Materials are anything that a product is made of, or the product itself.
A good glue you can use for soft plastic which is a flexible material is Gorilla Glue.
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Depends on which glue. -Try Goof-Off first.
Tape is the binding that glue can be applied to. Glue is a sticky stuff that joins to peices of material together.
glue
It's a different material for almost every glue, but it's known as the 'carrier'.
Generally you would use an epoxy or a form of the brand Gorilla Glue. Normally it depends on the other material.
Silicone is best for that.
pva
use glue
No, glue sticks used with a glue gun are not waterproof. They are typically made from thermoplastic adhesive material that can soften or dissolve when exposed to water or moisture.
The best ways to put gems on a material is to use a hot glue gun, super glue, or an iron. (heat would be the best bet because it adheres/sticks to the material better).