Sugru is always a little firmer when used straight from the fridge. Which is the best place to store it if you wish to prolong its shelf life. Some people let it rest for about 5 minutes after opening the pack; this helps to reduce the stickiness.Click to see full answer. Also, what does sugru not stick to?Like most adhesives, Sugru struggles to bond to plastics with certain oily finishes such as polypropylene, polyethylene and Teflon™, some powder-coated metals, and chalky or dusty surfaces. For best results with all other materials, ensure the surfaces are clean and dry.Also Know, how long does sugru take to harden? 24 hours Also, can you use expired sugru? Shelf Life Unopened Sugru will stay fresh for 13 months from the date it is made. If you use it within this date, the cured Sugru will last and last. You’ll find a Use-By date on the back of each single-use pack.Is sugru permanent?Sugru sticks permanently to lots of stuff like ceramics, glass, metal, wood, rubber, and most plastics and fabrics. It doesn’t leave any residue on the Sugru, and is very clean and easy to use.