Hi there.
BRAND NEW to the forum. YET to purchase or build my 1st piece of equipment. Reading a lot. LONG story, but only moving to new location at the end of this year, and wife informs me I have to fix house roof and a bunch of other stuff before I THINK about laying 1 piece of track ... .. Anyways, one thing I have noticed a lot of in various threads, on many forums and personnel web-sites is the lack of "yachting / boating experience". To this end, almost ALL modern plastics are dishwasher safe if you use a cool to mild setting and a SMALL amount of regular liquid dish soap. Do not worry about the bubbles escaping all over the place if you put too much in, just run an empty "eco" cycle after ! Some regular "dishwasher" soaps are actually quite chemically harsh. So without trying it myself 1st, will not vouch for them on the sleepers. But a lot of my yachting stuff goes in my dishwasher when wife not looking. As to pressure washers.. go for it, but on a wide fan or lower power setting. I have seen the paint and primer completely removed from a car from a pressure washer set a little high.... (ok was a BIG pressure washer)