[areoform]

Honestly, unsure! From my (imperfect) memory, the F-1 engine's thermal protection system usually isn't mentioned.

If it helps, other parts of the rocket were coated in asbestos too, btw. The Reaction Control System had asbestos, https://ntrs.nasa.gov/search.jsp?R=19730017174

And many, many other parts, including the cabins, https://www.smithsonianmag.com/air-space-magazine/a-saturn-v...

Here's a report for the command module, which starts with a very funny quote, "The JSC Director waived the use of the International System of Units (SI)for this Apollo Experience Report because, in his judgment, the use of SI units would impair the usefulness of the report or result in excessive cost." https://ntrs.nasa.gov/api/citations/19740007423/downloads/19...

[taeric]

Asbestos was used pretty much everywhere you wanted to contain heat. I recall watching videos of people with a fabric of it on their hands and a butane torch aimed at it, to show how effective it was. Usually in lectures that were explaining why it was used in applications like jets/rockets. :D