Snowbee do two bottles of line treatment.
One is the line slick for as far as i am concerned all floating lines or floating bits on sink tips.
They also do a line degreaser, for removing the silicone that leaches out of sinking lines and makes them float, degtrease them and they sink as they should do.
There is a product called Permaplas, which has been on the market as long as I can remember which is said to "revive tired and cracked fly lines by replasticising the coating".
Not sure if it is for all flylines or just floaters, but would assume floaters only.
I have a tub in a drawer somewhere but not used it in seasons as i think fly line durability is far greater than when Permaplas came out as a product.
I find regular cleaning then slicking or degreasing works fine.
---------- Post added at 01:38 AM ---------- Previous post was at 01:28 AM ----------
Went and found the Permaplas.
Intructions say;
Using pad, grease the line liberally with permaplas, let it stay for 4hours, then clean off the surplus with a dry cloth or tissue.
There is s note on the bottom of the tub which says;
The directions given apply to floating lines, apply sparingly on sinking lines.
I also found another tub of stuff from Lureflash, gods knows when or where I got it. It is called PLASTISINK and claims "cleans, plasticzers and reconditions SINKING fly lines".
Looks like I have used it, but god knows on what as I can't remember.