The selected stone island red protective agent must have good protective effect, and the possible protective and decorative effects due to different surface conditions of stone island red should also be considered. When choosing due to an important principle, it is no matter use what grade of protective agent, before large area construction, all should first in the local small test, confirm the effect after large area use. Do oneself know well, can avoid the bad nursing effect that produces because of the material of stone island red and the mismatch of protective agent are incompatible. The specific selection method can be summarized as follows:

(1) smooth stone island hongxin no. 8 stone can be selected to increase the gloss of stone protective agents;

(2) the decorative effect requires to deepen the shidao red color should be selected to enhance the protection agent;

(3) to maintain the original appearance of shidao red should be used as a primary color protective agent

(4) when adopting wet paste installation, shidao red bottom surface should be as far as possible to choose the protective agent that does not affect the bond fastness between shidao red and cement mortar;

(5) in case of construction in a confined space considering environmental protection requirements, water-based protective agents or protective agents without volatile organic solvents should be selected as far as possible;

(6) stone shidao hongxin no. 8 stone surface or dry hanging stone surface, can be used waterproof protective agent can also be used detest water type protective agent;

(7) in case of frequent exposure to oil stains, oil-proof protective agents should be selected;

(8) if the ambient temperature is too low, the water-based protective agent cannot be applied due to freezing.