Raye's is the only working stone ground mustard mill in the United States.  Raye's got its start milling mustard for the then prominent sardine industry in Down East Maine.  Their last customer was bought out last year and the new owner switched to dry mustard powder.  Fortunately Raye's has developed a thriving business selling both mail order and through its retail store, the Pantry.  The giant outdoor vats pictured to the right were used for holding the seeds for their "factory mustard" - the mustard that was used for canning sardines.

The process is simple.  Crushed mustard seeds (three kinds are shown above - yellow, brown and oriental) are mixed with water, distilled vinegar, and salt.  Turmeric is added for yellow mustard.  Then the slurry flows through three stone (quartz) mills (upper center right), making it thicker and thicker with each milling.  The mustard is then barrel aged for a while to take away some of the bite.  Finally the mustard is hand jarred and labeled, two jars at a time, using the apparatus to the right.

Nowadays Raye's sells their basic mustard as either "Factory Mustard"  or "Down East Schooner Mustard."  It's yellow, but don't let that fool you.  French's it's not.  Raye's yellow mustard packs a nice kick.  Rosie's Hot Dog's (see separate listing in New England section) uses factory mustard for their dogs.

Raye's also makes a number of flavored mustards.  You can try them at the museum.  I picked up a jar each of Garlic Honey Wine Mustard and Raspberry Wine Mustard.