In my quest to reclaim a Mason jar (specifically Classico pasta sauce jars) I needed to soak off the labels. I submerged the jars in hot water and let them sit until the paper was easy to pull off.
The best part with the Classico jars is that the glue they use is also water soluble! I was able to remove the glue with hot soapy water.
With another jar, I removed the glue with Goo Gone and a paper towel. I was amazed at how well this worked!
I love vinegar and use it for everything, I have a spray bottle full. To remove a label, I simply wet the label good then I spray with vinegar.
