One problem that every one comes across periodically is the tightly closed jar that doesn't want to open. There have been a lot of products developed for just this problem, but you don't always have one available when you need it. So you often have to improvise with the materials that you have at hand. One tool that you can use is duct tape. This may seem counter-intuitive since you normally use duct tape to make things stick together and not to un-stick them. But it actually works pretty well. Here is how to do it.
Step 1: Wrap the Duct Tape Around the Lid
Tear off a strip of duct tape that is about one foot long. Line up the bottom of duct tape with the bottom of the lid. Apply the tape and wrap it around the lid at least one quarter of the way around. The more tape that is in contact with the lid, the better it will hold. So if the tape slips you need to wrap it around more of the lid. This may be necessary if you have a very thin lid with a small surface area.