Yes, as long as you gesso it first. Gesso is a white acrylic paint you can get at any craft or art store. Without Gesso, the cardboard will absorb much more of the oil paint and will peel and crack faster. Gessoing will save you money on oil paint and touch-ups! To gesso, take a large brush and a dish of water. Paint the cardboard with a thin layer of the gesso, thinning it out with the water. Make sure all your strokes go in one direction. After you've done one thin coat, let it dry. Then do another one, only with the strokes in the other direction. After that layer has dried, do a last coat in the original stroke direction. Remember to let the gesso dry completely before starting to paint with oil paints!
Varnish preserves wood better than paint.
Paint can be applied over varnish, but it needs to be a compatible type of paint for the type of varnish, and the surface needs to be prepared by removing loose material, dirt and sanding. If it is not a compatible paint the surface needs to be etch primed. Contact a local paint supplier for advice.
You can't without destroying the cardboard.
# Sand it # Apply primer # Paint it # Apply varnish
Use paint thinner .
Varnish preserves wood better than paint.
Paint can be applied over varnish, but it needs to be a compatible type of paint for the type of varnish, and the surface needs to be prepared by removing loose material, dirt and sanding. If it is not a compatible paint the surface needs to be etch primed. Contact a local paint supplier for advice.
You need a Varnish with UV inhibitors.
Yes, acrylic paint will stick to white cardboard.
No, they will separate.
Elias Singer has written: 'Fundamentals of paint, varnish, and lacquer technology' -- subject(s): Lacquer and lacquering, Paint, Varnish and varnishing
You can't without destroying the cardboard.
Usually yes. You'd be advised to use a water based varnish, and rough up the paint a little before coating.
That is not generally recommended.
That depends if the paint is non toxic or toxic
Sometimes wood needs to be re varnished or restrained. To remove old varnish, you can use either a paint stripper or sand off the old varnish.
# Sand it # Apply primer # Paint it # Apply varnish