Got a run in my nitro. Best fix?

[Allan Speers]

Hey folks.

I'm not much an instrument builder, but I needed to touch-up spray some nitro on one of my guitars, over the existing nitro finish. I was feeling lazy (AKA "foolish) and decided to just use Deft spray-can stuff. It says it's 100% nitro, and the adjustable nozzle gives a fairly decent spray.

So far I only did 2 light coats, 30 minutes apart. It needs more, of course. - but I already got a little run in the middle of the body, about 2" long.

What's the best way to remove this & procede? Since the new finish is a hair shinier than the original, (Yes, I shook the can like crazy) and I prefer the original, I thought I'd try taking it all down with fine steel wool. Is that a reasonable idea, and would that also remove the run, or should I first use sandpaper?

Any other tips before I finish this thing? It's a valuable guitar (yeah I know, but I'm broke) so all advice is appreciated.

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FWIW - This is a Trussart Steelcaster. - One of the original ones without any mesh in the body. Lovely, and incredible to play due to massive dynamics and overtones. Oh my.... But as you may know, he finishes these by letting them rust, then applies the nitro.

There was a large "distressed" area on the front that I always hated as it was TOO clean, so I finally decided to do something about it. I heated it carefully with a torch so it would quickly rust in that area. (this worked great) and now have to get nitro over that area. The new nitro doesn't quite match the look of the old, so now I've pulled it apart and will do a few light coats over the whole thing.

So.... that's where I'm at.:o

[george wilson]

Snug some 220 grit wet or dry paper onto a flat wood block. Maybe even GLUE the sandpaper to the block. With mildly soapy water,carefully sand the run down. Be VERY careful to not sand through the rest of the finish. It would be even better to make some SMALL sanding blocks up. Say,1" x 1 1/2" and sand with those to focus your sanding even better on the run. If you go through the original finish,the only real cure will be to strip the guitar and refinish it. So,KNOW the consequences of not taking your time and doing your very best.

BY THE WAY,Deft is NOT pure nitro. It is part SANDING SEALER if you read the can. It will not get hard enough to polish to the same high gloss as the rest of the guitar. I'd let it dry for MONTHS before trying to polish it. It actually takes MONTHS,or YEARS for quick drying lacquer to truly get dry. I know this from actual experience.

I had made a guitar that I had rubbed till no grain showed through AT ALL. About 6 months after I made the guitar,grain started showing through. So,I re rubbed it till it was dead smooth again. After another 6 months,the grain was back. Another re rub.

No longer Martin says it takes what? 9 months to make a guitar! Most of that time is letting the nitro get dry enough to give a stable,non shrinking finish. It only takes them a week or 2 at the most to make the guirar. Even back when I had to do EVERYTHING by hand,I could make a classical guitar with binding in 2 weeks. That included planing all the wood by hand,and HAND polishing the guitar's finish. I'd often spend 40 hours doing that.

[Julie Moriarty]

Here's another method that should work: http://www.stewmac.com/How-To/Online_Resources/Finishing/Hiding_an_evil_smile_peghead_break_with_the_Razor_ Blade_Trick.html

Scroll down to "Razor Blade Scraper"

Since nitro layers melt into each other and you're only on coat #2, this method might work for you.

Here's the video

https://www.youtube.com/watch?v=rTVScFJoe24

[george wilson]

Nice video,Julie!!

[Allan Speers]

Yeah, that's pretty amazing.

Thanks to you both.

[george wilson]

I guess it must work,as Dan is a well known repair expert. But,I'd be worried that super glue would not look or polish the same as nitro. I always have just used drops of nitro to fill chips. Keep adding more as the drop keeps shrinking into the cavity. Takes patience,whereas super glue is one and done. It is going to be less noticeable on a super dark finish like that guitar. And,that guitar,being a new one of apparently low price has who knows what kind of finish on it. Probably poly,which would match super glue a lot better than nitro.

Repair is a lot more profitable than building new guitars,and I used to do a lot of repairs. Was even a Gibson authorized repair guy in the 60's. But,I never liked making repairs as it was not being creative to me. I even rebuilt a Martin D 28 old,vintage guitar that was RUN OVER in a grass parking lot at Union Grove fiddler's convention in North Carolina. Splintered in a million pieces. At least it was on grass,and not ground up on stones. The tire went right over the body. I should have taken pictures! Rosewood can be put back together invisibly due to the dark,variegated,spalted grain(It was allowed to spalt before being cut up. Hence the multitude of dark colors).

[Julie Moriarty]

For Allan's purposes I was only suggesting using the razor blade scraper to level the drip marks, and then letting the successive coats of nitro melt and level. Dan's CA trick looked interesting but I agree with you, George, I wouldn't do it on a nice instrument. At the beginning of the video Dan says something to the effect, "if you're lazy, you won't get good results." Dripping nitro, even tinted nitro, would have been the better fix on a quality instrument. It would just take longer to finish.

[george wilson]

The razor blade trick is a good one. Note that he is using the same flat,small sanding blocks I recommended.

I always use a razor sharp chisel to "plane" the drip off,but that does take skill and the razor blade method is safer for most people.

[Allan Speers]

I guess it must work,as Dan is a well known repair expert. But,I'd be worried that super glue would not look or polish the same as nitro.....


Agreed, though it's still pretty amazing he could do that.


Also - It's my understanding that superglue breaks down over time. It's not recommended for important, long-term repairs.

[Allan Speers]

BY THE WAY,Deft is NOT pure nitro. It is part SANDING SEALER if you read the can. It will not get hard enough to polish to the same high gloss as the rest of the guitar. I'd let it dry for MONTHS before trying to polish it. It actually takes MONTHS,or YEARS for quick drying lacquer to truly get dry. I know this from actual experience.


George,

this has really been bugging me, since the stuff is advertised as being pure nitro. I've been Googling until my fingers got numb, and I still can't find a definitive answer, but on a guitar builder's forum it was said that Deft is nitro with UV blockers added, (no mention of grain filler) and that THAT'S why it takes longer to dry.

So, are you sure about the filler? My can says:
Acetone, Propane, MEK ( ! ) , Cellulose Nitrate, (that's the nitro) Propanol, MIK, V.M. and P Naptha, then a few more solvents.
Wow, so much for "pure" nitro, but are any of those fillers? Is it the Naptha?


BTW, on that same guitar builder's forum, it was said that you have to wait at least FOUR MONTHS before sanding Deft!
OMG, never again.
I just hope it eventually dries as hard as the pure stuff, otherwise it could slightly hamper the guitar's HF vibrations. I'm worried enough about that Naptha (which is 55% wax) that I might strip the body and start over, but that will also require re-rusting the thing, which would be a lot of work.

[george wilson]

I read something somewhere long ago that said Deft also contained sanding sealer. The sealer is just tiny cellulose fibers. I like to stay entirely away from sanding sealer for a few reasons: 1; It is soft. 2, it does take a long time to get good and hard. But,as I mentioned in post #2,the whole finish keeps shrinking for many months. What I use as a sealer is 5 minute epoxy thinned with alcohol Brushed on. When it gets "leather hard" in about an hour(the alcohol sows down the drying time),I sand it with 220 garnet paper. It beads up like tiny "foot balls" and is easily wiped off. Repeat as needed. I don't need anything else on maple or spruce. On rosewood,a filler can be used first.

This process enables me to get a piano finish with a LOT fewer coats of lacquer,which greatly helps the tone. I can get by with 3 or 4 coats. That epoxy does not shrink after it is dry,nor melt under the lacquer. My last guitar was a cannon. Google Uke Jon(John?) to hear him playing one of my guitars. He used to be a young conservationist in Williamsburg when he bought one of my guitars- a round shouldered jumbo with curly maple back and sides. I wish he had my last guitar,though!

It is true that super glue is not permanent. The furniture conservationists in Williamsburg told me to stay away from it. It does deteriorate and is only good for several years. I use it only myself to glue down tricky to clamp small items I'm trying to mill in my milling machine. I glue them down on a brass block(I just happened to have one). When I am done,I heat the piece with a Mapp gas torch till the glue melts. I peel the rest off while it's hot,or put it into a bottle of acetone till it dissolves.

Nitro finishes are rather easy to repair. I bought an old D18 Martin some years ago. The usual pick scratches and nicks,etc. on it. I easily "welded" the pick scratches back together with lacquer thinner,applying it with an artist's brush till they disappeared. Nicks were filled with drops of nitro. They melted the lacquer around them into an invisible "weld" again. Then,I waited for a few months and planed them down with a sharp chisel,sanding with the little sanding blocks with wet or dry glued on. Then,the kit of superfine abrasives like Dan uses in the video. A very handy little box of assorted super fine abrasives. Finally,a hand buff with Meguair's polish.

The guitar looked a lot better,and I traded it for about 3X what I paid for it. I was wanting a few nice amps at the time.

[Julie Moriarty]

Since we're talking about finishing processes...

I adopted the process of using shellac as a sealer. I've experimented with WB dyes that I've sealed with shellac. But if you dissolve the dye in a solvent, like alcohol, you shouldn't use shellac over it, unless you spray it. I noticed shellac had a tendency to gum up my sprayer. The shellac seems to have worked very well as a sealer.

I have used Behlen Instrument lacquer on all the guitars I have built. They all were sealed with shellac prior to spraying with lacquer. Because of the gumming issue, I wiped the shellac on. I still have three of the guitars I built and I have seen no signs of the finish failing in any way. BTW, Behlen sells it's instrument lacquer in spray cans too. I use that for small parts when I don't have any larger spray jobs to do and it does a decent enough job.

[george wilson]

I do not like Behlen lacquer. Why? Because back in the 60's I was spraying a classical guitar when I noticed that the WHOLE colored wood rosette had melted its color into the lacquer. The whole rosette's "ghost image" was sliding to one side of the guitar. I had to strip the guitar and re do,carefully spraying LIGHT coats over the rosette,or stopping it off with shellac. I can't remember which. I never used Behlen again. Now,it just might be the only lacquer available. I'll Google it.

I never had that happen with Sherwin Williams lacquer. BTW,Martin used Sherwin Williams lacquer at that time.

I don't know if it is available these days,as I bought several gallons wholesale years ago,but Star nitro lacquer is what I use now. It is the PRETTIEST lacquer that I or my guitar making friends have ever seen. I use the "Water White Gloss". They sell an amber tint also,but the water white is my clear lacquer of choice. You might have to buy a 4 gallon case to get it. I bought about 3 or 4 cases. However,the wholesale price,if I recall,was a LOT less than others' retail.


EDIT: LONE STAR INDUSTRIES,INC. seems to be the company that makes tar lacquer. I don't know if they have gotten "too big" to sell a few cases of lacquer to an individual or not. There is a telephone number listed at their site,at least.

Be sure to Google exactly what name I wrote above,or you'll only get listings for cement companies.

[Allan Speers]

I think Stew Mac used to sell Behlen in a spray can, but I see now that they are selling a brand called "Colortone."

http://www.stewmac.com/Materials_and_Supplies/Finishing_Supplies/Finishes_and_Solvents/ColorTone_Aerosol_Guitar_Lacquer.html

Has anyone tried this?

I've also seen a lot of instrument builders rave about this guy's laquer: (spray can and regular)
http://www.reranch.com/products.htm

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FWIW, I do have a nice HVLP setup, but it's so much blooy work to set it up & then clean it, for small projects I never find myself using it.

[Julie Moriarty]

Honestly, Allan, I really can't tell the difference between the two different brands of spray can lacquer I've used, Behlen and MinWax. I used MinWax on the first guitar body I made. I've looked at it many times since and it seems fine. And that guitar gets played a lot, probably a couple hours a day. But it's a solid body and I'm sure whatever lacquer one uses isn't as crucial as for an acoustic.

I chose Behlen Instrument Lacquer because I was finishing an instrument and it was on the shelf at Woodcraft. It seemed like the right thing to do. Having no experience at the time, I believed I was buying a great product. And nothing I saw convinced me otherwise. But I have nothing to compare it to. It's the only lacquer I've used with my HVLP gun. And since Woodcraft also had that in spray cans, I now use that for small guitar finishing projects rather than MinWax.

Regarding the hassle of setting up for HVLP spraying, I know what you're saying. I have to remind myself the HVLP is faster, lays down the product much better, is so easy to use once set up and that I paid something like $800 for the whole system. That's usually enough motivation to get me to take the time to set it up. Once that's done and I'm spraying, I'm happy I set it up.

[george wilson]

I never have had an HVLP spray setup. I wish I did. I recall when I was young,those old Kirby vacuums had a cheap looking spray gun attachment that was an HVLP! Never used one.

Julie,I'm sure the Behlen is fine as long as you aren't spraying over any dyed wood inlay like you find in the rosettes of classical guitars,or in strips down the back. I'd be sure to stop those off with wax free shellac before applying Behlen lacquer. That includes highly colored woods like rosewoods such as you might use for edge bindings. They can bleed too.

It is true that(at least in the 60's),Martin used 20% solids Sherwin Williams lacquer. I met their salesman and he told me about it. I was using the same thing at the time. But,it is SO LESS PRETTY than the water white Star lacquer I use now. I introduced Star to a really good maker in my area years ago. He was astonished at how nice it looked.

[Julie Moriarty]

I never have had an HVLP spray setup.

I've used compressor type sprayers and airless sprayers in the past. Both convinced me I hate sprayers. When I bought my HVLP system I was about to take on a cabinet job for our kitchen. I knew there was no way I could achieve the quality of cabinet shops by brushing. For what they would have charged me, I justified buying the HVLP system. Once I got to know the sprayer, I was hooked. I don't even mind the cleanup.

[Eric L Bashore]

For touchup oversprays I've had great results using Mohawk lacquers. The best for touchup is a product called Perfect Blend. It's a higher solvents/low solid lacquer so it bonds and flows nice. The can also has a special tip that gives good atomization. Konig also makes a touchup lacquer that works really well. With either product expect a little sticker shock. I think a can of Perfect Blend runs about $11, but for it's specialized use I've found it to be worth the price.

As for the run, I would scrape with a razor blade, then sand with 400 on a block and continue spraying. For what it's worth I like to take the corners off of my razor blade before scraping. The last thing you want to do is catch a corner and have a big scratch to fill.

I wouldn't worry about your sheen difference until the very end unless you are going to switch to a different product. Any good repair lacquer will come in a variety of degrees from dead flat to high gloss. I think Mohawk sells 20,40,60, and 80 degree. I usually spray gloss and then adjust the sheen mechanically. Sand and buff to a high gloss like normal, then take the sheen down. My favorite method is to use a Mr. Clean Magic Eraser (used dry). I know that sounds a little strange, but they are just abrasive enough to knock off the gloss and leave an ultra fine scratch pattern.

Hope this all helps.

[george wilson]

If I want a gloss finish,I use only gloss for the entire job(after filling the grain with diluted epoxy. Low gloss lacquers are not as transparent as gloss. They have minute fibers in them to cut down the gloss,but they also cut down on transparency.