Repairing a dent in a guitar finish - Luthier Tips du Jour Mailbag
In this episode, luthier Robbie O’Brien shows how to fix a dent in a guitar top using GluBoost products.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Robert O'Brien: Today's Tips du Jour Mailbag question comes to us from Spain. "Robert, I have a ding in the top of my guitar that I would like to fix. Is there a way to do this without refinishing the guitar? Pablo, in Spain."
Pablo, there is a way to do it. With a little bit of experience and the right products, you can make it happen. Now, I've got a guitar that came into my shop just a few days ago with this exact problem. Let me show you how I fix it.
The dent
So Pablo, here's that nasty ding in the guitar top here, and this is a cedar top, so it's a little softer. So yeah, you can see it. Now I can't make the ding go away, I'm not magic. But what I can do is level the ding with the GluBoost products, and let me show you those.
GlueBoost products
So Pablo, here's the line of GluBoost products. There's a super-thin or ultra-thin CA glue, a thin CA glue, and this is what they call Fill N' Finish, which is a little thicker variety. And that's what I'm going to use along with the Accelerator to fix that ding.
Clean the area
So I'm going to start by wiping a little bit of naphtha on the area with a small paper towel. What I'm going to do is try to clean it, degrease it, because who knows what kind of guitar polishes and things have been used over the years, and I want to make sure I get good adhesion with the GluBoost products. So I'm going to just clean the area real quickly.
Apply the finish
So I'm going to start by placing a little bit of the Fill N' Finish into a little yogurt cup top. And I'm going to use a pipette that I got from LMI. Put a little bit in that and then use that to apply it to the ding. Now, ideally, you want to leave it just a little bit proud. So I've got a hump on the top of it here, and then I'll level that. Now it's got to dry. I'm going to use the GluBoost accelerator. You want to back up at least 10, 15 inches from the surface and mist it. And then I'm going to let it dry for a couple of minutes and come in a level.
Scrape level
So here's another little trick for you, take a razor blade like this and some clear cellophane tape. Wrap it around it like this on the edges. What that does is create a low spot in there, and I'm going to use that to scrape over the top. And this will level the GluBoost.
Now, as it cured, it shrunk just a little bit. So I'm going to apply just a little bit more. And once again, I'm going to hit it with some accelerator. Make sure you back up a good 10, 15 inches away.
So now I'm going to come in with my razor blade again, and lightly scrape this thing down until it's flush with the top. I've scraped the majority of it flush with my razor blade.
Sanding
Now I'm going to come in with a hard sanding block and I'm going to start with a higher grid. This is a thousand grit dry, and I'm going to level it just a little bit more right in that area. It's better to start with a higher grit and work your way down, than to start one that's too low and you can't get the scratches out. Happened to a friend of mine one time. So now I'm going to jump it up to 1,200 wet dry, and I'm going to hit it wet. So just a little bit of moisture on there.
So at this point, you can keep using your regular sandpaper and take it all the way up as high as you want to go. Some people take it up to 2,000, 3,000 and then go to a buffing wheel. I'm going to just do it all by hand.
Buffing
What I'm going to use is Micro-Mesh products that I got from LMI, and they're very, very fine pieces of material, kind of like a sandpaper. I'm going to use them wet. I'm going to go through a series of grits here. I'm going to start with the 3,200 grit. I'm going to get it wet, and instead of using the sponge block, I'm going to use a hard block.
[Robert buffs the spot using a back and forth motion]
By the way, this guitar is from Australia. It's from the Australian school. It's a lattice-brace. It's a cedar top, and this top is extremely thin. So if you decide to tackle this, be very, very careful you don't damage the finish or the top. Now, I'm jumping up to 4,000 grit. Now we're going to 6,000 grit. Now we're up to 8,000 grit. And finally, 12,000 grit. That's as high as the Micro-Mesh goes, but it should be getting fairly shiny at this point. There we go. That's as far as I'm going to take it. And I'm going to clean off the moisture.
Polishing
We're already starting to get a nice little shiny area there. Now I'm going to use some polishing products. I'm going to polish that right up to a mirror finish. So now I'm going to use a couple of plastic polishes that I got from LMI. These are Meguiar's products. I'm going to use a clear plastic polish and then a clear plastic cleaner. I'm also going to use a cotton ball so I have something nice and soft. I don't want to put scratches back into the finish. So this has a very, very light abrasive in it. So it's going to remove some of the deeper scratches and then I'll use the polish to go ahead and get it right up to a nice gloss. This is almost good enough the way it is, but I think if I use plastic cleaner, I can get it even better. Better is good.
So now, here I am with the plastic cleaner. And this is going to get right up to that showroom shine. In fact, this area of the guitar is going to look shinier than the rest of it. At this point, I'm trying to go a little bit more with the grain than across the grain. All right, so here's the finished product. Right here is where the ding was, and it looks like we got a lot of the shine back. It's really shiny in this area. The ding is leveled. Of course, you can still see the damage. I'm not a magician. All I'm doing is trying to fix somebody else's screw up, and I think I've done quite a good job. And with the help of the GluBoost product, there it is.
So Pablo, in Spain, thank you very much for your question. I hope you found this information useful. Now, it's going to happen. You're going to get the dings in your guitar. When it does happen, the information that I provide in this video, and along with the GluBoost products, I think you can fix the issue. So, saludos from Parker, Colorado and happy building.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instruction available.]
