Have lost track of the specific brands over the years (I'm a perpetual scrounger)
But found that any way to concentrate the energy into smaller edge/area
helps the string work.
i.e. smaller diameter or sharp edged lines.
Drawback to the square or other non-round lines is increased tendancy
to friction/heat weld inside the string head.
Smaller stock can be easier to break off at the eyelet.
ether way we get to shut down and go pull the head apart,
desnarl line, clean the grit & debris out and go back at it.
have tried various sorts of cooking spray, WD-40,
old (gettin' scarce here) stock of dry PTFE ("Teflon") lube.
those sponge rings, heck even a wadded &twisted paper towel
or only winding 2~3 feet total of line into spool per loading
you get the idea of my agravation.
Best trick to date ??
A bowel of water.
Yep, Read it somewhere (could be here or that Lawnsite place)
Tried it last year by letting the line stay in the water
for at least a couple of weeks before using
(always covered by the water, keep topping off or changing the water)
Well wadda ya know
Hmm, made a nice improvement.
The engineers in the crowd here can give y'all the rundown on
how to figure for plastics absorbing water or other things.
some years ago I did read about it being a factor in designing molds
for plastic parts (varies by type stock used, etc...)
also Helps explain how plastics absorb oders!
results for me?
I've been running line that's at least 10 years old
and once it had a good saturation period and is kept under water,
I've not had any breakage or welding snags since then.
Now be aware I'll still snag an obstical that the string can
wrap it's self around and that's gonna snap anything,
no matter what it's made of...
edges of rocks, bricks, concrete & black top all will abrade and
weaken or grind away at it.
bottom line, try the *Continuous* underwater storage
and see what ya think.
Also helps to find string heads that are balanced and run true
better if the line is not vibrating/grinding against itself all the time
also better on the trimmer and operator.
good smooth bump head with the internal spring(s)
made in correct orientation for the heads rotation.
Wrong way spring winding/design tends to cause issues also.
learn to tap (not smack/beat) the head on firm surface
and if line is good not welding ,then you might experiment with
trimming a small bit of spring height/preload.
lighter spring tension gets an easier spool to use
but you gotta get your finesse up or it will just be bouncing
and spitting out line.
Gonna cork the spiel for the moment,
but go soak your line and see what you think!
if it works for ya, overvolting the electric ones or
A muffler mod and carb tune gasser will
suddenly have great appeal .