Can Hair be Single Donor and Double Drawn?
Let's break this down:
If you cut the hair off one donor, the longest hair may be 18", however not all hair from that donor will reach 18" in length. Biological hair is present at different stages in the growth cycle, therefore hair can range from 2-18" (yes two inches). For scientific explanations about the human hair growth cycle, check out this article on Wikipedia.
Through experience processing hair, typically 10% of the hair from a donor reaches the longest length. In our experience, it typically takes hair from 6-10 donors to produce a full weft of double drawn hair. This is the downside of double drawn hair: it's thick and full at the tips, however there are various donors mixed.
It is for this reason that cuticle aligned double drawn hair is very expensive, if you see inexpensive double drawn hair, it's likely cuticle stripped because the roots and tips are mixed. This is usually the fallen hair from processing cuticle aligned hair (falls to the floor or table and is collected and processed).
Single drawn hair tends to taper at the tips and can range from very tapered to pretty full, some people refer to this as "thin", "scraggly" or "tipsy", however this is completely natural. Even though it is natural, most customers do not like this look because they often have to cut a few inches off the hair to achieve fullness at the tips.
The other method of drawing hair is to remove some of the shorter hairs but leave more longer hairs, providing more fullness, but also not mixing as much as double drawn hair. This is a very natural looking compromise between the two.
So, getting to the point, it is not possible to have a full weft, from one donor, that is double drawn. You could have a full weft, from one donor, with fullness at the tips, but it technically would not be double drawn, it would just be very full single drawn hair.
Also, single donor hair tends to be of varying weights. For example, if you cut the hair from one donor, it may be between 120 grams and 240 grams (on average), therefore a company processing the hair would still use all the hair. So, typically single donor hair is wefted as it is collected and sold be weight, and not by an even 100 grams, 4 oz or 3.5 oz.