Official Luthiers Forum!
http://www.luthiersforum.com/forum/

Going from lacquer to french polish.
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=35990		 Page 1 of 1
Author:  Catgutter [ Sun Apr 01, 2012 2:18 pm ]
Post subject:  Going from lacquer to french polish.
Hello forum.
As the title suggests, I would like to remove all the lacquer from my classical guitar and french polish it. (I can already hear people saying "You're crazy! Don't do it!") The guitar is an all-solid cedar-on-rosewood Lucida-777 classical. It's not hugely expensive but not a cheapie either. I would like to improve the volume and tonal characteristics as well as use it as a test bed for future FP projects.

Should I sand or use a chemical solvent to remove the lacquer? I've read elsewhere that some factory finishes such as polyester will not react with solvent and I don't want to turn the lacquer into soft goop.

If I sand away the top stain, what stain should I use to replace it with and what preparation will it need? Will any good hardware store stain do, like Minwax, and should it be sealed in some way prior to applying shellac?

How best to protect the rosette? I can carefully fine sand down to the rosette level but how will the rosette take to being french polished? Thanks in advance.
Author:  woodrat [ Sun Apr 01, 2012 3:05 pm ]
Post subject:  Re: Going from lacquer to french polish.
G'day Catgutter, I dont know if this will help but I just stripped a damaged guitar that I made and it had nitro lacquer on it and I heated it with an iron before scraping it off. There is a magic temp where the lacquer just lets go and you can scrape it off easily. See the pics of what I did and see if it might work for you. I didnt have a go at the spruce top though so I dont know how it would go on that....I just removed the top as you will see in the pics....

Hope it helps...

John

http://www.anzlf.com/viewtopic.php?f=1&t=4181
Author:  Catgutter [ Sun Apr 01, 2012 3:42 pm ]
Post subject:  Re: Going from lacquer to french polish.
Hi there John. Thanks for the tip. It looks a bit scary though. I'm not sure I'm brave enough to do that, especially to the topside. Sure wouldn't want to melt any glue. I might have a go at the sides as see what happens, maybe with a heat gun on 'low'. It could save a number of hours of sanding.
Author:  woodrat [ Sun Apr 01, 2012 4:22 pm ]
Post subject:  Re: Going from lacquer to french polish.
Hi Catgutter, it was really not that scary once I realised that at the right temp the stuff really just falls off. I used a palette knife to take it off...
...another option to consider is a sharp card scraper , the nitro will yield to that too.

Hope it goes well for you...YMMV but it worked for me:)

John

BTW...you wont melt any glue...it will get thermoplastic at much higher temperatures than what it took to get the lacquer to let go.
Author:  Catgutter [ Sun Apr 01, 2012 5:15 pm ]
Post subject:  Re: Going from lacquer to french polish.
Thanks again John. I'll give it a go, working up the temperature until the lacquer begins to surrender.
Author:  woodrat [ Sun Apr 01, 2012 5:38 pm ]
Post subject:  Re: Going from lacquer to french polish.
CG, Make sure you start on the back to get the feel for the temp at which the lacquer will surrender....I have not tried a heat gun (dont have one) but that could be just as effective....but there may be a difference with radiant heat vs air heat....not sure about that either....

John
Author:  TRein [ Sun Apr 01, 2012 10:17 pm ]
Post subject:  Re: Going from lacquer to french polish.
Hold on a minute. I am not sure where Lucida guitars are made, but I doubt whether they use a nitro finish. Far more likely to be a catalyzed finish, IMO. You may want to contact them first to see if they can give you any info.
Author:  Catgutter [ Mon Apr 02, 2012 12:56 am ]
Post subject:  Re: Going from lacquer to french polish.
TRein wrote:
Hold on a minute. I am not sure where Lucida guitars are made, but I doubt whether they use a nitro finish. Far more likely to be a catalyzed finish, IMO. You may want to contact them first to see if they can give you any info.


Thank you for the advice. They are made in Spain, probably a side brand by a major factory. I've tried contacting them but to no avail. No worries, I can always dig in with sandpaper. The Artista-777 is actually a nicely constructed instrument IMHO, at least for a $1000 retail guitar, only it does lack volume. I think it would open up and show more potential without the lacquer on it.
Author:  woodrat [ Mon Apr 02, 2012 1:03 am ]
Post subject:  Re: Going from lacquer to french polish.
CG, I think that the removal method that I used will work for you on the back and sides with no dangers but the cedar is soft with a capital S....I think you would remove it faster with a freshly sharpened cabinet scraper...I didnt have to worry about the top as I know it was to be trashed and a new top put on but you are trying to save it.

Cheers

John
Author:  Catgutter [ Mon Apr 02, 2012 4:20 am ]
Post subject:  Re: Going from lacquer to french polish.
The cabinet scraper sounds more scary than the heat. :o
I appreciate and respect your advice though, so I don't mind giving it a try, but I also don't mind taking a slower course of action. I want to expose the bare wood anyway so sanding is going to occur at some point. Should the scraper be used on pre-heated loose flakey lacquer or on the lacquer as it is? It sounds like I could puncture the top.

When all the goop is scraped, chiseled, burned and otherwise done away with, what other steps should I take before the initial french polish? I especially don't want to ruin the rosette and I'm wondering about the stain - if it will be necessary to apply new stain and if so, what kind, and how the shellac will take to the stain surface.
Author:  woodrat [ Mon Apr 02, 2012 6:58 am ]
Post subject:  Re: Going from lacquer to french polish.
Hi again CG....I cant claim that I am overly experienced at this although I have done this instrument successfully upon some experimentation but that did not include the softwood top, I just ripped it off with a jigsaw. So yours is different in that it involved this more delicate step. If you worked methodically with a very sharp, repeat, very sharp scraper then I believe you would be able to succeed in the lacquer removal of the top. Scraping is such a great technique and I use it for so many things in my instrument making so that is why I would give it a go...slowly and methodically and I would try to take it all down as level as possible too and probably sand the last remnants of lacquer.

Regards and I hope it goes well for you...

John
Author:  Mike OMelia [ Mon Apr 02, 2012 7:38 am ]
Post subject:  Re: Going from lacquer to french polish.
Whether its lacquer or polyester, a heat gun will do the trick and not loosen any spars. Look on YouTube for videos. If it is polyester, sanding will be the last approach you will want to try. That is tough stuff.

Mike
Author:  Mike OMelia [ Mon Apr 02, 2012 11:26 am ]
Post subject:  Re: Going from lacquer to french polish.
I just picked up on a hint that this may be your first attempt at something like this. Todd's advice is good and sound. I would take the heat gun (sort of a hair dryer on steroids) approach. Watch some YouTube videos. With a few seconds of exposure, the surface will bubble up and you can gently scrape that off (lacquer or polyester). I have no idea what will chemically dissolve polyester. Strong solvents can be dangerous for your health. You should wear a respirator or good mask. If you use heat, do in a well ventilated area so you don't breath fumes. You can tell if it's nitro by rubbing surface with acetone. If it is some kind of polyester (likely), then acetone will do nothing to it. And if you attempt to sand it off (and it is polyester), plan to spend a long time doing it. And wear a mask.

Since you are apparently new to this, don't be surprised if the end result is less than you expected. Plug the soundhole so no residue builds up on inside of guitar. Finally, a FP is an art unto itself. Meaning you are going to have to ask a lot of questions and learn some new skills.

And all of this on top of the question of whether it's really worth the effort!

Mike
Author:  Bryan Bear [ Mon Apr 02, 2012 4:59 pm ]
Post subject:  Re: Going from lacquer to french polish.
I strongly suggest you reconsider doing this. The questions you are asking lead me to believe you have never attempted anything like this before. This is probably not the instrument to go through the growing pains of sanding, prepping and finishing. Further, I doubt that changing the finish will give you a huge boost tonally and you almost certainly will be disappointed visually.

I'm not trying to be a downer here. There is no reason to rush into this operation. Go out and buy a broken flea market guitar. It will likely have a poly finish too. Strip it down (if the box is broken, get some repair practice while you're at it) and refinish with french polish. Then re-evaluate your plan. I did this exercise once; I'm glad I did. I'm even more glad I did it on a free guitar with a broken neck. It is playable now but it is best suited for camping (around the fire after the sun has set).
Author:  Catgutter [ Mon Apr 02, 2012 9:02 pm ]
Post subject:  Re: Going from lacquer to french polish.
Thanks Woodrat, TRein, Todd, Mike, Bryan,..

Bryan, you successfully talked me out of it. I'll leave it alone, at least until I've experimented on that $5 yard sale folk guitar.

If you want to know who's to blame for giving me this insane idea in the first place:

http://www.youtube.com/watch?v=lsGTJlLACYg

But seriously, Mr. Thames has been at this for years and knows what he's doing. Speaking of tonality, he elaborates on the pros and cons of FP and lacquer at part-3, 0:56. I feel my guitar would benefit from a more open sound with better volume but I'll heed the caution and learn the skills first. The desire to FP is still there. It must be very satisfying to polish your own guitar in such a way.
Author:  Bryan Bear [ Mon Apr 02, 2012 9:31 pm ]
Post subject:  Re: Going from lacquer to french polish.
Good on ya. You will learn a lot by practicing on a junker and you'll be glad you did. If/when you refinish your guitar the results can only be better.
Author:  Tai Fu [ Wed Apr 04, 2012 2:12 am ]
Post subject:  Re: Going from lacquer to french polish.
French polish ain't rocket science, you just need a lot of patience and elbow grease.

Plus if you do mess up you can always sand the high spots, and french polish over the low spot until it disappears... its really easy to blend french polish, even easier than lacquer.

The difficulty in this exercise is taking off the old finish without affecting the structure of the guitar. You are going to lose some wood no matter the method you use to strip the old finish, since you still have to sand away parts of the wood that has soaked up some finish. This may or may not contribute to improved tone when changing over to french polish.

I say go for it, if it is lacquer (test it with acetone) then you can chemical strip it, but if its anything else like conversion varnish, pre-cat, etc. then the only choice is sand it off. I would not use a heat gun, you run the risk of doing more damage to the guitar. While people on reranch forum has suggested heat gun to strip polyester, remember they're mostly refinishing electric guitars which are more durable compared to a classical guitar, plus polyester requires a bit more heat than any other finish/sealers to release... they have often reported that the top coat comes off easily but the polyester sealer requires much more effort to strip with a heat gun.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/