Molly,
Been using LMF for 20 plus years with great, repeatable results.
Read the instructions and use a sweat box. The copper comes from too much rubbing, or rubbing too hard.
On a barrel, 2"x2" piece of rag, folded to 1" square, dampen with brown, take one light stroke from one end to the other, go to the next flat and repeat till done.
Like I said before, I use a sweat box, card every 3 to 12 hours, ( depending on the type brown you want) in 36 to 48 hours, I've got browning that you can't knock off with a hammer.