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Forum HostPermalink Reply by Lewis Kauffman on February 21, 2012 at 7:22am

Great explanation, Cliff, Thanks!!

Cliff R said:

The advantage is you get a shiny surface.

They are sort of similar between wood and metal  What happens in wood is not at all what happens in metal and  I believe that the the word is a metal working term that may not be appropriate to wood.  Wiki has a pretty good working definition.

In terms of look and feel burnishing  might  seem pretty much the same whether it's metal work or wood work.  The superficial  effect that things come off with a polished look.  In steel and copper based metals Burnishing usually affects the first couple of thousandths of metal, work hardening it as well as aligning the crystalline  grain structure and  closes up surface scratches  by rolling them into each other.

In all metals, whether they can be work hardened or not,  burnishing is not a stock removal process but a material reforming process. 

 

In wood  I believe much of  what is going on is  abrasive.  But there may be more.

Abrasion is  less complicated than burnishing. But it makes for a shinier surface & closes up surface scratches.  .   

 I am unsure whether the word  burnishing is the best word to use  for the act of of substituting saw shavings for sand paper in woodworking, because of the stark disparities between what  is actually happening in the material when one burnishes metal as  opposed to  wood.

But people like the word.    I think polishing might be the better word. It might also be insufficient.

 Rubbing saw shavings on a wood surface at high speed on a lathe produces heat  (if one rubs hard that is).   Sufficient highly localized Heat may loosen the lignin bonds in the wood fibers near the surface allowing them to be  bent over in one direction and then when the lignin  re-establishes itself to remain there permanently thus  giving the surface a sheen that might refract light  in a unique way. 

 

A very different process from metal burnishing but something much more than polishing

---

Lew-
Time traveler. Purveyor of the world's finest custom rolling pins!

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Master CarpenterPermalink Reply by SQ on February 21, 2012 at 4:39pm

Cliff,

Agree with Lewis, excellent explanation.  Thanks for the information.

SQ
Cliff R said:

The advantage is you get a shiny surface.

They are sort of similar between wood and metal  What happens in wood is not at all what happens in metal and  I believe that the the word is a metal working term that may not be appropriate to wood.  Wiki has a pretty good working definition.

In terms of look and feel burnishing  might  seem pretty much the same whether it's metal work or wood work.  The superficial  effect that things come off with a polished look.  In steel and copper based metals Burnishing usually affects the first couple of thousandths of metal, work hardening it as well as aligning the crystalline  grain structure and  closes up surface scratches  by rolling them into each other.

In all metals, whether they can be work hardened or not,  burnishing is not a stock removal process but a material reforming process. 

 

In wood  I believe much of  what is going on is  abrasive.  But there may be more.

Abrasion is  less complicated than burnishing. But it makes for a shinier surface & closes up surface scratches.  .   

 I am unsure whether the word  burnishing is the best word to use  for the act of of substituting saw shavings for sand paper in woodworking, because of the stark disparities between what  is actually happening in the material when one burnishes metal as  opposed to  wood.

But people like the word.    I think polishing might be the better word. It might also be insufficient.

 Rubbing saw shavings on a wood surface at high speed on a lathe produces heat  (if one rubs hard that is).   Sufficient highly localized Heat may loosen the lignin bonds in the wood fibers near the surface allowing them to be  bent over in one direction and then when the lignin  re-establishes itself to remain there permanently thus  giving the surface a sheen that might refract light  in a unique way. 

 

A very different process from metal burnishing but something much more than polishing

---

Happiness is wood chips flying!

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Master CarpenterPermalink Reply by steven newman on February 22, 2012 at 5:17am

  When I turn spindles, i will grab a piece of matching hardwood( like Oak) and burnish the spindle smooth with it.     I like the idea of a long stick i can control, more than a handful of shavings i'm pressing against a spinning piece of wood with my bare hands.    The shopsmith demo one year at the Ohio State Fair showed how to do it.    They also showed a way to darken a piece by hold the burnisher a bit too long in just the right places.  

---

'and may the road raise up to meet ye'

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CarpenterPermalink Reply by Arlin Eastman on February 22, 2012 at 1:51pm

Sue

There is one thing about burnishing that has not been brought up.  When you burnish you close off the cells or crush the wood into the cells.  If you are wanting to put a penatration sealer or finish into it, it will not work since eveything is now closed.

Hope it helps

Arlin

 

PS - I have been working on a metal burnihser for turning before I went into the hospital.  I will let you and everyone else know more when it is done.

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