As someone who abhors over dense wigs on myself - I look ridiculous, figuring out density is, and has been, a pretty important part of my wig making journey. Unfortunately, once I started ventilating, it quickly became apparent that density is not something you can learn overnight, so to speak. It is one of those things you learn through practice and possibly some innate sixth sense. I am learning to trust my instinct a little more.
One of the reasons I think density is very difficult to assess and get right as a learner, is that it is something of a stretch to try and realistically imagine what an entire wig will look like (no matter how much you are dreaming of the finished product) when you are ventilating the nape or the back or even the crown. In my case, with the wig, I started off well and then panicked and imagined I was adding too much (I had visions of Attila the Hun), so I backed off and went super light and ended up with... well, not enough in one area.
Of course you may be thinking: 'ah, but you can always go back later and add more hair'. While this is true, I do not think it is strictly the best way to go about things. It is messy and I am a perfectionist. Adding hair on top of already ventilated hair is not really my cup of tea and it is also INCREDIBLY time consuming and slightly insanity inducing. You have to try and keep all the other hair out of the way while you work on an area, and take it from someone who has done repair work, that is no mean feat. I guess some wig makers probably enjoy or relish the task of repairs, I personally do not. I prefer to start with a tabula rasa, a blank slate, and go from there.
So for me, this whole wig density business is something I am trying to get right. As I may have discussed before on this blog, I am a person who needs a lighter density and volume on the top, but I quite like more lushness going on from say the ears, downwards. My own bio hair was like that - flattish to the head and then lots of it around my shoulders and going down my back - and it does tend to suit me a lot more than the puffy wigs.
Where I am running into issues now is getting enough density at the front of the wig so that it hides the foundation, especially the galloon, and yet does not look fake. The front of the wig is probably the most important area to get right - that and the part line/crown (which are exposed). Generally people are looking at you/your hair more closely when they are talking to your face. As a result, I am now ventilating quite densely into the galloon at the 'sideburns' area. I have been striving to cover it up before starting to ventilate into the lace above it. I feel as if I am stumbling blindly around, but I take comfort from the fact that this wig is meant to be a learning curve and a practice session.
Image is clickable - click to enlarge. On the left is the beginning of the heavier ventilation to hide the galloon from the front view when on the head. On the right is sparser ventilation into the galloon, as no one will see this area because it is covered by hair and unlikely to be exposed. The paper is inserted in the pocket I have made for wig springs, that I don't want to 'sew' together by ventilating hair into both pieces of lace!
This just goes to show how you do not necessarily have to ventilate extremely densely to make a wig work. However, there is a fine line between under-ventilating hair into an area (as I have found out) and over ventilating so that you end up with a wiggy, hot mess (quite literally). Certainly when you are getting near the part line or the front, it is worth bearing in mind what type of base you are trying to cover. If you are ventilating a full lace wig or a lace front, then beautiful, natural, graduated ventilation is the key and it works REALLY well. If you are making a wig like I am, where you have a base that is seamed and has galloon edges, you really need to be conscious of the fact that if you do not ventilate densely enough into this area, you may expose the wig foundation (base).