Applying knot-sealer to the underside of the base helps to keep this issue to a minimum....it`s a liquid which forms an acrylic skin and seals the knots into place... it`s best not to apply it on day one --leave time for the hair to settle into whatever style you groom it to, especially with Freestyle venting..... a bottle of knot sealer is sufficient to ` treat` around 6 toppers so go easy with it ... you only barely dab it on ...you shouldn`t see wetness as such....if you apply it too heavily it can seep through onto the hairs and cause them to clump into lumps.....it can help prevent hair shedding out from knots becoming undone also.... there are vids. on `Youtube` showing how to apply it ..... Here`s Debbie showing how it`s done :
https://www.youtube.com/watch?v=ZOUDBdJvay0