Floquil Crystal Cote, Glaze, and Flat Finish
Once decaling was complete, I would usually spray either Crystal-Cote or Glaze to the model to seal in the decals before weathering. Floquil Flat Finish was always an ingredient in the weathering colors I concocted to spray on the decaled models. Some Glaze or Crystal-Cote might be mixed in as well to achieve the look I may have been aiming for.
After the weathering layer dried, I might even spray the model with some mixture of the Trinity to tweak the final finish and seal in the weathering layer. A hint of a secondary weathering color might be included at this level. I found that several clear layers as well a a weathering layer do an excellent job of hiding the edges of the decal film.
While I still have a few bottles of the "Floquil Trinity" in my secret stash, I guess it is time to search for a replacement. What are the expert painters using today? I have seen posts touting the use of aerosol cans of flat or gloss finish, however I do not intend to point an aerosol can at my models!
I pulled out of couple of CCBX ElastoFlo covered hoppers I painted and weathered several years ago to review. The aim for these cars was a very light weathering with some luster in the finish. The Floquil Trinity was used to achieve this.