You may find using a blunt knife it can be removed. Certainly worth breaking the crust to allow solvent to soften the paint first. Apply using a towel, dab a bit on and hold the towel in place for 30 to 60 secs, to stop evaporation. Check for transfer and use a clean area for each application. Avoid over application the cloth maybe bonded and it can still leave a dust line or 'watermark'