I am refurbishing an old large house. I want to strip back 100 years of paint on ornate skirtings etc, and then stain/varnish them as when new. I have used caustic soda in solution to strip back paint on smaller items in a barrel very successfully (stair rails, etc). If I make a shallow, timber framed container to accomodate lengths of up to 18 feet, what material can I safely use to line the frame; e.g. can I use polyethylene sheeting like in standard tarpaulin, or non-woven polypropylene. Any tips regarding pitfalls of using Sodium Hydroxide. e.g. solution strength; length of time submerged; how to ensure neutralisation. etc.

Thanks so much.