Nothing on the bottom of the foot ?? Probably mid 1900`s or around then !! Wooden items used in the kitchen sometimes show more aging than others due to heat, steam and inevitable flying around of oil particles when cooking !! Wood will take on a sheen which yours has on the unpainted areas !! Paint will also darken a bit and get a richer tone !! So your guess could be correct about spices, salt or other condiments !!