You should overfill your damage as once the adhesive is applied to the damaged area it will shrink in volume by 20% as it hardens so cavities must be over-filled to allow for this. You need to ensure that your repair overfills the area by 2-3mm so that you do not sand away too much acrylic which could cause colour issues. When you apply the polythene use very light pressure to ensure that the solution doesn’t get pushed out of the damaged area. There is enough product to repair approximately 8-10 chips the size of a flat 5 pence piece with a depth of approximately 2 flat 5 pence pieces (i.e. 3-4mm). If you would like more information on how to fill in your repair please click here.