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RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
quote:
French polish over a very thin layer of sprayed Nitrocellulose:
Sealing with nitro, sanding, porefilling with nitro pore filler, sanding back, color with nitro, sanding, 1layer of nitro, sanding, French polishing.
Well some thoughts against doing this: Basic finish wisdom is, nitro over shellac sealer, not shellac over nitro sealer.
I've seen guitars done this way have peeling finishes. And as long as you are that far into a nitro finish why stop and French polish? It defeats the point of either finish.
The other thing is that it takes longer for nitro to condition before you can cut it back and level, so you will have two materials which will be shrinking at different rates while you work. Unless this guy shows you exactly how he does it I would not do this.
If your idea is to get a color coat and then French polish you can brush or spray shellac clear, pore fill with pumice or whatever, spray or brush more clear to seal the filler. Then level. Then spray shellac with color and then body it up with a pad and carefully move to rubbing out and glazing it.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
I thought the object was to keep the Nitro as thin as possible anyway so as not to effect the sound in a negative manner. How the heck is adding FP on top of Nitro going to improve the sound over a pure Nitro application? Easier, faster and less complicated to apply this combined finish then a pure FP? French polish on the outside is still only as strong and durable as FB can be and will still be effected by things like sweat etc. Easier=fail Superior sounding=fail Harder finish=1/2 fail under coat of Nitro will be Calling it french polish= a huge fail for dishonesty
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
As Steven said shellac makes a great wood sealer and nitro on top is a more logical way to go. I have also heard shellac will flake off of nitro probably because of the different shrinkage rate as Steven mention but I have not tried this method as it makes no sense to me whatsoever. Manuel Reyes french polished his own guitars and I read an interview with him where he stated the above mentioned method by Steven of spraying on the shellac and then finishing the job with a FP. This must be an acceptable way of speeding up the FP process as I have not heard any bad things about the finishes of M Reyes guitars over the long history he has has of making them.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
Fp doesnt Doesnt stick to everything I know of examples in finishing where this has not worked out. I know it does not stick to an epoxy resin particually well and I know it does not stick to polyurathane either. Think of it like this. Seal two pieces of wood with shellac then stick them together with titebond. This should hold. try and stick two well French polished pieces together and you will have no luck.
If it's a mix you are after go for nitro back sides and neck and a fp top.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
I'm with Steven on this one. I have in my restoration work had to fp over oil varnish as well as lacquer and it isn't something I would do on a new guitar. In those cases where I have done it is simply for the reason that it is reversable and it's the only thing I can do short of a complete refinish (or hire out someone to spray lacquer, varnish or whatever).
The shellac sticks kind of but it doesn't really bond to the lacquer or varnish. In the violin world they often do it to protect the oil varnish underneath, in repair work, and in new work...to make it look like an older fiddle that has been around (and been worked on).
In any case with any handling the shellac will wear off, or orange peel as they say, where you can clearly see where the shellac is sitting on the surface, and where it isn't
If you want to shoot a thin coat of lacquer over the shellac that should work fine. In any case I would sooner lacquer the back, sides and neck and then fp the top. Or more likely use a catalyzed urethane like the Ramirez finish, or more likely than that, the newer uv cured finishes that have been getting very popular with the steelstring crowd. Some I've seen have been quite impressive. But I wouldn't switch from fp for the top.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
My understanding is that the reason you would want a shellac sealer under nitro is to keep oily woods from bleeding color with nitro. And to protect the wood from whatever you use as a pore filler.
When FP I spot seal woods that bleed color with a brush and do careful line work to separate areas. When that gets sealed I move to the other FP techniques. I'm not a big nitro sprayer, but my friends who use it do the same thing by prepping with shellac and then spray lacquer.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
Kevin,
The chance that I will get on with this new system is 2%. Especially after reading this thread.
Very good. Thanks. Its good to see the forum is working 100%.
I like FP, but it has its bad sides. Its a lot of work to aply, especially the porefilling and its not the strongest of finishes to say the least. Its also not the best finish for coloring. ETC.
I actually like nitro a lot if its well done. Its backdraw is its fumes and that its highly inflamable. Besides that, it looks like its going to be banned (for those reasons) here in Europe
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
So, all is good or is it??
I would like to question a few things.
1) Your opinions, are they based on something you have tried, is it information from someone really competent or is it myth? When professional talk, it often ends up being very incrowded and conservatism often rules.
2) Shellack will peel off.. Why? If you make a good mechanical bond (sanding with 180 - 240 grit) Then I cant see why shellack shouldnt stick to nitro. Ihave actually tried it a few years ago on a piece of scrap and nothing went wrong.
Shellack sticks to most 1 component things. It even sticks to vinyl and some say it sticks to silicone (nothing else does) So did you guys test this or do you have it from a source that can be trusted or is it just something you heard (myth). Lets keep epoxy out of this. Just nitro below shellack. I know epoxy from boats and it can be really troublesome. but funny enough, shellack is actually used as a sealer when epoxy goes trouble. (after letting epoxy air out some weeks and washing it down with a strong soap)
3) The idea is a very thin layer of nitro, almost sanded away.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
For what it´s worth ( as not involving nitro ): I had asked a luthier to peel off DD laquer from an old guitar and refinish it. Laquer ( nitro as I had thought ) for back and sides and FP for the top.
What he did instead was applying a thin layer of resin laquer ( "0,2-0,4 mm" according to him ) to both B&S and top and cover it with shellack ("max. 0,2 mm"). I wasn´t really fond of him doing so; originally intending to avoid FP on B&S for the disadvantages it has when in contact with ( sweaty ) skin. ( Summers are very hot over here.) Further, I suppose that he might have proceeded so for lack of a spraying cabine ( unable to avoid dust pimples with laquer ); hence the final layer of FP.
So far, however ( summer´s gotta come yet ) the finish seems to be fine in regard of resonanting properties of the corpus; and there are no signs of the layers separating. In the opposite, they seem to bound rather well, considering how much both layers have conjunctly sunken into the woods grain lines.
Maybe it is too early to tell though, considering that the new finish is being only 8 months old.
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
If the outer layers of the finish are shellac then those outer layers will share the weakness of durability as any pure FP shellac finish will. I don't see how this whole process can really be a time or labour saver. Nitro is getting more scarce and do to legislation will soon be a thing of the past anways.
Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
Another problem with the proposed schedule is the "porefilling with nitro porefiller" I have never actually heard of this product. If you are talking nitro based sanding sealer then it does not do a very good job of porefilling and many people have found it gives adhesion problems for the next coat Most people dong nitro finishes are porefilling with something else such as epoxy, oil based filler or water based filler. If you try to use nitro to fill pores it takes a lot of coats and then continues to shrink back for months after
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
Anders, on my current batch I am doing one pure Nitro, (Pimientitos negra) one nitro back sides and neck with FP front and one same but FP over the nitro. I have done this before, just needs to be well cured so time wise it takes a while. I once sprayed FP , deadly as its so tempting to put a lot on, nice wet spray coats like nitro but then it cracks like crazy 6 months laer, like a thin sheet of hard ice on top of a syrupy lake..
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
Yo Stephen!! good to see you here. Have you got a full spray kit? useful for your course I bet.
Anders - My first answer was a question asking wether it would stick or not. My latter reply was that I know FP doesnt stick to things like PU and Epoxy as I have had experience with this.
No conservatism or myth in my answers. Perhaps the differing shrinkage rates woud be the only problem
RE: Want your opinions on alternativ... (in reply to stephen hill)
quote:
ORIGINAL: stephen hill
I once sprayed FP , deadly as its so tempting to put a lot on, nice wet spray coats like nitro but then it cracks like crazy 6 months laer, like a thin sheet of hard ice on top of a syrupy lake..
If interested in this method, you could ask Amalio Burguet. ( He replies only to inquiries in Spanish language, though.) I have one of his top of the line classicals, which if I recall that correctly, was finished with sprayed shellack. It´s five years now that I own it, and it shows no cracks.
Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
It is a mistake to think that nitro lacquer will solve your porefilling issues. And nitrobased sanding sealer is not a good idea. That is my experience not myth.
Once you get a good porefill, thin niro is great and needs no topcoat with shellac IMHO.
Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia
RE: Want your opinions on alternativ... (in reply to Anders Eliasson)
Well firstly there is not such a thing as nitro based porefiller to my knowledge, there is only sanding sealer which is nitro with solids content which is not designed to fill pores, only minor surface imperfections. Sanding sealer unfortunately can give adhesion problems for the top coat, and I will not use it again for this reason. The other problem with trying to fill pores with a nitro based product is that every coat you apply puts more solvent into those below, and that solvent has to eventually find it's way out, and then months later you have pores appearing in your nicely leveled surface. That is why you need to do the porefill first with a high solids paste filler (or epoxy) so that you have the pores filled with a stable material which the nitro will not just reactivate
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