A lot of our textures are odd sizes that look ugly when you're using mipmapping. Forge gives this warning about each of them at startup:

Texture mekanism:textures/X with size X will have visual artifacts at mip level 4, it can only support level X. Please report to the mod author that the texture should be some multiple of 16x16.

While #5834 is a duplicate of this I am closing this in favor of that one as it is a more detailed report.