"Exposed to sea water, or salt spay, a military weight kilt in wool will self combust, which is why they are not worn on ships of Her Majesty's Navy when at sea."

and,

"I would also avoid exposing your kilt to the contents of your stomach, especially if you are on the bus home after a night out with the lads."

and...

"One should also avoid sitting on the ground in pastures, whether used to keep sheep or cattle."

and...

"Recently painted park benches also come to mind, and although it is just good old fashioned common sense, it probably would not go amiss to remind those new to the kilt that entering a flaming building whilst kilted should also be avoided."

The above are taken from:

So You're Going to Take Care of Your Kilt by Charles T. Jaympson, The Naptha Press, 1979 (third edition, with illustrations by the author's friend)