You can also repair a mirror crack using a specialized resin-based repair kit. Because each of these kits is unique, you'll want to follow the instructions included with your repair kit. This option works best for mirrors with small gaps resulting from cracks, as the resin fills the gap to restore a mirror's surface With this repair kit, you can easily fix minor cracks and restore the smooth surface of your mirror. Simply follow the step-by-step instructions included and you'll have your mirror looking like new in no time. Perfect for repairing small gaps and cracks, this specialized resin-based kit is sure to help you achieve the best results.