You don't need to grind them but you need to have a lot of hulls. I would start with a 4 qt. duchoven heaped wit hulls in a big pot with enough water to just cover. Let this stand over night then bring to a hard boil the simmer covered for several hours, may be 4 or 5. Only add enough water so you don't worry about burning. It's best to do this outdoors if you can. Let it stand over night with water about half way up the hulls. Strain off the hulls and reduce to about half. Cool it and try it on some scrap. If its too light reduce more, if its too dark add water. Good luck and please share your results!