According to an old CIA manual, the tool should have a smooth edge, preferably with a curved, blunt tip. [2] X Research source These tools can be made by filing down a piece of wood or an ivory piano key blank, but any flat tool with the shape described should work.
If you have opened the envelope partway, you can fold a piece of blotting paper and stick it under the flap to absorb any excess water. [3] X Research source
Never apply water to an area with ink or a stamp over it. Some types of envelope adhesive are not water-soluble. If you notice no results at all, try the cutting method instead. If you notice minor results but not enough to get the envelope open, try steaming.
Whichever method you choose, the flap can be sealed again using tiny dabs of glue, spread over the flap with a toothpick. Some envelopes will become sticky again when the glue is slightly dampened.
If the envelope ink looks wet or starts to run, remove from the steam and try another method.
A smooth, continuous motion is less likely to leave wrinkles, but involves a higher risk of damage if you are not experienced at this task.
Wear an oven mitt to protect your hands. If your kettle doesn’t produce a focused jet, stick a spoon or other heat-safe object into the spout to narrow the opening.
