Hmm...perhaps the water supply is a factor...I don't know...while Delta 400 in a smaller format would reasonably be expected to be grainier than Delta 100, "very noticeable" grain in 8x10 prints from 645 leads me to wonder what's wrong since that shouldn't be the case.(posted 8130 days ago)I'd suggest you try D-76 or ID-11 1:1 using Ilford's development recommendation as a starting point, and mixing at least the stock with distilled water may be worthwhile.