Fiberglass yarn Nomenclature

Fiber Designation Glass-Cut	Nominal Filament Diameter (Microns)	Nominal Filament Diameter (Inches)
B	3.5	0.00012
C	4.5	0.00018
D	5	0.00021
DE	6	0.000256
E	7	0.00028
G	9	0.00037
H	10	0.00043
K	13	0.00051

US Glass System - Example: ECG 150 3/2 3.0S

The example above, identifies the following yarn:

E = electrical glass
C = continuous filament
G = average filament diameter of 0.00037"(9 Micron)
150 = 15,000 yards/lb. nominal bare glass in basic strand.
3/2 = two plies of 3-strand construction (total 6 basic strands)
3.0S = the number of turns per inch in the twist of the final yarn in the S direction

Frequently Asked Questions

What does EC9-68x1 mean in glass yarn?

EC = E-glass continuous filament; 9 = filament diameter code; 68 = tex (grams per 1000 m); x1 = single ply. The code packs diameter, yield and construction into a few characters.

What is the difference between E-glass and C-glass?

E-glass is the general-purpose electrical-grade fiber; C-glass has better chemical resistance for corrosive environments.

What does tex mean for yarn?

Tex is the mass in grams of 1000 m of yarn; a lower tex means a finer yarn, a higher tex a heavier one.