Echo Trimmer Line: Sizes and Which One to Run

Echo's own copy on the Black Diamond spool notes it works with most gas or cordless trimmers that take .095 in line - a reminder that the printed diameter and what a head will actually accept are not always the same conversation.

Round line is the default and the most forgiving. It has no cutting edge, so it works by impact - fine for soft grass, slow through anything woody, and quietest of the three.

Twisted line, like Echo's .095, adds square edges along a spiral. Echo's stated case for it is lower noise and less vibration than a straight square profile while keeping the cutting edge. In practice it is the sensible all-round choice for a machine that sees mixed work.

Square line, including Black Diamond, is the aggressive option: four sharp corners that cut rather than tear. It goes through heavy weeds noticeably faster and it wears the head faster too, because those same corners chew at the eyelet on the way out.

If line keeps breaking at the eyelet rather than at the tip, the profile is not the problem - see trimmer heads.

Heavier line looks like a free upgrade and is not. Three things push back:

• The head has a rating. A head built around .095 in will bind on .105 in - the line cannot feed cleanly through eyelets sized for something thinner.
• The engine has a limit. Thicker line has more drag through grass. On a small-displacement trimmer that shows up as bogging at full line length, and the machine spends its life on the edge of stalling.
• Run time falls. More drag is more fuel, and on cordless machines the effect on battery life is dramatic.

The right answer is the diameter your head and engine were designed around, in the toughest profile they will feed cleanly. Going up a size to solve a cutting problem usually means the line is old rather than too thin.

Nylon line absorbs moisture from the air and becomes brittle. A spool that has sat in a shed for two summers snaps constantly, and every snap gets blamed on the machine. Two things help: keep the spool in a sealed container, and if a spool has clearly dried out, soaking it in water for a day before use restores a useful amount of flexibility.

The tell is where the line breaks. Breaks near the tip under load are normal wear. Breaks close to the head on light grass, repeatedly, mean either a worn eyelet or line that has gone brittle.