Advice on painting over Vintage Tint nitro satin finish

[Matt]

An artist friend has offered to hand paint a design on a headstock which is covered in a Vintage Tint nitro finish.
She is wondering:
1) what prep is necessary that would allow the paint to "take and not harm the finish, and
2) what type of paint and sealer should she use that would allow the paint to adhere well, not be affected by the finish, and not damage the finish?
Anyone have experience with this?
Matt

 

[Cowbell Fever!]

I would go with bug secretions, then oil paint.

 

[ragamuffin]

1.) I'd say lightly sand the surface where they're going to paint with around 320 grit sandpaper so that it will adhere well.

2.) I don't have first had experience with this, but I think acrylic paints are generally used for that type of thing. Then coat with nitro to seal.

 

[NedRyerson]

I offer what I did recently as a suggestion:

https://www.unofficialwarmoth.com/index.php?topic=33979.msg470262#msg470262

A (very) light scuff to prep the surface for the acrylic paint.  I went with 400 then 600 with just enough pressure to let the sandpaper do the work.  Then came the painting.

After drying, I lightly knocked down some of the peaks in the paint with some more 400 (very, VERY carefully, lest I scrape off too much).  Then came the "bug secretions" as Spud said, or what we like to call "shellac."

After the shellac dried, then I applied several coats of gloss lacquer to protect.