This retro printed sheet combines hot pink, tangerine and orange, with white highlights, in an abstract stripey pattern. It is very reminiscent of a mod color combo from the 1960s (think the Barbie movie colors).  I believe this sheet is from the 1970s and was made by Martex of 50% cotton/50% polyester.  I saw a tiny ink spot near one corner (it would be under the mattress so not visible on a bed, but it may have been a flaw in the manufacture because it looks like the color ink used to stamp "Twin Bed" on the elastic corner.  (See photo.)