I've done a number of decal kits on 70-81 Trans Ams.....if you know the cars, you'll know they have a roughly 4 foot x 4 foot phoenix decal on the hood which scares the heck out of people to put on.
I always do the decals wet......this means applying them over a sprayed on solution of water with a few drops of pure dishwashing soap in it to break the surface tension....the mix just needs to be a little bit soapy to the touch.
-Clean the area thoroughly with wax and grease remover or de-natured alcohol and lint free soft cloth.
-I position the decal using a couple of small pieces of masking tape (the "easy remove" stuff works best). I mark a centre line in pencil on the decal cover paper then measure to ensure the decal is square and centred where I want.
-Once positioned correctly, I then apply a series of small pieces of decal around the outer edges of the decal cover paper onto the car and jsut butting up to the decal. This allows me to draw penciled lines across from the decal cover paper onto the pieces of masking tape. You end up with a series of "locating" marks around edge that will allow you to line up the decal when applying it.
-Lay the decal face down on a flat surface and remove the the backing paper.
-Spray the back of the decal and the surface where the decal will go on the car with the soapy water solution (use a trigger spray bottle)
-Lay the decal in position and float it around to align with all the previously marked alignment lines.
-Starting from the middle, use a squeegee and work the water/soap solution out from the centre of the decal to the edges....take your time and ensure the decal doesn't shift. After getting the initial water out, the decal pretty much starts to stick down.....keep working and ensure you work all bubbles out to an edge. Lettering is easier in this respect as there are lots of edges and not a lot of actual decal area.
-After getting all the water/soap mix out, leave the top paper on the decal and let it dry for 3-4 hours (warm day) or even overnight.
-When removing the cover paper, get one edge of the paper up, then slowly peel it back against itself ensuring that you do not pull the cover paper "away" from the surface (90 degrees to the surface) but you pull basically at 180 degrees to the starting point.....this is so there is minimal load on the fresh decal.
-Any small bubbles can be pricked with a pin, then use the sqeegee to work any solution out. Very slight bubbling/mottled appearance will dry out over a few days, depending how warm it is.
Heres a pic of one of he decal kits I put on a friend's 73 Trans Am using the above method. Its not the only way to do it, but it makes it easier to stop wrinkles and ensure the alignment is correct.
