An envelope flap is the part of an envelope that is folded over to seal the contents within, so it is not able to fall out the envelope throughout the postal journey. There are a variety of different flap types that are available, and they can be customised and bespoke to meet the needs of your project.
The most common envelope flaps are:
There are 3 main considerations that should be made when choosing an envelope flap: security and strength, aesthetics, and insertion.
Security & Strength
The flaps job is to secure the contents within, and so making sure that the strength of it is fit for purpose is essential. For example, if the content within the envelope is heavy and needs extra protection, you will need a larger flap depth on the envelope so that it is not going to break open.
There are many different styles that you can consider, with certain styles being associated with certain content within. For example, a Baronial/ Pointed Flap Envelope is commonly associated with greeting cards as it is more traditional, whereas a straight or commercial flap would be generally associated with business letters.
Not all envelope flaps are practical when it comes to using machines that put inserts within the envelope, and so it is important to check with the machine you are using before you choose your envelope flap.