The end of YouTube video Delta IV Heavy Pad Tour, (with CEO Tory Bruno) - Smarter Every Day 199 points to Destin's second "Smarter" channel's video UP CLOSE Delta IV Heavy Launch Pad Tour (Tory Bruno CEO of ULA) - Smarter Every Day where an extensive discussion of the Delta IV Heavy is given by ULA Pres Tory Bruno.
12:30in the second video, Bruno says (my best efforts at transcription):
(cork is) a very common rocket insulative material because not only is it a thermal insulator, it’s an abaltor which means that it erodes or burns off as it’s trying to heat up which helps to remove the heat before it can conduct in.
[…] And of course where we have our cryogenic propellants… I’ll let you look down here, and you’re going to look for areas that look really rough on the side of the rocket… so that’s an insulative material that we paint or spray on, called SOFI†, and that’s a polymer insulator, and it’s very similar. It will be thicker, a couple times thicker than the cork, and that does the same kind of thing, it ablates-off… and that important on these big guys because cryogenic propellants - they’re boiling the whole time…
†spray-on foam insulation https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110014400.pdf and possibly What exactly is the orange insulation foam used on many different launch vehicle stages?
Question: Are the ablative properties of the insulation at all important to reduce the boiloff rate of the cryogenic propellants? Why would rocket bodies use specifically ablative coatings to reduce boil-off of cryogenic propellants?
12:31, but the whole video is worth watching!