"Soft as silk" is a phrase that is often used to describe something with a gentle and smooth texture. However, there are many synonyms that can be used to convey a similar meaning. Some alternatives include "smooth as satin," "delicate as lace," "plush as velvet," and "feathery as a cloud." Other options include "silky smooth," "supple," "malleable," and "yielding." Each of these phrases can add a touch of elegance and sophistication to your writing, while also providing a vivid description of the texture of the object you are referring to.