Lace wigs are created by looping hair onto a flesh-toned mesh, which will disappear against the skin when applied with an adhesive. Sometimes, the wig's hairline tends to be thick, creating an unnatural transition from your forehead and the hairline. The "wall" of hair can be avoided by asking the wig maker to use single, bleached knots, and more dispersed hair ventilation. If you bought a stock wig without these customizations, you can implement them yourself with a bleaching kit and tweezers to create a more natural wig hairline.
Purchase a custom lace wig to get the best lace wig hairline. By visiting a wig shop, the wig maker can create a template that matches the distinct shape of your hairline. Alternatively, many online wig shops are open to customers mailing in a template to ensure a custom fit. You will want a wig that is shaped after your hairline for the most realistic look.
Many wig makers will loop two hairs at a time into the lace so that the hair is reinforced onto the mesh material. This technique, however, creates visible knots that can give away the realism of the hair piece. Ask for single-hair ventilation around the wig hairline. The single knots are smaller and will be harder to detect by touch or sight. Also ask for the knots to be bleached, minimizing their appearance even further.
A lower hair density around the hairline should also be used. Natural hairlines blend from the forehead, into the scalp. A higher density unit will create an unnatural "wall" effect, with a strong contrast between the forehead and the front of the lace material. Ask the wig master to use fewer hairs around the wig hairline, allowing for some of the "scalp" to show.
If you already have a stock lace wig in your possession, then you can customize it — at your own risk. You can bleach the knots around the hairline by applying a light coating of hair bleach on the underside of the lace, making sure to follow the directions inside the instructional booklet. If the wig hairline is too thick on your stock piece, then you may want to remove some of the hairs with a pair of tweezers; turn the lace wig inside out, and gently pull on some of the individual knots to unravel and remove them.