Basalt Rovings typically start a around 270 tex (18 h.y.p.p) and can exceed 4,800 tex (1.04 h.y.p.p).
Note: tex means (grams/1,000 meter), h.y.p.p means (hundred yard per pound)
Rovings have a very low or mostly zero twist. For the most part, they are woven in from a creel, but they certainly can be warped, as well. In general, do not require to be slashed. .... read more about slashing here
The Filament Size:
For the most part, roving filament diameters start at 9 microns and go up to around 24 microns.
Rovings are multi-filaments and a strand consist of hundreds of single filaments.
If a manufacturer elects to make a roving based on 9 mcm, they need to have more single filaments to build up the desired density as if they were to use e.g. 18 micron. In fact, they would need half as many filaments.
The filament size largely determines the flexibility of the strand. Therefore, the choice of filament size depends on the application.
The scale of economics:
Due to a larger micron size/ filament, the output is larger than with smaller filament sizes. For that reason, rovings can be produced cheaper than the yarns.
Sometimes, manufacturers assemble rovings. In this case, they first manufacturer e.g. two bobbins of 1,200 tex and then later put them together on a new bobbin and create a 2,400 tex roving.
Sizings are also called binders. When extruding the fiber, the manufacturer sprays a chemical on the strand of filaments which has the purpose to
- keep the fiber flexible,
- mechanically protect it for upcoming textile or other processes,
- allow, enhance the adhering process with resins or coatings,
- create other additional properties.
For that reason, it is important to make sure to verify the resin compatibility for the intended application or textile process.
TIP: When testing samples, make sure you buy from the same source, as the outcome may differ, based on the chosen source!