of a reliable
I think part of the confusion stems from the fact that many voiles appear to be woven as chambrays i.e. with a white weft. The voiles from SG appear to be also chambrays. Acorn also describe some of their voiles as chambrays i.e. "Chambray – a light-weight, plain weave cotton fabric having a coloured warp and a white weft, producing a mottled appearance. Our version of this is produced using a white warp and a coloured weft which enables smaller minimum productions – e.g. Zephyr"
By the way i agree with you that terminology is often used inconsistently and that professionals can often mislead the consumer. If I had a pound for every time I've been told "they don't make canvassed suits anymore" I'd have enough for another suit.