Etching

Engraving is a specific chemical process that makes PTFE tapes, sheets or finished parts glued to different substrates and materials.

Etching is a specific chemical process that makes PTFE tapes, sheets or finished parts bondable to different substrates and materials. The bondable side (acidated surface) can be easily distinguished from the typical dark brown color it takes after the etching treatment.

Such an etching process on the PTFE is a reaction between the sodium metal and the outer fluorine layer of the polymer, which is removed by a few hundred Angstrom leaving the carbon backbone free to create bonds with other surface.

There are two different etching techniques:

  • Sodium naphthalene: is less aggressive on the PTFE surface, which means that the skin resistance (N/mm) is about 1,90.
  • Sodium ammonia: penetrates deep into the surface of the PTFE resulting in a 3,15 skin resistance (N/mm).

However, sodium naphthalene is the only option for some specific products and applications.

High temperature, high humidity and especially UV light have a negative effect on the acidified surface. If not correctly stored, the etched PTFE can lose its bonding properties even in a few hours. If, however, properly stored the etching properties can last for weeks or months.

Due to this, we pack and ship all the etched material in black plastic bags, advising our customers on storage conditions and shelf life.

ETCHED PRODUCTS