Is this a crack start?

[groove87]

On spruce guitar tops with a nitrocellulose finish, the wood grain often stands out, creating a 3D effect (like waves). I’ve noticed this phenomenon on all my guitars as long as the finish is less than 3mm thick. On my L5, there is one area where the same phenomenon occurs, but one grain stands out more than the others. Is this normal, or is it a sign of a future crack in the wood? Upon close inspection (using a magnifying glass) or looking inside with a mirror, I don’t see any signs of an impending crack. Any advice?
Thank's for your help

[Jimmy blue note]

Hard to tell from the photo, the reflection makes the finish and grain difficult to see. I will say that's a particularly vulnerable area because it's end grain and an area where the bridge exerts a strong downward force on the F hole area where the grain integrity is broken by design.
So I won't venture to guess or even share my opinion at this point. I will say watch this around the first week you turn your house heat on. As seasons change, cracks reveal themselves and they open up. Have an appointment with your luthier handy and have it cleated ASAP if anything becomes visible from below. Do it then to prevent any potential cracks from spreading as the winter progresses.
If you can't see any evidence of a crack from below, the top would appear to be intact. Keep an eye on it and play as much as you can. Enjoy your guitar! Good luck

[deacon Mark]

It does not look like it to me and is an easy place to keep and eye on. Just put you finger under the f hole to check. Some luthiers are known to reinforce the area around the f holes with very small cleat on top and bottom of the f hole. Frankly builders need to take this into consideration when carving tops. Tops need to be stable and strong and yet not at expense of sound. If this is an L5ces then small cleats have no effect on the sound.

[Jimmy blue note]

It does not look like it to me and is an easy place to keep and eye on. Just put you finger under the f hole to check. Some luthiers are known to reinforce the area around the f holes with very small cleat on top and bottom of the f hole. Frankly builders need to take this into consideration when carving tops. Tops need to be stable and strong and yet not at expense of sound. If this is an L5ces then small cleats have no effect on the sound.

+1 on this sentiment. I do it as a matter of course on my builds. A fitted cross grain strip ln the F hole and pickup cuts. It just makes sense in this very vulnerable part of the soft wood top. Great point deacon Mark!

[groove87]

If I take pics without reflection, we see nothing. I only see this with reflection.
I Will watch if it change.
thank's for your time.
And yes it's a L5 WES...and love it, so I make checks

[Archie]

I had a Guild AA and there was a raised grain line like this. I checked inside but could see no visible crack line. I had suspected that the top had cracked in the carving phase and they glued it back together; but I could not see any real signs of a rejoined surface.
The other thing was that the on the other side of the book matched opposing plate, there was also a slightly raised line in the same position.

Although I’ve not seen it before, I put it down to a raised grain issue that wasn’t rubbed back in the finishing process.

I’m not saying that is what’s happening here but looks similar. Check the opposite of the top in the same area, to see if you have a mirrored effect.
Mine was in an almost identical position to yours.

[Ol' Fret]

[QUOTE=groove87;1355823]On spruce guitar tops with a nitrocellulose finish, the wood grain often stands out, creating a 3D effect (like waves). I’ve noticed this phenomenon on all my guitars as long as the finish is less than 3mm thick... /QUOTE]

I'm sorry - I don't get it!
Spruce consists of softer early wood (some say 'summer wood') and harder late wood (or 'winter wood' - the dark grain lines). In guitar making, before the lacquering procedure, the wooden surface is sanded smooth, like a baby's bottom.No wood grain is "standing out", no visible or palpable waves or ripples exist. The old guys achieved this by "whiskering", applying repeatedly hot water to raise the still existing woodfibers and then sanding. Modern quality sanding papers are sharp enough so that applying water is not longer necessary - we like the wood to be dry before applying the finish.

When spraying lacquer coats on such a leveled spruce surface, a (temporary) phenomenon happens that the pro varnishers certainly could better explain than me: rippling is building up with the early wood being the "valleys" and the late wood the "peaks". That happens the more if you apply thick coats. It also gets worse if you spray the coats too fast (with the result that underlying coats can only dry slowly, while the fresh coats dry faster).
To some extent most lacquers and varnish show this effect, but Nitrocellulose lacquer is especially known for that effect; it is dope with a high shrinking and tensioning properties. Please, don't get me wrong, we all know that we can get a fine finish with nitrocellulose lacquer as well, just by following the proven rules: applying multiple thin layers, respecting the correct interim periods, the time essential for the drying of one lacquering session (one or several layers). This way any rippling or wood grain "raising", which de facto is a sinking of the layers above the early wood, could be avoided.
Well, time is money ... the production rate in factories has always been accelerated.

I can see no crack development on the foto of your guitar, but any judgement would be dubious.

No idea what you mean by "less than 3mm thick" - that would be a shocking lacquer thickness on a guitar, completely self-defeating.


Note 1:
On really old spruce we often experience the rippling effect between early and late wood fibers. In contrast to actual guitar making, in violin making it is sometimes frowned upon to create a super-natural or artificially-looking smooth wood surface; some of these makers still only use scrapers, no sanding desired ... "Texture" is the magic word; it can include some fine rippling and is considered to be a sign of quality of high-quality handcraft. However, it is hardly ever generated by varnishing or lacquering.
Personally, I wouldn't mind about having some degree of spruce (or figured maple) texture, as long as it would not be the result of a hasty or wrong finishing procedure.

Note 2:
Just realized that you might think of the fine figure that some quartered spruce do show, the "silk" between the grain lines. Well, that has nothing to do with the development of crack lines.

[Max405]

Ole fret, amazing bit of information sir.
Thanks, JD

[groove87]

[
Note 2:
Just realized that you might think of the fine figure that some quartered spruce do show, the "silk" between the grain lines. Well, that has nothing to do with the development of crack lines.

It's exactly that.
the "silk" between the grain lines ar generally regular and multiple. It's the first time I see a lonely silk on a zone where other silks ar very thin.

Thank's at the communauty for your advice and help

ps:

No idea what you mean by "less than 3mm thick" - that would be a shocking lacquer thickness on a guitar, completely self-defeating.

it's a joke for low quality guitar with a very thick finish. My 100$ guitar when I start playing has such finish....long time ago

[RJVB]

Note 1:
On really old spruce we often experience the rippling effect between early and late wood fibers. In contrast to actual guitar making, in violin making it is sometimes frowned upon to create a super-natural or artificially-looking smooth wood surface; some of these makers still only use scrapers, no sanding desired ... "Texture" is the magic word; it can include some fine rippling and is considered to be a sign of quality of high-quality handcraft. However, it is hardly ever generated by varnishing or lacquering.

Indeed, my master violin had that, clearly visible in detailed shots thanks to not being perfectly clean:






I'm not certain if this is a result of having been scraped and not sanded; not all instruments from this builder show the same "corduroy" effect.
Either way, wood being what it is it is not surprising that this effect can be much stronger in a particular location than in others, and give the impression that it might be a crack. My classical has a few lines like that that look like a repaired crack without the 3D effect, but aren't. Gently tapping around the area and looking inside confirms what and should in your case too.

BTW, 3mm thick finish?! The top of my classical is barely that thick, so I hope it was a typo?!