What should you do for deformation of the silicone mold ?

It should deal apart according to the size of the products, In principle, the hardness of the silicone should be according to the size of the products. If the products features small size and detailed patterns on it, the soft silicone can be applicable which the shore A should be 15-20 for easy demoulding and not damage of the patterns. Other wise harder silicone should be needed for large size products, such as products with size 1meter will need harder silicone with 35-40 shore A , then no-deformation. If Large products but features detailed patterns then 30 shore A silicone will be  workable.(The process should be a layer silicone add a layer fiber glass or cloth..).The outer of mold can be plaster, glass fiber reinforced plastic(unsaturated resin and fiber glass) to protect the products from deformation.