Robbie demonstrates a couple of ways to level marquetry rosettes.
Today’s Tips du Jour Mailbag question comes to us from Mexico.
“Robert, I’m having trouble with low spots in the rosette and these usually show up during finishing. Is there a fix for this? Thanks for your videos. – Marcos in Mexico”
Marcos, it’s a very common problem actually. Especially on the classical rosettes. All those tiles, all those little pieces of wood are end grain and very vulnerable to tear out, chip out, what have you, during the installation and sanding process. They also are very thin and that brings up another problem. How much can you sand to get those low spots out – that actually come with the rosettes – without going through it during the installation process? So, there are ways to fix that. Ideally, if you could sand then all out before you even get to your finish work, that would be the way to go. That’s not always possible so let me show you just a few ways to level that rosette during the installation and finishing process.
So Marcos, the first method I’m going to show you is with hide glue. I’ve got my hide glue pot here going and I’ve got a small little mixture of hide glue in this little plastic bottle here. These little plastic bottles work great for mixing up small amounts of hide glue and you can just use them as a glue application bottle. And they work really well.
So I’ve got my hide glue mixed up. It’s a little on the watered-down side. It doesn’t have to be adhesive quality but just enough so you can penetrate the end grain here and level those low areas. Now, like I said, ideally you want to sand all of that out. This rosette is extremely thin. It gave me a little bit of trouble during the installation. I’ve got some low spots there that I probably could sand them out. However, I don’t know. I’m a sissy today and I don’t want to run the risk of going through there. So I’m going to level it with hide glue. I usually use this method if I know that I’ve got these low areas before I get to finish work. So here we go – take my hide glue and just put some on the rosette and it will level itself because it’s very liquid. Very, very thin viscosity. You could also use fish glue for this and you wouldn’t have to cook it. However, I would probably water it down just a little bit. Now I’m going to use my brush here just to kind of level this. And it’s just now beginning to gel. So put it on there just a little bit heavy and it will come in and go into those low areas and do the leveling for you.
Once it dries, then you can just sand it and, voila. You’ve got a level rosette. Problem solved.
The next method I’m going to show you is using CA glue or cyanoacrylate glue. Thin viscosity, water-thin, and a small pipette to apply it. Now this rosette has already been installed, the guitar’s been built, and I started putting on some wash coats of shellac and I noticed that there are a couple of little low areas down here. Small little chip-outs. And so I want to go ahead and level those before I get farther along in the finishing process.
So I’m going to start just by lightly sanding that area. This way, the low area is not quite so slick and the glue has something to adhere to. Now I’m going to take my pipette and just put a couple of drops in those low areas. Just a couple of low areas there and just a little drop is all it takes. What you don’t want to do is use accelerator at this point because the accelerator – all it’s going to do is dry it too quickly. Perhaps you get some air bubbles in your CA glue and little white marks around the edges of the CA glue. So just put a little drop in there like that and that should do it. Let it dry over time, it just takes a few minutes. Don’t use the accelerator to cure this.
Marcos, here’s another method – the third and final method for your bag of tricks. This rosette has quite a few low areas. It was extremely thin and when I sanded my top, I didn’t want to go through it, once again. So I’m going to use a water-based pore filler called Aqua Coat. I got this from LMI. It works great for leveling low areas and you can do it after you’ve already sealed the wood. Also, that CA method, you want to make sure your top has already been sealed so you don’t run the risk of getting CA glue wicking into the end of the Cedar or Spruce or whatever top you’re working with. So this is a great candidate, as well as the CA method, for rosettes that you’ve already begun the finishing process and then you notice a low area.
So, once again, I want to give it a little bit of bite so I’m going to come in and just lightly sand the rosette area. Any of the small little divots of low area need to be sanded so this has something to grab onto. So if you decided to use your finish to level these areas – if you’re using a high solids product like a lacquer or even a urethane, polyester – eventually you would get them all filled, however, you would probably have a little shrink back over time. So I like to use a leveling agent. In this case, I’m using the water-based pore filler made by Aqua Coat.
Now that I’ve got that thoroughly sanded, I’m going to come in and spread some pore filler on there and level those low spots. So to apply the Aqua Coat I’m just going to use a paper towel. Take a little bit, put it on the towel, and just rub it in. I want to leave a little bit of buildup on there and then I’ll sand it down level to the top. If you happen to get any out in the areas that you don’t want, just wipe it right off because the top has already been sealed with some seal coats of shellac. In this case, this will be a French polish. So we can just go ahead and wipe that off. Now that I’ve got that pore filler in the voids, I’ll let that dry. It dries very quickly because it’s a water-based product. Then I’ll come in and lightly sand. If I need to I’ll apply another coat but that should solve your problem.
So Marcos in Mexico, thank you very much for your question. As you’ve discovered, having a level rosette under a finish is very important to achieve that nice level finish. Especially during a high gloss finish. With these three methods that I’ve given you, I’m sure you’ll have no problem achieving that high gloss level finish. Happy building.