Mr. Surfacer is a range of surface primers that can be used as gap and seam fillers as well as primers used by model makers and sculptors. There are three grades of Mr. Surfacer - 500, 1000 and 1200. Like sandpaper/emery cloth, the lower the number, the coarser the granules. The Spray version of the popular Mr Surfacer 500, supplied in a 100ml spray can, is ideal for larger areas.
Mr. Surfacer can be used for filling in bumps, scratches and pits. If the hole is large, use several layers, keeping each application thin so it dries thoroughly. Mr. Surfacer is also great for filling in seams. Once it has dried, you can remove any excess with a swab dipped in rubbing alcohol (IPA). The alcohol will soften Mr. Surfacer and rubbing it will remove the excess or it can be easily sanded.
CAUTION! Mr. Surfacer does dry very quickly. Also, remember that Mr. Surfacer is lacquer-based so you should complete as much of your filling and finishing work as possible before applying paint, especially enamel. Lacquer-based products can cause severe cracking, splitting or bubbling on enamels. To avoid this, you can use Mr. Surfacer 1200 spray as a primer or another lacquer-based primer on areas you find that may still need work.