Check the manufacturer’s date on the body of the guitar. If the date that appears there is earlier than 1960, it is likely the guitar was constructed with a hide glue. If the date is earlier, chances are the guitar was built using a yellow epoxy glue.
Look for an indication as to where the guitar was built. If the guitar was an inexpensive, imported instrument, a cheap, quick-drying glue like superglue was likely used to put the instrument together. If you can’t find any indication as to the year the guitar was made or the location where it was made, examine the glue.
Carefully examine the area that needs repair or any other area where the glue is visible. You might need to pry back the loose component to gain access to the glue underneath so you can see it.
Examine the color of the glue once you have located it. The color is the easiest way to tell what kind of glue was used. If the glue is a dark color like amber or molasses brown, this is a sure sign that the glue used was a hide glue. If the dried glue is yellow or white, this is a good indication that the glue used was a modern resin glue.