With all the spray finishes, please make sure that you shake the can vigorously for at least two minutes to mix the finish thoroughly. If you do not do this, most of the spray will be solvent, which can damage the decal print.
After shaking, spray on a very light mist coat, all over the sheet, from about 18" away. It should be only enough to just cover the surface, and not too heavy or it will damage the decal. This light mist coat seals the surface.
Wait at least 15 minutes, and spray on another light coat from about 12" away. It should only need a light coat. Too heavy and the decal may become too thick and not bend as easily.
Let the decal sit at least a day or longer before you use it.
Spray Finishes that I have tested and know that work:
Krylon Crystal Clear Acrylic Spray
Krylon Preserve It! Gloss
White Knight Crystal Clear Acrylic
Dupli-Color Top Coat Clear
3m Acrylic Clearcoat
Helmar Crystal Kote Gloss
Micador Crystal Clear
Tamiya TS13 Clear - I have had a report that this does not work in all cases.
Digi Coat PDC UV400
There are other finishes that should
work. Test them on a small piece of decal first before doing a
full sheet. Let me know if you use one that does so I can add
it to the list.
Some that look very similar to the above are:
Keen Crystal Clear Acrylic
Humbrol Crystal Clear Acrylic
Finishes that can be applied by brushing or by Air Brush:
If brushing, apply with a large soft bristle brush or a sponge brush, and use very slow strokes to avoid bubbles.
Future Floor Finish (e-mail for a sheet on this and where to get
it in your country)
This is not the best solution, and some curling can still happen after applying.
Microscale Liquid Decal Film
The above finishes can be found at Hardware Stores, Hobby Stores, Auto Parts Supplies and/or Arts & Crafts shops.
Brands that do not work:
Testors Clear Coat
Please let me know if you find any more to add to this list.
The following have been tested
with notes by a customer:
Tamiya Gloss Clear Aerosol: Decant from can into airbrush bottle & spray 3 or 4 light mist coats. Let dry for 15 min & apply glossy "wet" coat. There is no need to thin this paint. Built up a nice gloss, but Micro set & sol did not soften it. This works fine for flat or single curved surfaces.
Tamiye Gloss Acrylic thinned 50% with distilled water: Spray 3 to 4 mist coats (very light and fine as this stuff runs very easy). Responds ok to Sol & Set.
Microscale liquid decal film: This worked like a charm! I sprayed it through the airbrush (2 mist & 1 heavy coat). It dries matt, but seals all the elements of the decal together and works excellent with Micro Set & Sol as well as the new Tamiya Mark Fit decal solvent on complex curves. After application it can be clear coated to build the gloss.
PS. The above finishes can also be used with the new waterslide decals after they are installed on the car, using the same application technique