Best glue for wenge

What glue will be the most invisible for gluing bindings and back

If your joins are tight there is no need for invisible glues. You shouldn't be seeing glue invisible or not... I use CA glue for bindings and Titebond I for gluing backs and tops.

I use LMI's instrument maker's glue for nearly all wood-to-wood joints on instruments. It's similar to many other PVA wood glues but has some slight advantages (it dries hard enough to sand cleanly, it doesn't creep, and it has UV dye in it so you can use a blacklight to check for squeeze out or glue contamination on surfaces before finishing). I've glued wenge with it many times (as well as many other dark woods - walnut, ebony, ziricote, katalox, rosewood, etc) and it has turned out fine.

That said I do have a few friends who keep a bottle of Titebond II Dark around for gluing darker woods to ensure that any slight glue lines aren't visible. It's basically plain Titebond II but it has a dark brown dye in it so it looks about the color of coffee when it dries. There are some places where light colored glue can make an appearance on dark woods, if you're not careful, i.e. at the feathered edge of a scarf on a headstock. but I wouldn't think backs/sides or binding would fall into those categories, so if those are the joints you're concerned about, I would just use whatever wood glue you're using now.

This Titebond Translucent works well for bindings but regular Titebond doesn't seem to be a problem showing glue lines with Wenge either.

Thank you very much for the information