Nitro on the sealer is definitely not a problem. In fact, I'm burying a decal in nitro on roasted Maple headstock right now. First, I burnished the whole neck. Then I mask everything off but the face of the headstock, put a couple/few coats of nitro on so you can sand it back to a nice, smooth surface for your decal, then a mist coat to seal the decal, then several coats to build some thickness, then start level sanding back over the decal and recoating repeatedly until the edges of the decal disappear, then a couple more coats for good measure, then level sand/buff/polish. Works great. Uses about a half a rattle can of Reranch.