E-Glass Yarns

Product Description: 

E-Glass fibers are produced in a pultrusion process; by its own weight, the molten glass is conducted through a bushing.

A bushing has multiple hundred holes of which each represents the formation of a filament. All filaments combined form a strand of the final yarn.

Immediately, when the filament is formed, a seizing needs to be applied in order to keep the filaments flexible, prevent them from breakage and protect them for later to come textile processes. The seizings are also designed for the final application and therefore may consist of ingredients such as “Acrylic”, “Parafin”, “Silane”, “Starch-Oil”, or other.

Besides the choice of the seizing, the End-User also has a choice of various filament diameters and various yarn densities. The choices heavily depend on the final applications and the production steps necessary to develop and produce the desired final end product.

Culimeta E-Glass products are in compliance with ASTM D 578-98, Section 4.2.2.

Chemical Composition: 

Al(2)O(3): 13% – 15 %

SiO(2): 51% – 55%

CaO: 20% – 24%

Balance: B(2)O(3), K(2)O, Na(2)O

Basic Yarn Types:

  • Yarns unprocessed
  • Yarns Twisted
  • Yarns Texturized
  • Rovings


Yarns have a very low twist, for protection of the product, Typically they have a lower density and filament diameter.

In most cases, they are the raw material for dyeing, texturizing or twisting,

Yarns Twisted

Yarns are twisted, if one or more strands have experienced a pre-defined number of “turns/ inch” or “turns/ meter”. In most cases, the final twist is in a S-Direction..

In order to twist two or more yarns in the final S-twist, they need to be pre-twisted in the opposite direction which is called a Z-Twist; this is to balance out the Yarn’s “recall-effect”, the desire to twist back into its original form.

Sewing threads have a very high twist, typically in the Z-Direction.

The product can be “ring-twisted” or “direct cabled’, “assembled”, or also called “false-twisted”. Depending on the final application, the End-User can decide for one of those choices.

Yarns Texturized

In brief, one or multiple strands are mechanically bulked by applying compressed air.

Usually, texturized yarns increase the insulation values of the final product, or contribute to aesthetics in decorative applications.

Please click her for a detailed explanation: Detailed Documentation on Texturized Products


Rovings normally have higher filament diameters and higher densities than the yarns described above. Typically, they have different seizings, more applicable to reinforcement applications.


The Letter “E” in E-Glass stands for excellent “electrical” properties. For this reason, this fiber is widely used in fabrics, tapes, scrims etc, for electrical insulation applications; in many cases, the fabrics, tapes, etc will need to be treated with chemicals in order to further enhance the electrical insulation values.

As one of the most widely used, it also is one of the most economical of the Glass-Fiber  families, It therefore is also commonly used in thermal applications.

The US-Nomenclature e.g. differs from the European Nomenclature.

Below is a conversion table to provide an overview and comparison:

Conversion tables
Filament diameter
European unit microns   U.S. symbols   inches
1 micron =  1/1,000 mm 5 D 0.00021
 = 0.001 mm 6 DE 0.00025
 = 0.00004 inch 7 E 0.00029
9 G 0.00036
10 H 0.00042
13 K 0.00051
14 L 0.00056
17 N 0.00068
24 T 0.00096
Turns per inch (TPI): 1 TPI = 40 turns per m (T/m)
Weight of yarn
Metric   Yard   Metric   Yard    
tex (g/1,000 m) h.y.p.p. (100 yds/1lb) tex (g/1,000 m)   y.p.p. (yd/1lb)
2.8 1800 h.y.p.p. 160 tex 3100 y.p.p.
5.5 900 660 750
11 450 1100 450
22 225 1200 416
34 150 2400 207
68 75 4800 104
tex = 5,000/h.y.p.p. h.y.p.p. = 5,000/tex tex = 500,000/y.p.p y.p.p. = 500,000/tex
hundred yds per pound yds per pound exact: 496,238
Mass         Force
1oz. = 28.35g 1g = 0.035oz. 1N = 0.102kgf = 0.225lbf
1lb = 0.454kg 1kg = 2.205lb
Length         Area
1yd = 0.91m 1m = 1.09yd 1sq.yd. = 0.83 sq.m 1sq.m = 1.19 sq.yd.
1ft.(1/3yd) = 0.3048m 1m = 3.281ft. 1sq.ft. = 0.039 sq.m 1sq.m = 10.76 sq.ft.
1inch (1/12ft.) = 2.54cm 1cm = 0.39 inch
Density         Temperature
1lb/in(3) = 27.68g/cm(3) 1g/cm(3) = 0.036lb/in(3) 1,000 degr.C = 1,832 degr.F
1lb/ft(3) = 0.0160g/cm(3) 1g/cm(3) = 62lb/ft.(3)
This conversion table is a guide and to our knowledge is accurate.