A heat gun and a putty knife will get you the fastest stripping results.

+1 on the heat gun but test them for lead first and make sure you are wearing the proper PPE respirator protectors.

I don't think they really need to be vented if you make sure they are capillary broken on the bottom and keep the moisture out of it.

Thanks for sharing. I had the columns stripped by a local stripping company. Unfortunately, it seens that splits in the columns appeared afterwards. A heat gun would have been better.

Wooden base

Wooden base sitting on the painted aluminum plinth. Top capital on right.

Underside of aluminum plinth

The contractor did bore holes at the top if the columns in order to vent the columns. I also used aluminum plinths to sit the bases and columns upon to prevent rot from water. The plinths and bases also had holes in the center.