Silica is not typically used in epoxy resins because its primary use is as a filler and thickener, while epoxy resins already have good flow and viscosity. The addition of silica to epoxy resins may cause a color change and will not provide any significant reinforcing properties.

However, if you have specific needs, such as wanting to adjust the color of the epoxy or change its properties, you can try adding a small amount of silica, with the following caveats:

Testing and evaluation: Before actual application, small-scale testing and evaluation are carried out to determine the amount of silica added and its impact on the performance of epoxy resins.

Uniform Dispersion: Ensure that the silica is evenly dispersed in the epoxy to avoid problems with uneven color or lumps.

Other effects: Adding silica may affect other properties of epoxy resins, such as hardness, strength, wear resistance, etc. Therefore, these performance changes need to be fully evaluated before actual use.

In summary, silica is not commonly used in epoxy resins in general, because epoxy resins already have good properties. If changes in color or other properties are desired, appropriate testing and evaluation should first be performed to determine whether the addition of silica is suitable for your specific needs.