National Model Railroad Association Master Model Railroader Gerry Leone shows how to change the numbers on the side of a manufacturer car in this video. The first thing to do is remove the existing number from the car. Modelers have found many different ways to do just that. Methods depend on the manufacturer, on the type of ink, decal, or paint they have used to number or letter the cars.
Modelers have used Soft Scrub with a q-tip, using the abrasiveness to gently remove the decal. Rubbing alcohol also works, as do ink erasers available at art stores, and MicroSol for some manufacturer cars. To renumber the car Gerry has in this video, he will use a sanding pad with a 2,400 grit. The Sante Fe car has a preprinted number from the manufacturer. Gerry uses the sanding pad to gently erase that number by sanding it down. He folds the pad over and uses the smaller surface area created for precision. He advises to be patient, as this takes a bit of time. Be careful to not also remove the reporting marks or dimensional data.
The important aspect of sanding or any other method of decal removal is to not disturb the paint underneath the number of the car. To prevent this, don’t sand in one area for too long or too hard. Once the numbers are completely gone, he puts a gloss coat over it again with a floor wax and then lay down the new decal.
The manufacturer has supplied a decal sheet with many random numbers, so by cutting out a block of those numbers he is able to create the new car number. Once dry and settled on the gloss coat, he uses a MicroSet and MicroSol combination to set it down over the rivet lines. He then applies several dull coats on the entire side of the car. This is how Gerry Leone creates unique numbers on his cars.