Envelope glue

I've been making a few envelopes recently, mainly where I've made a card and I've not had an envelope to match (or the cards quite 3D and I've needed a deeper envelope). When I've made envelopes for myself I've used either glue, a tape runner or double sided tape, however when making cards for others I want them to look professional. 

I was looking at getting some envelope glue and was advised you can make it yourself with gelatine, I brought gelatine (6 or 7 months ago) and just haven't got round to making it. While buying some craft items recently I saw the envelope glue so decided to finally give in and buy some. 

I made my envelope on my Crafts Companion Ultimate Pro. 

I used Collall tacky glue for the three permanent flaps. 

I then went to use the envelope glue and it wouldn't come out and saw it said to push it down, I did this but kind of too hard....

I spreaded it out, however due to the moisture from the glue puddle it made the envelope a bit wet and crinkly 

Once dry, I licked it (it tasted fine by the way) to remoisen and stick the envelope flap down.

It held well however the edges did curl up a bit so I think I need to practice a bit more.