Glue is the best for hairlines. How many layers do you use? I hate ghost bond. Have you tried ORWG or invisibond or safe grip? I get the same problem where I can see the lace pattern if I look closely. To fix it I just add more layers. 4 layers of glue at the very front makes a thicker area for the lace to sink into and this is what makes it disappear. Also something I used to do wrong was not pressing it in hard enough. I have to really press hard with the comb to get it to sink into the glue and disappear.