What in the world is going on with my finish?

[GeneK]

Guitar is only about two years old, and the nitro finish is bubbling on both the side and back of the upper bout (low e string side) along the wood grain on both sides of the binding. The instrument has never even been taken outside since I got it (I'm the first owner), it has always been stored in its HSC, temperature has ranged from 68-83, and I have always kept the D'addario two-way packets in it (the humidity doesn't fluctuate much where I live anyway).

Does anyone have any idea what is going on here? I don't even really touch this part of the guitar while I'm playing. Everything was fine up until about two weeks ago.

Back: https://imgur.com/L9xBYSA
Side: https://imgur.com/xg2UJLe
Same as above but without the obnoxious flash: https://imgur.com/DBCKC7N

[B. Howard]

Appears to be some uncured pore filler in those spots causing the finish to check and pop.

[GeneK]

Thanks! Is this a serious issue? Can it be spot repaired or is this something bigger?

[B. Howard]

The possibility exists that this could affect more areas over time.

It can be spot repaired but will likely still show as slightly lighter areas due to the fact the repair must be sanded to bare wood to deal with the failed pore fill material. The original finish, at least the fill is probably UV cured material and I would recommend repairing with the same. This would also help cure any additional uncured filler that hasn't popped yet.

[mirwa]

What brand of Guitar?

Steve

[guitarguitar]

All respect to Brian as he is highly talented in this trade but that is not "pore popping". It is subtle put the finish is bubbling over the purfling and binding, areas not capable of receiving pore fill. Also the affected area is isolated to two small adjacent component locations and not widespread so it is not possible to blame a UV paste fill or other finishing product or method for the bubbles.
The cause for this remains a mystery to me without it in hand but as it's lacquer possibly a localized heat source, or moisture, leaking humipaks. I'd recommend looking into the soundhole towards the area for possible water/moisture tracing.

Skip j.

[GeneK]

Originally Posted by mirwa

What brand of Guitar?

Steve

It is a custom build by Ken Jones (works with the Dream Guitars guys in NC)

Originally Posted by guitarguitar

All respect to Brian as he is highly talented in this trade but that is not "pore popping". It is subtle put the finish is bubbling over the purfling and binding, areas not capable of receiving pore fill. Also the affected area is isolated to two small adjacent component locations and not widespread so it is not possible to blame a UV paste fill or other finishing product or method for the bubbles.
The cause for this remains a mystery to me without it in hand but as it's lacquer possibly a localized heat source, or moisture, leaking humipaks. I'd recommend looking into the soundhole towards the area for possible water/moisture tracing.

Skip j.

There is indeed some bubbling over the purfling too, it looks like.

I'm totally certain it's not moisture, as I store the case flat and if it leaked it would have leaked into the center of the back. But here is an interior photo of the shoulder in question:

https://imgur.com/cBc15p0

As for heat -- I know you'd have to take my word for it, but it was ALWAYS in the case when not being played. I never left it out, not even once.

[mirwa]

Without knowing what the finish is, its a hard guess

Steve

[GeneK]

Originally Posted by mirwa

Without knowing what the finish is, its a hard guess

Steve

It's a nitro finish.

[B. Howard]

Originally Posted by guitarguitar

All respect to Brian as he is highly talented in this trade but that is not "pore popping". It is subtle put the finish is bubbling over the purfling and binding, areas not capable of receiving pore fill. Also the affected area is isolated to two small adjacent component locations and not widespread so it is not possible to blame a UV paste fill or other finishing product or method for the bubbles.
The cause for this remains a mystery to me without it in hand but as it's lacquer possibly a localized heat source, or moisture, leaking humipaks. I'd recommend looking into the soundhole towards the area for possible water/moisture tracing.

Skip j.

Skip, notice the wood bindings? They take pore filler too!

Also obviously you have never scanned a UV filler with a UV wand to cure because if you did you would know just how easy it is to miss little spots just like this if not done evenly.

I highly doubt that this is water damaged nitro. Never seen water do this to nitro ever....

[mirwa]

Originally Posted by B. Howard

Also obviously you have never scanned a UV filler with a UV wand to cure because if you did you would know just how easy it is to miss little spots just like this if not done evenly.

Brian, why do you think it was uv pore filled, totally unusual for a builder to uv pore fill and then paint the guitar in nitro. To my logic of thinking, if I prepped the guitar with uv, I would keep going and do the top coats in uv as well.

I totally agree it looks typical of uv pore filler failure

Steve

[guitarguitar]

This is a really interesting mystery and we can all benefit form learning the cause, especially the OP.

Brian’s supposition as I understand it is localized uncured UV paste fill. Its possible if the luthier used that product. I use a UV3 Spot cure and find it hard to imagine missing a spot like that even with a wand. If the OP can contact the builder to ask what was applied to the substrate that would help. Maple and ebony are not coarse grain and do not have large pores so the chance of uncured uv paste fill causing bubbles over them seems unlikely.

I would ask any of the recent posters here to look at the bubbles in the finish and knowing that is top coated with lacquer answer this.

Have you ever seen this on an instrument before and if so what caused it?

I have, many times and it was from close proximity to a heat source.

I understand that the OP has ruled that out but I’d like to know if anyone has encountered similar bubbles and realized the cause.

Thanks for your participation, lets keep it light and get to the bottom of this.

Skip

[John Arnold]

totally unusual for a builder to uv pore fill and then paint the guitar in nitro.

Collings does.

The only time I have ever had an adhesion problem with nitro is when using oil base paste pore filler. After that fiasco I switched to water based pore filler and had no more issues.

[guitarguitar]

Not completely correct. Collings tried a UV cured paste fill around 2000 and quickly stopped after the paste fill crystallized under the base coats. They switched back to a Naptha based pore fill and continue to this day. Over that on most acoustics (except natural models such as Maple) they apply 2 mils of UV polyester scuffed to 320 and nitro top coats.

[Truckjohn]

I think this is the sort of thing you need to pursue with the builder. Whatever is going on - it appears to be under the nitro..