What is burnishing?

[Rosanne]

HI all, I frequently see the term burnishing used regarding finishing. What exactly is it, how and when is it used? Thanks. -Rosanne

[knothead]

Hard woods are best to use with this. Rub them along one another, the more important one should be rubbed down its grain, but crossways will still work, and shortly a glossy sheen will come up and the wood will become slick. Burnishing does not protect the wood like a varnish does, but you do not have to wait for a burnished piece of wood to dry as you would if you had varnished it.

Tom

[GrayBeard Phil]

What Tom said....

However, to be more generic...Per WIKIpedia, the online encyclopedia burnishing comes from other crafts, pottery, silversmiths, goldsmiths, and so forth. A surface, like gold or unfired pottery, is rubbed with a piece of bone, very hard wood, or soft stone. It is my understanding that with gold leaf applied over base material (bronze? wood?), a process called gilding, the burnishing does something to the surface of the gold to make the thin surface of the gold metal 'flow' over the joints of the gold leaf to make the joins invisible.

Carvers, I think, will use burnishing more often than other woodworkers. When I did more main stream woodworking (furniture making) burnished wood was a very undesirable effect; it was to be avoided at all costs.

Burnishing wood will slightly alter the wood surface. The surface of wood is made up of dried and collapsed cell walls from the living tree. (a normal living tree cell is mostly water, which is removed in drying of lumber.) As you burnish, the softer material of the cell walls will rub off, leaving the harder cellulose fibre structure. This cellulose structure is further compressed and joined to other cell wall similarly compressed and altered.

The overall effect is to create a hard cellulose barrier against any dye, or finish absorption by the surface of the wood. That is why experts claim when you sand raw wood beyond 320 grit sandpaper, you are not sanding and are burnishing the wood. Some people like that finish effect and use it to their advantage.

Others claim you apply a couple of light coats of finish, then sand with 400 grit and progressively up to 1000 grit to the thin layers of finish, which flattens and burnishes the finish (not the wood) and this has a different look to the finish. The burnished finish look is very desirable to mainstream woodworkers. Most mainstream woodworkers become totally shocked when someone mentions they sand raw wood beyond 320 grit; it is that ingrained into the psychic of the mainstream woodworker.

The claim is that burnished finish gives the wood a depth of shine; like a mirror. Burnished raw wood with a clear acrylic finish, (glaze, polycrylic, many water-borne finishes) just sits on top of the wood and acts like a clear protective coating like an automotive clear coat; a different finishing effect. Again, burnished wood is used by some for effect.

French polish with shellac is a form of burnishing the finish on very expensive furniture, IMHO.

I did read somewhere that the act of burnishing creates mini-areas of local heat as you burnish. That is how the cellulose fibres get joined. I cannot comment on that. But the word 'burn' is in there and been there for a long, long time.


I hope what I said is helpful to understand burnishing.

Phil

PS: thank you for an excuse to procrastinate doing some household chores.

[workin for wood]

Burnishing is when you try and catch a fish using a Bic lighter as bait.

[jigsue]

Phew Phil

That explains it perfectly!

Sue

[Forester21]

Phil - thank you for that explanation!! Not that Tom's was bad, but your explanation went to more depths. Now I am beginning to understand why you would sand between finishes with such fine sandpaper.
Theresa

[JimSawyer]

Very informative Phil. I'll never look at finishing the same way again!
Jeff, That was a total mis-use of electrons, ow, lol.

[knothead]

Phil,
You have got to cut back on the caffeine.

Tom

[lucky788scroller]

No Phil DONT cut back on caffeine, I learn tons from you! dale

[Tor]

I too enjoy your wordy posts, Phil, so for me, go ahead and continue.

Tor