Patent ID: 8163115

Claim:
A method for producing an envelope having improved seal integrity, the envelope having a flap and a body portion between which a seal is formed, the envelope including a sealant material disposed along the flap of the envelope, the method comprising the steps of: applying a first material to the flap of the envelope in an area corresponding to the seal location between the flap and the body portion of the envelope; applying a second material to the body portion of the envelope in an area corresponding to the seal location between the body portion and flap of the envelope, the second material including a cobalt chloride solution which changes color in the presence of an aqueous liquid; applying an aqueous liquid along the flap to moisten the sealant material; sealing the envelope by closing the flap onto the body portion of the envelope to form a sealing interface and combining the first and second materials along the sealing interface; visually inspecting the sealing interface to determine whether the combined materials exhibit a change in color to confirm that a seal has been formed between the flap and body portion of the envelope.