On the USS Missouri BB-63
“Holy Stone is actually soft sandstone, a sedimentary rock formed by the consolidation and compaction of sand and held together by a natural cement, such as silica. Holystone is all one word in the USN and you really don’t want to be the one doing it. When you Holystone Teak you use liberal amounts of sea water. (It’s only done in peace time. During WWII the decks were painted deck gray, which is really a dark blue, to camouflage the ship from air attacks.) After holystoning the teak becomes sort of ashen white and it’s really pretty. Our shoes had black rubber heels and you could put a black mark on the teak. If you did, you damn well better not let a boatswain see you or you would be doing hours of holystoning.” — Gene
The teak decking used on the US battleships is 2” thick — an old dimension from when a 2×4 was actually a 2”×4” measurement. In the USN the teak is bolted to the steel decking, with the nut and washer recessed into the teak and a teak plug covering them. The natural oils in the teak make it weather resistant and an excellent insulator against heat. Footing is good on teak, which is why it is used extensively on sailboats as well.
Teak retains a very pleasant aroma for a long time, making it a prime wood on cruise ships as well as warships. Even though teak has natural oils, a ship at sea soaks up salt water which swells the teak and keeps it tight-fitting. Left in the sun with little water, the teak will shrink and become loose.
The USN applied teak directly to steel decks — the oils in the teak prevent the steel from rusting. In areas such as the bridge, teak is usually lacquered, installed in sections with about a one-inch spacing and a foot of clearance below for seawater runoff. The sections can be lifted for cleaning underneath. The quartermasters keep this teak polished and waxed.
Another use of teak in older battleships was as backing for side armor. In the diagrams of the IJN Kirishima, the side armor was backed by 50mm (2 inches) of teak. Since Kirishima was built to a British design, teak armor backing was likely used on other ships of the same period. Beyond its hard-wearing properties, teak has an important advantage in warships: its oil has antibiotic properties, so teak splinters do not tend to become infected. — Gene