door panel watershield for 50 coupe

[Wm Steed]

The brown paper type vapor barrier is sold under the brand name of Aqua Bar 30/30. It is available at any building material yard that sells plaster supplies or a good ceramic tile suppy warehose. I doubt if Lowes or Home Depot will carry it.
Most modern cars, ie; anything built since the 1960's usually have either clear or black plastic sheeting attached to the door between the upholstery pad and the door.

The water barrier will do to three things, seals out water from entering into the back of the uphostery, seals out drafts via the door/window and tightens the door up making them sound much quieter.  I always attach the sheeting with duct take. I use a piece of sheeting big enough to cover all of the openings in the door.

I would caution against using varnish on the back side of the upholstery panel. The varnish would have a tendency to trap moisture within the panel, not allowing the moisture to "breath out"...Bill

[elmo]

another tip to help water proof the doorpanel is to paint the inside of it it with clear varnish befor installing it

[David Pollock]

The watershield you refer to was originally a brown paper impregnated with tar very similar to the vapour barriers used in houses of that era.  It was fastened to the door before the upholstery panel was installed. The fastening was some sort of adhesive supplemented with tape similar to masking tape.

This material was usually discarded when a door was opened up.  Any modern vapour proof material will work, including plastic.

[brucepine]

I have used clear or black visquene (sp)  plastic sheeting, which is available at most hardware or garden supply stores.  Buy the heavy duty grade.  It is attached to the door metal so as to shield the door panel from water damage. 

[Edwin K.]

I'm reupholstering the door panels on my P-20 coupe. I am missing the material the repair manual calls watershield. I need to know a source for it. Also, does it attach to the back of the cardboard door panel or to the metal of the door? Thanks for any help.