Well what can I say but here's one postive vote for cold soaking and rinsing! What it does is remove the barnyard from the fleece before you do the hot wash so the hot washing will remove the lanolin and other ickies that cold soaking does not get rid of!
I have about three pounds in the washer right now, it'll be rinsed in about 30 minutes and if it's satisfactory will go straight into a pine green dye vat. I'm cheating I'm using acid dyes, country classics to be exact, no one around here wants to pay for fibers dyed with natural dyes, though they all claim to be Eco-Friendly and fight to have the most carbonless footprint in existance. I will be dyeing about half of this fleece with natural dyes - indigo and osage orange.
Silver Romney lends itself quite well to becoming green ;-) I have a lovely poundish amount of terra cotta as well. I got that by mixing half a container of Butterscotch with a heaping teaspoon of Turkey Red, very lovely. My next batches will be blues, teals, and purples as silver romney doesn't do yellow very well, it looks odd.