Acoustic Guitar Construction

I have built this crossover guitar. It sat in the house for 4 weeks while we were in India. When we left a month ago the humidity in the house was probably around 4o to 45%. It is now around 55%.

The top is fan braced (9) but has no bridge patch. I'm pretty sure the top was okay when we first got home a week ago. The guitar was out until last Tuesday when my wife put it in a case. I took it out yesterday to set the bridge location, and I found the top caved in as in the picture I've drawn. It is still domed on the edges, but down the middle it has sunk in, probably around 1/8". My first thought was, this thing has dried out, but then the humidity is higher then when I built the guitar, so does that mean that this action of the top is due to too HIGH a humidity? I don't know which direction to go with it so for those of you guys who can tell me what is going on I'd sure appreciate the help. Thanks.



Kevin

Jee Kevin, I have no idea. Was the top domed (not doomed) in the first place or flat?
If it was concave at first it could get more concave while wetting.
I hope others have better thoughts.
Herman

I've seen this happen to classic sound boards that were braced in a dish or solera, the main reason I glue on a flat surface. I think its the moisture in the glue having an affect on the plate. You mentioned that you "took it out" from where? Could be an equilibrium problem where there is more moisture on the inside of the guitar than in the room. Blow dry the inside a little and see what happens. $.02

A fan brace classical guitar that does not have the bridge glued on has no lateral bracing in the lower bout. So it does not take much to have it go slightly concave or convex with humidity changes. My suggestion is to glue on the bridge, either flat or with a slight radius. The bridge and ultimately the string tension will pull the top back up.

If the top expands (from adding moisture) it has only two directions it can go: up or down. Looks like yours went down.

Both John and Ken make good suggestions. Let us hope this works out for you. I bet it will.

Thanks guys, it is encouraging to hear your responses. I kind of panicked. The only thing that made sense to me was higher humidity has caused this so I will go with that and see if I can restore it with a little help as Ken suggests, then store it in the case and see if I can dehumidify it some.
I am pretty sure that I will French polish this guitar.
John, I thought about the fact that the bridge needs to be on there to support that top in this area. If I glue the bridge on now will I have difficulty getting the shellac finish nice and level around the bridge? Anyone done it this way?

Brian Burns does it that way, you might drop him a line and ask him how he does it.