As mentioned in a previous post or two, several weeks before Christmas I rec'd three of the DT silk lines from Zhu's.
Although I've read that several other forum members have coated the varnished lines "right from the box", I softened mine first, much like you're doing (except I have a little U-shaped gadget with a metal rod at the top where I do 4 or 5 line windings and then "shoe-shine" the line back and forth to soften the varnish coating). Once my entire line was softened, I THEN applied several coatings of Thebault line grease, (which I prefer to Mucilin when coating or recoating entire silk lines); letting the line sit for awhile: and then wiping off the excess line grease before coiling / spooling the softened / greased lines.
I don't understand how any of the line grease could penetrate a "hard" varnished / enameled line UNLESS the hard coating was first softened (i.e. - cracked, scraped, etc.) but then, there's lots of things that I don't understand (right Ed?).
After I was done with the softening / greasing, my three Zhus' lines are really nice and I would say, very close to or the same as the four Terenzio silks that I've had for several years.
Cheers and Safe Fishing
Bob

