Candling a Top

I read about doing this in a guitar building book and it is called "candling". It is like an x-ray of the top using 500 watt shop light. The top here is sitka spruce leveled to about 110 (0.110 inches). It is a single piece and not bookmatched. It was graded by the supplier as "3AAA+ WCU". Not sure what WCU means. Several interesting things can be now seen which were not apparent before it was sanded down.

Note the lateral density on the lower left petering out and then the strong vertical density on the right. Very asymetrical and the densities are quite different across the top. I think in a guitar top this might be disastrous, but in a ukulele, who knows, it might actually be interesting.

What do you experienced builders think?

I think candleing the plates refers to checking the joint line on a bookmarked top or back, with a.candle in the back.

Sure there is that. To see how good your joint is, but this is about a million candle watts to see what is going on actually inside the wood. I think it is kinda cool.... Beautiful even.

If you carve a top, for a violin or an arch top guitar, candling reveals thick spots and uneven areas.

If it IS stiffer in that darker area, i'd just sand it a little thinner.

Personally, I wouldn't use one piece tops, unless it looked the same across the board. I'd rather a 6 piece top jointed invisibly then a one piece top with grain variance. Of course, they both might sound the same