The oldest form to close envelopes knows everyone. The edge of the closing flap is provided with gum, which must be moistened, making the flap sticky to close the envelope.
This closure is also suitable for closing without sticking.
A “striplock” closure on envelopes is a self-adhesive closure.
The adhesive sticking layer on the seal of the envelope is permanent. By removing the strip of silicone paper, the envelope can then be closed.
A4 paper without folding.
A4 paper folded 1x.
A4 paper folded 3x.