This catalog from the historic glass factory Cristalerías Planell (Barcelona), belongs to the Municipal Archive of Barcelona, Les Corts District, and it had BluTack on its front cardboard.
In few months the adhesive provoked fat stains, fibres oxidation… and favored tears formation. Wanting to take off the cover from the support where it was fixed (a wall), the broken result was the cardboard, not the wall (logical). So this supposedly non-greasy and reversible Bluetack is neither one thing nor the other: don’t let be fooled!
The manufacturer states that its use is suitable for non-porous surfaces, from which it is deduced (since not specified) that paper would be excluded from the ideal media where to use Blu Tack.
The intervention consisted on taking off the blue mass and removing the fatty remnant (the stain) using non polar solvents. After that the tear was inserted with 3 gr japanese paper on the front, and also inserted with a thicker paper on the back.
It could be satisfactory restored… but mistrust BluTack to avoid scares!