In the biblical Noah’s Ark story, pitch was used to seal the Ark against water.
Genesis 6:14 instructs Noah to cover the Ark inside and outside with pitch. Pitch is a dark, sticky waterproofing substance traditionally produced from tar or related bituminous materials. The instruction complements the Ark’s wooden construction by addressing watertightness.
Translations vary in how they render the Hebrew term, with forms such as bitumen, pitch, or asphalt appearing in English Bibles. These words point to waterproofing material rather than to a separate structural material. That is why the answer is not the type of wood used for the Ark.
The passage gives no modern chemical recipe or archaeological sample. It describes the function and placement of the coating: Noah was to apply it both within and outside the vessel before the Flood.