Our firm buys window envelopes by the 500 box. Some boxes have had poor glue quality. When sealing the envelope we need to press it down for several seconds to make the seal stick. This causes extra time to be needed on our mailings. Other times the glue is great and we breeze along one swipe with a damp sponge and one swipe to press and seal. We always buy at Staples and would like to see better quality control.
I thought they were self-stick. I bought these as an emergency and I dislike them intensely. I need to lick them or wet them. I haven't done that in years.
Overall the envelopes are great they secure well and are the perfect fit for all my documents. Sometimes I do find a couple of the envelopes that are loose and the folds from the back of them are secured and have to be re-glued along with the closing flap.