I have old stains spattered on the mattress and assume it may be urine.
Tried getting the stains out with carpet upholstery cleaner, sard oxy plus…
250700cookie-checkOld urine stains on mattress
Old urine stains on mattress
Chemistry in the real world
You tried Sard Oxy Plus? That might be tricky then. Try Preen Vanish OxyAction Gold. Spray on and leave it. If it doesn’t work, try Preen Vanish Carpet Foam