6 panel varnished doors. Can I sand and paint? Or must I strip them?

If there is no chipping, etc... you can just rough them up with sand paper and paint them ..... but....be sure and mask off very well... and use a tack cloth to remove any residual saw dust

Hi Lynne, you should be able to sand and paint them. Sand lightly, then use paint on a stainblocker such as Kilz or Zinsser as a primer before you paint the color of your choice.

Sand and paint

Absolutely, sand then smooth, prime to ensure even coating then paint

Removing finish by sanding: Good for paint, acrylic, varnish, lacquer, shellac.

Just sand lightly, prime and paint. You must prime. Or you can use chalk paint and do no prep except to clean them of any grease. Chalk paint finished with wax is actually amazingly strong and "clean-able."

You can sand, then be sure to use a primer like Zinseer B-I-N to prevent the stain from coming through the paint, I like to use an epoxy paint since its made for weather.