Bind a back with its pages without stains I started doing some perfect binding tests. I'm using a vinyl glue. Gluing the pages together worked fine so far.
I'm having some trouble however in binding the cover with the pages. The binding is pretty successful, but because the glue passes through a bit, the paper gets wet again, and the ink printed on the cover dissolves and leaves some stains.
Could anyone give suggestions on how to mix up the vinyl glue or tell me if there are tricks to prevent the glue dissolving the ink on the other side? Sadly the ink is water-soluble and I can't avoid that.
Some pictures will better show what I'm getting at:

The cover before being bound with the block of pages.


The back of the finished bind with stains of dissolved ink.


Stains and wrinkles appears on the cover of this small book.


Close up of the final bind with the pages and cover.
Most likely, the stains appear because the glue diffuses into the paper - the paper being porous, or the glue too strong / dissolving. Try a different paper / glue combination.
About the wrinkles: I guess that you make the binding manually - as in using the bare hands, without any kind of presses, clamps, etc. Use the proper tools, practice using those tools until you understand all their secrets, and then go ahead doing the beautiful work.