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Brushing french polish
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Author:  PeterF [ Thu Apr 17, 2014 5:28 pm ]
Post subject:  Brushing french polish

I've just come across this product http://www.slhardwoods.co.uk/products/p ... nch-polish
Has anyone tried it? It looks like a way of getting a french polish finish a lot quicker and easier... idunno

Author:  Pat Hawley [ Thu Apr 17, 2014 5:47 pm ]
Post subject:  Re: Brushing french polish

I haven't tried but find it's name mis-leading as it implies that "French Polish" is some kind of finish rather than a technique.

Pat

Author:  RusRob [ Thu Apr 17, 2014 5:58 pm ]
Post subject:  Re: Brushing french polish

Yes I believe that would be called shellacking, French Polishing is done with shellac, alcohol and mineral oil and is applied with a rubber (or mouse) by hand.

I am not sure how that terminology came to mean applying shellac with a brush and then sanding it down only to rub it out with compound to get it to shine. I guess it came about because brushing is easy and French Polishing takes skill, time and is far from easy and they wanted to make it sound better than shellacking... idunno

Bob

Author:  Greg B [ Thu Apr 17, 2014 6:27 pm ]
Post subject:  Re: Brushing french polish

+1 Yeah, that's an oxymoron for sure. French polish means shellac applied with a rubber.

Brushing shellac (AKA shellacking) works fine. It takes longer but requires less practice and skill, and results in a thicker finish. Waxed shellac is IME better for brushing.

I guess one could argue that brushing carved work with a fine brush and thinned shellac is officially part of the technique, but this doesn't apply to most guitar building.

Author:  TRein [ Thu Apr 17, 2014 8:16 pm ]
Post subject:  Re: Brushing french polish

I would not buy it without having access to the MSDS. I would not be surprised to see some nitrocellulose lurking in there. There may be some shellac in it as well, but if combined with nitro there will most likely be nasty stuff like butyl cellosolve in the mix.

Author:  B. Howard [ Fri Apr 18, 2014 7:01 am ]
Post subject:  Re: Brushing french polish

French Polish is a technique whereby shellac is compacted into a very tough and thin film via application involving pressure. A brush cannot produce those results.......You may sparay or brush shellac, but that is not the same as a French Polished finish. The film will be much thicker and less dense.

Author:  Michael.N. [ Fri Apr 18, 2014 7:32 am ]
Post subject:  Re: Brushing french polish

I brush Shellac but use the 1704 recipe or rather close to it. I've never gone along with the claims that using the fad somehow results in a denser film. It is true that it is much easier to get a very thin film with the French polishing technique though. That's where I believe the main difference lies. A thin film of Shellac will harden much faster than a thick one. I have a test piece with the 1704 which must be near 3 years old. It's actually quite a hard and tough finish. Shellac goes on changing for decades after it's applied, which is why certain types eventually become impervious to it's original solvent. Brushing on coats of Shellac is very quick but you pay for it in the time that it takes to become truly hard. So if you can ship a Guitar 1 month after finishing with FP, factor in around 2 months + for a brushed on finish.
Liberon also do a brushing 'French Polish'. If you look at the manufacturers data sheet it's just Shellac with an extender added. The Spike Oil in the 1704 recipe does something similar. Some people add a mere touch of turps.

Author:  Clay S. [ Fri Apr 18, 2014 7:38 am ]
Post subject:  Re: Brushing french polish

Brushed shellac tends to stay sticky longer and attract dust - one reason it is an ingredient for making tack rags.

Author:  Michael.N. [ Fri Apr 18, 2014 7:51 am ]
Post subject:  Re: Brushing french polish

The dust isn't a problem. Dust and Oil varnish certainly but not brushed shellac.

Author:  jfmckenna [ Fri Apr 18, 2014 8:33 am ]
Post subject:  Re: Brushing french polish

FWIW I brush on about 3 or four coats of shellac and sand back before French Polishing. I think it gives a nice head start and builds up a base for the FP technique to glide along easier. It also seals in any woods that might bleed like rosewood bindings.

Author:  PeterF [ Fri Apr 18, 2014 4:26 pm ]
Post subject:  Re: Brushing french polish

Thanks guys. I thought there must be a catch to it somewhere! I think I'll just stick with oil varnish for now...

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