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| OK Repair gurus, bail me out.... http://luthiersforum.com/forum/viewtopic.php?f=10101&t=39598 |
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| Author: | Jaybird840 [ Mon Mar 04, 2013 8:51 pm ] |
| Post subject: | OK Repair gurus, bail me out.... |
Hi Guys, I undertook a repair for a friend with the understanding that I'm not an experienced repair guy. Typical bridge split on a Guild. I used a heated putty knife that I thinned at the end. The bridge came off just fine, but the black lacquer on the top wasn't so happy with the heat. Not sure if it was when I pulled the tape, or if it just wrinkled a little due to the heat. So, two questions..... 1) I realize it won't go back to perfect, but what can I do to mitigate/minimize the wrinkling? 2) There is a chip missing in the black lacquer on the leading edge of the bridge from when it originally split (prior to me removing the bridge). Is there a drop-fill technique or similar that I can use to hide that blemish? Thanks all!! Attachment: 2013-03-04 19.13.29.jpg --Jaybird |
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| Author: | Kent Wilkinson [ Mon Mar 04, 2013 9:27 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
I did the same thing on a Uke. Will softner work? |
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| Author: | John Coloccia [ Tue Mar 05, 2013 2:32 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
What you have going for you is that the rest of the finish is in bad shape too, so that makes it a little easier. Please say this is a US made Guild...I believe they all used nitro finishes and that will make everything easier to repair. This may take some experimenting, but the problem is that it can go from bad to worse very quickly. The first thing you want to do is try cleaning the area with naphtha. If you're REALLY lucky, all you're seeing is glue from whatever tape you used, and it's maybe just tenacious because you melted it onto the finish. But you probably melted the lacquer. I think you may have to work out the melted bits of lacquer with abrasive...micromesh would be my choice. Then you're going to need to hope and pray that you don't burn through the finish because who knows how thick it is at this point. I would even consider doing a little experiment with a small drop of lacquer to see if that would help the situation any. If I could cosmetically fix it by adding lacquer, I would definitely consider airbrushing the area, and then micromeshing that to match the rest of the guitar. That would take a little bit of the pressure off trying to fix lacquer in an unknown state. For the bridge, there are a number of techniques. You can always drop fill with tinted lacquer. My first choice, assuming it's not a big chip, would be to order black CA from StewMac, and do the drop fill with that. Level, buff and it will be invisible. |
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| Author: | John Coloccia [ Tue Mar 05, 2013 8:32 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
I sort of agree with Filippo, actually. Like I said in my original post, this can go from bad to REALLY bad in the blink of an eye. It's really completely unknown what state that lacquer's in and you could be one swipe away from disaster in spots. |
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| Author: | Dave Baley [ Tue Mar 05, 2013 11:29 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
I saw a demo of something called amalgamator. Would that help here? |
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| Author: | Alain Moisan [ Tue Mar 05, 2013 11:56 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Although I don't consider myself a repair guru, here's what I would do. Sand smooth the areas that you damaged. Then apply black paint on those area. Sand smooth again but without sanding through. Apply shellac to insure proper adhesion. Than apply some laquer, sand smooth and polish. if the finish is indeed laquer, than it should blend in quite well (no winess lines). You may be able to differenciate the two tones of black, but it should be pretty subtile. Black under polished finished is always black. Here are 'before' and 'after' shots of something similar I did in the past. Attachment: DSCN8619.JPG Attachment: DSCN8677.JPG Hope this helps! |
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| Author: | John Coloccia [ Tue Mar 05, 2013 11:59 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
I've never heard of a specific product called amalgamater that, but it's probably just lacquer thinner. Maybe it's cut with something to make it a bit less volatile, and maybe a bit of retarder. There are other similar products. One is called "blush remover", and again it's just thinner and retarder. My personal choice if I were to do anything is to try adding a bit of lacquer first and see what that does. Just adding thinner could well end up with a big mess and bare spots. You really need to see it in person to judge what needs to happen. Filippo's advice is very wise, though. |
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| Author: | B. Howard [ Tue Mar 05, 2013 12:32 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Do not try anything more than cleaning with something like DA until you determine what type of finish you are working with. Lacquer will not stuck well to most poly and will leave witness marks. Do a composition test first to determine what you are working with. If you do not know how to do that, seek out some professional help in your area. You stand a really good chance of making bad situation worse |
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| Author: | B. Howard [ Tue Mar 05, 2013 12:34 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Also, FWIW, black isn't always black......Lincoln added a tad of violet to their black years ago, it made their cars look a little richer in finish when parked next to a Cadillac. |
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| Author: | Alain Moisan [ Tue Mar 05, 2013 1:50 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Todd Stock wrote: Mask the bridge area. Touch up any chips with black-tinted lacquer (black dye and clear lacquer). If you've managed to lift the lacquer from the top, time to mask the bridge and respray the black after removing any separated lacquer, If all you've done is wrinkle the top coats (that's what it looks like), just shoot the area around the bridge with a couple of fairly heavy coats of clear and let them soften and melt everything together. Allow to dry 2-3 weeks, sand level and buff the area. Remove the bridge patch mask, clean the patch (I rout down to clean wood (usually .002-.003) and rabbet the bridge as a matter of course on non-vintage stuff. All this is good stuff, although I would first make sure it is lacquer you are dealing with (Light tap with a Q-tip dipped in acetone. If it desolves the finish, it's lacquer). If the finish is some sort of polyesther or polyurethane, nothing will melt together. You will be better off sanding the wrinkles away before you start doing the touch ups. And regarding withness lines, if it is anything but lacquer, you WILL have winess lines. So don't spend too much energy trying to avoid them. |
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| Author: | jfmckenna [ Tue Mar 05, 2013 4:20 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Being black is a blessing as it will make it a lot easier to hide. I am no expert at repairing lacquer but I would have thought a simple wet sand and polish would bring it back. The finish on that guitar is probably plenty thick enough but since I don't have the guitar in my hands then I don't really know. If the wet sand and polish doesn't work then black lacquer on top as Todd outlined will work. BTW You didn't exactly describe how you removed the bridge but a couple things to note is you don't need to heat up the spatula usually and if you put a little bend in the tip of it then it helps keep it off the top. Good luck. |
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| Author: | Jaybird840 [ Tue Mar 05, 2013 10:13 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Thank you all for your replies. It is an early Guild, and I'm 95% positive it's nitro, but I'll test to be sure. My plan is to work the wrinkles down a bit with micromesh, mask, and shoot a couple coats of nitro to blend it back together. Any issues with using an airbrush to shoot the nitro? With that in mind, is there a ready source for small amounts of nitro? I have a Hobby Town (RC Airplane shop) and a Hobby Lobby (think quilting) reasonably close as well as the BORG/Lowes. All they seem to have is tinted lacquer, tho.... I can get Behlen's at my local woodcraft, but would prolly end up throwing a bunch out after it goes bad. I guess I could experiment with a nitro finish on my next build (or build that telecaster I've been thinking about). I guess I could try the Re-Ranch products too, but hate to mail order something... Anyway, I look forward to learning how to un-bungle this one. It will serve me well in the future. --Jay |
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| Author: | Dave Baley [ Wed Mar 06, 2013 12:27 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
John Coloccia wrote: I've never heard of a specific product called amalgamater that, but it's probably just lacquer thinner. Maybe it's cut with something to make it a bit less volatile, and maybe a bit of retarder. There are other similar products. One is called "blush remover", and again it's just thinner and retarder. . This is the same thing I saw. http://www.frets.com/FretsPages/Luthier ... ator1.html This is the exact material. It says it repairs heat checked lacquer. I do not have any personal experience with it, just passing the info along http://www.mohawk-finishing.com/catalog ... ictNbr=137 |
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| Author: | nyazzip [ Wed Mar 06, 2013 1:54 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Quote: but would prolly end up throwing a bunch out after it goes bad ...last winter i discovered a small can of nitrocellulose laquer that my father bought back in the mid or late '60s. it had stratified and looked awful. but, i gave it a good stir and tried it, and it was/is still fine. you might be surprised; don't by the hype about shelf life, because most of the time it is BS. i definitely wouldn't hesitate to use nitro or shellac that was 10-15 years old, as long as it was stored in a climate controlled(ie inside) location |
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| Author: | John Coloccia [ Wed Mar 06, 2013 2:59 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
As far as I know, nitro has no shelf life. Without exaggeration I suspect you could take an old guitar, scrape the finish off into a little mixing cup, mix it with lacquer thinner and respray it if you really wanted to. Shellac does have a shelf life, though. If it's already mixed, you're lucky if you get a year. In flake form, I'm not sure what the life is, but I do know that people have had problems getting old bags of flakes to dissolve though I've personally never experienced that. |
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| Author: | nyazzip [ Wed Mar 06, 2013 11:06 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
not to hijack, but what are the symptoms of "expired"/bad shellac? does it remain tacky forever....?i have a can of amber Bulls Eye or Zinser, i can't recall, that is 4-5 years old, i've been using it here and there on small stuff |
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| Author: | Michael.N. [ Wed Mar 06, 2013 11:21 am ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
It remains soft and gummy. Shelf life of dry shellac flakes depends on the type. I have some seedlac that is near 20 years old and is fine. The more refined bleached grades are the type with a shorter shelf life. |
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| Author: | John Coloccia [ Wed Mar 06, 2013 12:53 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
The classic test is put a drop on a piece of glass (or something else non-porous). If it hardens, you're good. If it doesn't, toss it. Best, though, is just mix it fresh when you need it. I picked up a coffee grinder for $2 at a yard sale. I use that to grind up my flakes, I measure by weight on a cheap Harbor Freight scale, and my shellac is fully dissolved in an hour or two. I only mix up enough to use over the next week or so. |
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| Author: | Jaybird840 [ Tue Apr 09, 2013 7:32 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Hi All, Thanks for all the advice! I eventually determined it was a lacquer finish, and used a process of drop-fill, micromesh, blush remover, and auto polishing compound. Repair came out pretty good. The owner had no complaints! Here's how it turned out.... Attachment: 2013-03-29 11.12.46.jpg And so, for my efforts and a $100 bill, I walked away with this.... '68 J-45 Deluxe--finish is pristine (celluloid binding is wasted, neck set is bad (of course) and the bridge has been reglued or replaced), but it should make a good axe after some tinkering! Thanks for the help, peeps! Attachment: 2013-04-09 19.28.40.jpg
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| Author: | Clinchriver [ Tue Apr 09, 2013 7:41 pm ] |
| Post subject: | Re: OK Repair gurus, bail me out.... |
Nice score, love a trade! |
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