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Discussion in 'Finely Finished' started by otterhound, Apr 24, 2012.
For anyone interested , there is a good tutorial at Mid Atlantic Luthiers on the internet .
Here is a nice french polish tutorial as well.
Here's one that goes into alot of detail from an older thread..
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There is one major difference that I can see in the technique posted and displayed on the Mid Atlantic Luthiers website and it is a big difference .
It has to do with using de-waxed shellac or not and as whether or not to use any oil in the process of application of the shellac .
I am asking for people interested to view and comment , please .
Thank you .
dewaxed = clearer finish
waxed = softer lustre, higher durability (it is more plastic, and less brittle.)
You can verify this by pouring out small samples of waxy and dewaxed onto a glass surface then allowing them to dry. Then you can easily scrape/peel up the resulting films and inspect/test them.
He's correct that back in the day shellac was it for finishing furniture & floors.
I disagree with his assertion that dewaxed is more resistant to water. More the opposite.
But the reason waxed shellac is more prone to showing the water ring is due to it better trapping moisture under the film, and the visual interaction between moisture and the wax present in the film.
Shellac was primarily dewaxed as a form of standardization and to simplify commercial processes - waxed shellac will separate on standing and needs to be re-mixed prior to use.
What about his claim that oil is not used or needed with shellac containing wax ?
I do see some real advantage to this .
Oil is never absolutely necessary, regardless of the shellac used. it merely makes the process less prone to error.
The danger of not using oil is during the building phase. If you pass over a recently applied area that has not had time to flash dry then the pad will stick to the softened surface. If you limit your build sessions to only a couple layers, use a very light touch, and work quickly you can get by without oil.
Waxy may be less prone to sticking than de-waxed, but this is still going to prove highly variable, and if anything all shellac is just plain sticky stuff.
If you are going for a super thin finish then the little bit of oil used is not a major concern - use a sparing amount and it will always stay on the surface to be easily spirited off.
If you are going for a thicker build and are worried about oil accumulating in the film then save yourself a lot of time and effort and learn to brush on shellac. Thick builds using a pad almost always require block sanding anyway. So brush it on, allow to fully dry, then block sand level. At that point you can either polish the surface or pad on the final layer for the more traditional final appearance.
True french polish technique is wonderful, but was developed in an era before the widespread availability of backed abrasives (sandpaper) as such it is outmoded (just like silica grain filling has been superceded by any number of better and easier approaches.) Unless you are dead set on doing a period reproduction, or working with very complex surfaces (like carved finials, or turnings) there is not much reason to stick with full traditional technique.
just used dewaxed blond flakes to refin an accoustic guitar sound board
first time i used shellac and it was a steep learning curve initially but relaxed into the vibe quickly -
i found it easy to mix
leave it in a jar with enough metho to just cover the flakes for 3 days
complete breakdown with no residue
break it down then with an equal volume of metho to make a mix the consisteny of pee may be a bit heavier but quite thin - about the same colour
i just wiped it on as evenly as i could with a pad of old cotton - speed essential once its on don't go back over it - i could apply maybe 6 - 8 times a day - after 3 days i had a decent build
just went over it with 600 grit wet n dry to level and buffed it with 0000 steel wool - good enough for this job - pretty easy in fact - a nice soft satin sheen
buff and polish
although i didnt do it i could have kept going with finer grits and cutting compund to get a pretty decent gloss i reckon
getting it off where it isnt spose to be
a pain - i found metho got most of it - soften and scrape - clean up with clear amononia
good stuff i reckon exept it is no good if you dump a load of scotch on it