Used it on surface level squeeze out and stripping old glue surfaces for furniture restorations. Works great (but slow) and it softens Titebond original and Titebond II very well. The only rub is having to keep it damp by re-applying with a small sponge because it dries before the glue softens. I prepared a small amount of dissolved baking soda in water and scrubbed the areas treated with the DeGlue. Followed with a water soaked sponge. These 2 steps are probably not necessary but I was worried about the longterm effects of Acetyl acid on the wood surface. If you haven't bought it yet I would suggest using regular white vinegar (Acetyl acid) applied with a sponge on a test piece and see if it works to your satisfaction.
I need to learn to wait until the coffee kicks in before I post. Acetic acid is the active part of the DeGlue stuff and vinegar. A mind is a terrible thing.
I have used this stuff on and off for a few years to remove dried hide glue. It is somewhere between a liquid and gel in viscosity and stays put better than water. I have used it in situations were I was concerned that warm water and/or steam would raise grain more than I would like.
It did the job well but there was one drawback; since it is basically vinegar it can occasionally cause stains to appear on some woods via chemical reaction. Actually, it may not be just a reaction to the wood but a reaction to metallic residue from abrasives, etc.
I have not had the staining problem on spruce but on some of the hardwoods I use in dulcimers it has been an issue so I mention it just as a warning about another possible adventure in lutherie.