Dry transfers also have a shorter shelf life than decals, as they seem to dry out as they age.
Once you get them in place, don't skimp on the burnishing step - with proper care, you can make the lettering look like it's been painted on, even over rivets and seam lines. For areas that are difficult to burnish due to limited access, a strong decal setting solution, such as Solvaset, will work on dry transfers, although burnishing is preferable when possible. For irregular areas, you can apply dry transfers to clear decal paper, overspray it with a clear finish, such as Glosscote or Dulcote, then use it as you would a regular decal. I find this is very handy for doing the reporting marks on the ends of freight cars.
Dry transfers are also handy as a paint "mask". For this, the colour of the dry transfer lettering is not important, and the lettering should
not be burnished in place.
To use dry transfers in this manner, first paint the model the colour that you want the lettering to be. Next, apply any lettering and mask (using either tape or dry transfer stripes) for any striping that's to be the same colour as the lettering. Now, paint the model the proper colour, and as soon as the paint is dry to the touch, use bits of masking tape to "dab" at the dry transfer letters and striping. The tape will lift the letters, revealing the underlying colour.
I used this method to paint and letter the locos shown below, as, at the time, there was no lettering available for these diesels which was the proper colour. All lettering and striping on the bodies was done by using dry transfers as masks, after first painting the underlying areas the proper colours. I used alphabet sets, although the herald on the cab side was done freehand, using a fine brush. The entire model was brush painted, too, using custom-mixed Polly S (not Polly Scale) paints. These diesels, and the method, were featured in Paint Shop, in the Feb. 1980 issue of MR. Eventually, C-D-S released dry transfer lettering for a freight car that had the proper-size herald, making this job a bit easier, and eventually came out with a decently-coloured version of the lettering especially for these diesels. I painted several dozen of these locos for an LHS, until LifeLike Canada finally came out with an extremely well-done r-t-r version.
I used the same technique to letter some of my other locos, too.
Wayne