Being a permanently ductile adhesive, Bostik Blu Tack never hardens, which means it can be used again and again in order to affix objects onto non-porous substrates (metal, glass, vinyl wallpaper, varnished surfaces, etc.). Blu Tack is used to hang paper (posters, notes, etc.) onto vertical surfaces, for temporary affixing of small pieces to hold them in place while working on them (e.g. when painting or soldering parts of a model), in order to prevent telephones, vases, figurines, etc. from sliding or shifting or for securing things like cables, screws or keys in place.
Bostik should not be used on porous surfaces like painted wallpaper, unpolished natural stone, textile or silk wallpaper because after it has been used as a glue for a long time its oils will tend to migrate.
In order to affix an object with Blu Tack you simply tear a piece of it from the strip, roll it into a ball, place it between the objects to be adhered and press. If you want to undo your bond, you must carefully remove the adhesive from the surface by means of rolling it like a sausage. Any residue can be then removed by employing a clump of Blu Tack itself for dabbing and swabbing purposes.