There are a number of tried and true ways to seal your envelopes. Here are some of our favorites: Water + QTip: Grab a cup of water, dip your QTip in and use it to apply a conservative amount to the glue line of your envelope. Make sure to press firmly until the adhesive holds. Pros: Firm hold. Cons: Risk of moisture effecting the cards inside. Takes a bit of time to hold until sealed/dried. Glue Stick: Use a strong-hold glue stick and glide along the glue line of your envelope. Again, make sure to press and hold until the glue sticks. Pros: No moisture risk. Cons: Lengthy process due to the need to hold and press until the glue dries/sticks. Envelope Moistener: Grab a bottle of your favorite envelope moistener and apply to the glue line. Be conservative! This glue tends to spread quickly and you don't want any adhesive to get inside the envelope and compromise the cards inside. Pros: Quick application. Cons: The glue is a little messy and can damage your cards if you're not careful. Double-Sided Adhesive Tape *our favorite*: Use a double-sided adhesive tape and an ATG tape gun. Run along the envelope glue line, press firmly and voila! Envelope sealed! This is our preferred method and what we use when performing mailing services. Pros: Fastest method with strongest hold - no worries about your envelope opening in transit. Cons: It is the strongest hold so there can be damage to your envelopes when guests open. We recommend using an inner envelope if you will have a decorative envelope liner to ensure guests don't rip right through and miss it.