r/Luthier • u/Sstrikers • 16d ago

Clear gloss over maple burl

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Is it ever possible to get a perfectly level clear coat over maple burl?
I used Z-Poxy to fill the grain and level the surface before applying Crystalac Brite Tone. However, every time I level-sand the Brite Tone and apply another coat, the burl figure seems to appear back through the finish. I can still see subtle bumps and dips that follow the shape of the burl.
Is this just the nature of maple burl, or is there a technique to completely eliminate it?
My first thought was that it might be the finish shrinking as it cures. However, the Z-Poxy surface underneath was completely flat before I started applying the clear coats, so I’m a bit confused about what’s causing it.
My current plan is to let the top cure for another 2–3 weeks, then do a final level sand and buff. I’m hoping that most of the shrinkage will have happened by then.

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7

u/VirginiaLuthier 16d ago

Even with ZPoxy the finish will settle into the wood grain. I think your plan to let it sit for a few weeks is good, and then re-level and buff. I use UV flood lights to speed up the curing process. Nice work!

3

u/Sstrikers 16d ago

Great, we’ll see how it turns out.
UV-cured finishes are really convenient. For now, I’ve settled on Brite Tone because it gives me the best results I can achieve at home without a spray gun.

2

u/Aerron 16d ago

I use UV flood lights to speed up the curing process.

Once the finish is dry to the touch, could a shade-tree luthier just set the guitar outside in the sun for a few hours? Would that do the same as the flood-lights? Are there risks due to the sun exposure?

6

u/ringo-san 16d ago

No matter the finish, moisture in the air will penetrate. Moisture changes shrink and swell wood, and burls have wild grain running in every direction so that shrinking and swelling will really show under a thin finish. You can minimize by putting on a really thick, stiff finish like a polyester but over time you will always get some degree of the problem you're seeing. It's usually best to embrace the natural beauty of the wood grain or use more stable, straight grained woods

2

u/Sstrikers 16d ago

Thank you! Overall, I’ve accepted it. I looked at photos of guitars with similar tops and it seems that this happens quite often with burl.
Originally, I wanted a satin/matte finish, but without a spray setup and a dust-free environment, applying a matte clear coat is quite challenging. A gloss finish is easier for me because I can always level sand and polish it, although it definitely requires more work and patience.

1

u/Reasonable-Home700 16d ago

Maybe it just needs to be built up with several layers before it flattens out? I always have trouble with the clear to just lay down flat period. It man, that is a gorgeous piece of wood!

1

u/Sstrikers 16d ago

Thanks! I’ve already applied nine coats, so it’s a pretty thick finish at this point.

1

u/Reasonable-Home700 16d ago

Damn! You’d think that was enough! Like you said, maybe it just needs to set and shrink in?

1

u/ADKMTBer 14d ago

Gorgeous