How to Refinish a Bathtub 1. Clean Tub Remove hardware and the old caulk from the bathtub. Clean the tub thoroughly with a degreaser. 2. Repair Chips Mix a two-part epoxy filler until it forms a paste consistency (Images 1 and 2). Next, apply epoxy with a putty knife to fill any chips in the tub’s surface (Image 3). Scrape excess epoxy with the putty knife to reduce sanding time later (Image 4). 3. Smooth Rough Spots Once the epoxy hardens, smooth any rough spots with a utili