Over 70% of the travertine that is quarried and filled is filled with Tenax brand of travertine filler. It is a better product than traverfill as it has more isometric properties than traverfill, which is made by superior and marketed through Custom building products.
I had this same conversation with a customer today. Since the Tenax brand is a semi solid it will fill the holes it is pushed into unless they are less than 1/16" . They may work on holes smaller than that but only if there is something for them to cling to.
This is the recommended product:
http://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Tenax-Travertine-Filler/c82_506/index.htmlGlad to be of service,
Mark