Colby...there are a couple of options but, I would recommend that if you are having problems getting lacquer into the slots while spraying the rest of the headstock. Tape off the front and back of the headstock with masking tape leaving only the slots exposed. Cut your spray pattern down and the amount of lacquer coming out of the gun. Cut the air pressure (about 40lbs)and this should allow you to focus on the slots first. Once you have lacquer in the slots...roll your sandpaper for the rounded edges...flat for the flat areas and wet sand the best you can. Be patient and sand and continue to spray until you have a good coat of lacquer in the slots. Once you feel you have the slots covered well, wet sand them one last time. Remove the masking tape. Then make a mix of relatively thin lacquer to shoot one or two last light wet coats just to bring back the gloss. This should also help to blend any edge build up from the tape. If the lacquer is thin enough you should be able to avoid the white coating you are talking about in the slots. This is usually caused from overspray. You need to focus on the slot areas first in your final coats then when you put the light coat on the front and back of the headstock the slots will be wet and blend more easily. It's real helpful to have good lighting and keep the light reflection where you can see when you have the areas covered. They will have a gloss rather than the white overspray...

Hope that makes since.
NOTE: When wet sanding the slots..don't use too much water. This can go into the tuner holes and cause the wood to expand and crack the lacquer.
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