyx clear matte.

By the way - are you sure that the poly won’t crack as the wood moves? The plastic finishes do have a tendency to crack compared to other natural finishes and repairing it is a total mare.

 

[bonzo75]

Ron, irrespective of what you think of shun Mook vs still points, one would never paint over a shun Mook rack. It's criminal. Same with walnut

 

[the sound of Tao]

Hi Ron,

I would personally avoid using a (plastic) poly finish on your walnut. Poly does affect the sound - I have tested various finishes over the last nearly 2 years and agree you are better with an oil or other natural finish. That being said, walnut isn’t known for its tonal properties per se so if it is more about the looks and you don’t want to darken the wood, then you might not have much choice.

One finish that doesn’t darken, is easy to apply, doesn’t crack, can be repaired, is hard wax oil - various brands available now. For the enormous surface area you are covering, I would use that myself. I would personally use the Osmo Polyx clear matte.

By the way - are you sure that the poly won’t crack as the wood moves? The plastic finishes do have a tendency to crack compared to other natural finishes and repairing it is a total mare.

Wood moves with humidity... poly not so much. But that walnut does look lovely.

 

[the sound of Tao]

Ron, irrespective of what you think of shun Mook vs still points, one would never paint over a shun Mook rack. It's criminal. Same with walnut

Lol, how did Stillpoints v Shun mook work its way in here

 

[Ron Resnick]

The thin polyurethane I am considering apparently is designed to maintain elasticity to move with the wood.

I, personally, not knowing anything about wood or wood-working or wood finishing, thought that at least traditional polyurethane was kind of a hard and clear and coating/covering type of finish. Whatever this product is it literally looks like there is nothing on the wood. The porosity of the wood is still there; the wood doesn't look or feel sealed or "closed-up" or covered.

 

[bonzo75]

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Also just used pure Tung Oil on my last place for doors, interior walls and ceiling... adds a nice density and on interiors lasts many years.

Have you guys considered real wood to go with that

 

[Audiophile Bill]

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Have you guys considered real wood to go with that

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Ked the Altec 817 you posted is stained plywood not proper hardwood in the traditional sense. The Markus K horn in the other Altec mid horn looks like walnut.

 

[bonzo75]

Ked the Altec 817 you posted is stained plywood not proper hardwood in the traditional sense. The Markus K horn in the other Altec mid horn looks like walnut.

Yes it's Baltic birch