I'm about to start installing my scenery backdrop hardboard (Masonite) on wooden frames that I've attached to the walls of my train room. I'm using the method described by Jeff Wilson in his Basic Model Railroad Benchwork. I have seen several references on how to seal the hardboard from moisture absorption. One reference used varnish to seal both sides of the hardboard, others do nothing to seal the surfaces. Others prime only the front side that will be painted with scenery. My plan was to seal the rear surface (against the wall) with one coat of a good quality acrylic latex primer and do the front surface with two coats of the same primer to seal the surface from moisture and to kill the brown hardboard color. I plan to do the priming before I install the hardboard panels on the wall. In your experience, is there a better way? I'm using the hardboard for the backdrop panels because of cost and their ready availability. The train room is heated and air conditioned.
Thanks for your help,
Bob
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
I used the walls of the room as my backdrop but used 1/8" Masonite hardboard to cove the corners. To do this easily, you need to start with the application of the drywall. I used 1/2" drywall, applied vertically (an amateur like me can do a better finishing job utilising the tapered edges available on the long side). For at least one stud spacing on each side of the room corners, both inside and outside corners, I used 3/8" drywall. For the corners (and only from the top of the benchwork to the ceiling), I cut a piece of Masonite a few inches narrower than the combined widths of the 3/8" drywall on either side of the corner. Place one vertical edge of the Masonite against the protruding edge of the 1/2" drywall on one side of the corner, then, using your hand, press the centre of the Masonite towards the corner - the free edge of the Masonite should slide along the face of the 1/2" drywall on the other wall, then drop into place when it reaches the 3/8" material, effectively "trapping" the now-curved sheet of hardboard. If it's too long to do this, remove additional material from one side edge of the Masonite - this stuff will curve down to about an 8" radius without breaking, although a wider radius looks better, as it's less likely to cast shadows. Ideally, the back side of the Masonite at both edges should lie flat against the 3/8" drywall for at least 1" in from the edge. While the tension of the curved hardboard will hold it in place, I drilled and countersank, then applied regular drywall screws along both edges. This was followed with mud and drywall tape, as you would for any drywall joint. I then painted the "sky" using a roller, working it horizontally to blend the colours.
You can use the same 1/2" -3/8" drywall set-up to do outside corners too: the main difference is that the piece of hardboard should be longer than the combined widths of the 3/8" board on either side of the corner, forming a bulge as it covers the corner.
I didn't seal the back of the hardboard, and the front was painted with interior latex house paint. In the 16 or so years that it's been in place, (in an unheated/non-air conditioned/well-insulated basement) I've had no problems with cracks, swelling, bulging, or anything else. Combined with fluorescent lights, the corners almost "disappear".
Wayne
Wayne,
Thanks for the info. Your backdrop looks great. Do you know what the approximate radius of curvature was for your inside corners. I did a test fitting of my hardboard on my supporting frame and thought that a curve radius of 22" to 24" would give a nice transition around the inside corner without sacrificing too much of the space in front of the backdrop for track and scenery.
Thanks, Bob. The 3/8" drywall in most areas extends about 20"-24" from both sides of the corners, but the actual curve starts much closer to the corner - I'd put it at about a 15" radius. I think that it might look a bit better if it was a little broader curve, but it's certainly less distracting than a straight corner. In the photo below, the mid-point of the curve is roughly above the last fence post to the right, near the edge where the two tracks converge.