if possible size wise ,I'd clean it with mild soap & water or use a alchohol wash or spray to remove pastels & oils and such then give a coat of your favorite color. ...Jerry
Not sure where painting over dullcoat comes through in your question if no sealer coat was applied over the chalks. (?)
Regardless, you should have no problem painting over what you have. If there is still some residue chalk left behind, it may mix with your paint (if you are brushing) and muddy it up a bit. If you are airbrushing it, it will no doubt just bury any residual chalks left behind.
Structures aren't nearly as critical as engines or freight cars as residual finishes can easily be blended in as weathering without being offensive.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
I'm removing pastel chalk weathering from an engine house (plastic) and want to paint. No seal coat was applied but can you paint over (with Acrylic) or do you need to prepare surface?
Thanks