Luthier Tips du Jour Mailbag - Buffing High Gloss Finishes

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In this episode, Robbie O’Brien answers a viewer’s question about buffing high gloss finishes.

Video Transcription

[on-screen text reads: Luthier Tips du Jour Mailbag]

Mailbag question: I'm having trouble getting scratches out of a high gloss finish, can you offer some advice?

Robert O'Brien: Today's Tips Du Jour Mailbag question comes from a viewer in Mexico. "Dear Robert, I'm working on a high gloss finish for my guitar, and I'm having trouble getting all the scratches out of the finish. Can you offer some advice? Diego in Mexico."

Things to consider when doing a high gloss finish

Well, Diego, first of all, congratulations for trying to do a high gloss finish. This is one of the toughest finishes to achieve with perfection. In general, the higher the gloss, the more those imperfections like to show up.

Here are some things to consider when doing a high gloss finish.

Spray technique

First of all, your spray technique has to be very good. The better you can lay down that finish, the less sanding you have to do later to get it level. This not only saves you time, but you're putting fewer scratches in as well. You also don't run the risk of going through the finish and depending on what type of product you're using, if you go through the layers, you have shadow lines or witness lines.

Using the right sandpaper

The next thing to consider is your sandpaper that you're using to level the finish. Not all sandpapers are created equal. I prefer the industrial grade. I also use wet dry paper when leveling my finishes. Not all sandpapers are created equal also when it comes to the grit. For example, there are two grading systems when it comes to grit. First, there's the North American CAMI grade, and the second is the European P Grade. Now in your lower grits, 150, 220, up to about 320, they're pretty equal. Once you start getting above 320, the European grade is different than the CAMI grade so if you have two different types of sandpaper, and they usually sell both types and everywhere around the world that I've been, you can get yourself in trouble by mixing and matching the different grades of the grit. For example, in the P grade, once you get above 400, you're getting 500, 600 grit, it's equivalent to about half that in the North American CAMI grade, so be careful with that. It's possible to put scratches back into your finish.

Buffing wheel

Another thing to consider is your buffing wheel. Now, I have dedicated buffing wheels for each grit of compound that I use to polish out the finish. I usually wet sand my finishes up to about a thousand grit. Now that's the North American CAMI grade. Then I go to the buffing wheel and I start with the coarse compound. I progress through all the way up to the extra fine compound. By the time I'm into the mid-range of the compounds, I'm usually starting to get a very high gloss on my finishes. The final grits are just to get that extra shine, the high gloss mirror finish, where you have to use sunglasses in your shop. If not, you're blinded by the shine. That's the goal.

As you're buffing on your buffing wheel, if you place the guitar, if you look at the finish through the old-fashioned, I call them old-fashioned, but they're harder and harder to get these days, is the incandescent light bulbs rather than your fluorescent or your green light bulbs, let's say. If you look at it under the incandescent light bulbs, you can see the scratch pattern much better. You can also take it outside, and natural sunlight will show that scratch pattern a little better as well. And you'll be able to see when all those scratches finally go away.

Diego, I hope this information helps. Like I said, the high gloss finish is very difficult to execute with perfection so my hat's off to you. Good luck and happy finishing.

StewMac

 

Robbie O'Brien

Luthier and Instructor, Lutherie Academy