Bought the 3M photo mount the red can as suggested by CHJ and JJ1 thanks again. Bought 2 cans as wasn't sure how far it goes did 7 posters and still seems at least half full. expensive stuff but good 20 euro a can.
I mounted the posters on 6mm MDF for the smaller ones I cut them first on my table saw to size with a 30 degree bevel then spray painted the edge black and attached the poster.
for the larger ones I just stuck them down to the mdf then used my track saw to cut to the edge of the poster. turned them upside down on a piece of scrap and sprayed the edges black with a spray can. If i was two slow Heavy handed when spraying it could bleed under the poster but I quickly learn't that lesson and applied the paint in 2 light spray coats to make sure I didn't miss any spots.
I followed this guys method and it worked very well
https://www.youtube.com/watch?v=v3J8yph1wX8 . My shop was a bit too dusty for perfect results got a few bits of dust under the poster what leaves a tiny dimple but they look way cooler than just normally mounting a poster on the wall. My friends were well impressed. I attached a french cleat on the back for easy mounting to the wall for this I used trusty Mitre Bond.
my friends are all mounted and i Still have to put the french cleat on mine isn't that always the way.
will definitely do it again in the future makes really nice art out of cheap posters.
hope this helps anybody else who is thinking of doing it.
Regards Richard