What I am using on my foam board backdrop is gummed kraft tape, the brown stuff everybody used to use for packing, spackle over and works great, I use regular masking on the back (the side that doesn't get seen).
Thanks for all the further replies and tips. I think I have my panels down very securely with the drywall screws, but I never thought about some floor joist glue behind them on the studs. Too late now, but I think I may just go along and run a bead of this down the back of every stud where it meets the panel...maybe enough will get in to make a bit more of a bond.
I tested the panels and screws on a scrap piece and it takes a mightly pull to get the panel to rip off. Even though countersunk with small head drywall screws, the screwing action creates a dimple of masonite driven into the stud rather than cutting through it. This seems stronger than I would have thought.
I was able to make a big cove corner around inside a six-foot end way. It worked out very smoothly.
I'll put up some inprogress pictures when I have a minute. Family is away shopping for the weekend so I haven't a minute to loose in the layout room.....you know how it is.
My background [Masonite] panels are joined together by a frame they fit into, so the joints are visible but it doesn't bother me as I don't really notice them. The panels are hand painted scenes, so I wanted them to be removable so I could take them to my workbench to work on them. As scenery has evolved over time, so has the painting on the panels. This would not have been practical if the panels were permanently mounted. I think coved corners are more important than invisible joints.
doctorwayneIf you go with wallpaper paste to attach long sections of backdrop, you can "book" it just like wallpaper to make handling much easier. After the paste has been applied, simply fold it (without creasing, of course) over itself in an easy-to-handle length (4' or 5' would probably work well for a horizontal application), placing the pasted faces together accordion-style. Wayne
If you go with wallpaper paste to attach long sections of backdrop, you can "book" it just like wallpaper to make handling much easier. After the paste has been applied, simply fold it (without creasing, of course) over itself in an easy-to-handle length (4' or 5' would probably work well for a horizontal application), placing the pasted faces together accordion-style.
Wayne
Or you could have four or five model railroaders tripping over each other each shouting out orders on a better way to do it,
Another trick not mentioned is to use a damp (not wet) sponge to remove putty knife marks. Since wallboard compound is water soluable the damp sponge will disolve small ridges from the knife and not require sanding at all. It all depends on how good you are with the blade!
Bob
Life is what happens while you are making other plans!
Nobody has mentioned sanding screen yet. This is a hardware-store item that's sold over in the drywall aisle. It's basically just a steel mesh sheet. It is used for smoothing down drywall compound because the mesh will smooth down the rough parts but will not immediately fill up with the dust, like sandpaper will. I don't do all that much drywall myself, but the piece I have has lasted me many years.
I've also discovered that sanding screen is great for sanding down Hydrocal castings. It's much quicker than sandpaper, and you can get rid of lumps and bumps on the back or trim the edges to get a perfect fit.
It takes an iron man to play with a toy iron horse.
First off if you want nice tight seams when using Masonite a trick a finished carpenter showed me was to not cut the edge square but in an 30 degree angle this way when you slide to tow pieces together you don't have a butt joint but a mitered joint with is much finer and will be less of a problem. How ever if your using drywall compound to finish off the seams you may not want to bother with the miter cuts. You will most definitely need to rough up the surface if you don't u can guarantee it will crack I would use either 60 or 80 grit on the seams to give the drywall compound something to grab to. Befroe you do anything when you attach the Masonite to the drywall in the room if you are not making free standing back drops be sure to use construction adhesive and not just drywall screws.that little step will save u a lot of heartache down the road. They also make a countersunk drill bit for drywall screws so the screw heads will sit just below the surface of the Masonite making it easier to hide the screw heads.
When it comes to putting up your backdrops, what we have used several times on different friends layouts has been good old wall paper paste.The new stuff they have out is far superior then the old stuff that used to dry out and resulting in peeling wall paper. It will hold the backdrop but still give you some work time before it sets up to shift it into place and get out any air bubbles. One thing that is a must is don't try and do it yourself. extra hands can be very very valuable especially if your working with longs pieces.
We all got a hands on lesson one Saturday from a guys wife. seems that women have the wallpaper hanging gene in their DNA, it also helped that she was an interior designer, she showed us how to seam tow pieces together and make it look like one piece and how important it was to get out any trapped air bubbles with a small roller u can get in any home center. One thing i can say is that if you plan on using any type of spray glue wear the proper respirator as that stuff is really really nasty.
I used the mesh tape with vinyl spackling compound. The theory is that the vinyl will flex a little instead of becoming brittle. Two years old and I don't have a single crack. I didn't worry about sanding it too smooth. Fairly smooth was acceptable to me for this application.
Cisco Kid I have pretty much decided to simply put drywall compound over the seams with no drywall tape. My seams are very very tight. I think I trust the drywall compound to stay on the masonite even more than I trust packing tape....
I have pretty much decided to simply put drywall compound over the seams with no drywall tape. My seams are very very tight. I think I trust the drywall compound to stay on the masonite even more than I trust packing tape....
Use drywall tape. If the masonite expands or contracts slightly with heat/humidty, the drywall compound will NOT expand with it and the backdrop WILL crack.
At my club we use masonite backdrops with the seams dressed with drywall compound. What we've been doing on the joints is to use fiberglass tape, smear some epoxy on it and then mud over it. So far none of the joints treated this way have shown ANY signs of movement or cracking. Overkill is not necessarily a bad thing if you want to guarantee that it will hold up.
Chris van der Heide
My Algoma Central Railway Modeling Blog
Another option to consider is lining paper. The heavier grades can be used over panelling to hide the grooves between "boards".
Thanks very much for the info, gentlemen.
Yes, I am going out to get some web-type drywall tape now. I agree with the idea that plastic packing tape will not last forever. The fellow over in the O gauge forum elsewhere has been lucky, I think. But it has been only three years since he attached it.
I really couldn't avoid the 5 seams I have to deal with. The masonite panels only come in 8 foot lengths and I have 6 or so of them to cover with the 12 foot backdrops.
However, I do not need splines as I was lucky enough to be able to either hit a stud with the seam, or add a stud right flush with any seam that fell between the 16" ones. Those babies are not moving easily, let me assure you. I have laced the seam with six screws on either side of the 24 inch vertical and flush is the word. I was also lucky to have the room so square with the panels that there is actually no gaps at the seams whatsoever......or microscopic to my eyes at least.
Just now sanded the seams down.
I completely agree with taking my time and making wide "mudding" over these seams. Thanks for firming up my decisions on this.....now off to the hardware.
Once this is all done I will post some pictures of the stages of the layout expansion.
Cisco:
I have to agree strongly with Brent that you need some sort of support web over the joints or they will crack and you will end up with unsightly lines showing on your backdrop. Simply putting drywall mud into the seam is asking for cracking later. I've done enough drywall patching in my career to assure you that this will happen.
Joe
Cisco, you really need to do this right or you will regret it. Backdrops will magnify any imperfections in the surface underneath. Be patient.
I will tell you how I joined my masonite pieces together. You may or may not apply the info to your situation.
First I put a six inch wide Masonite splice on the back to reinforce the seams. Next I filled all cracks with Dap to make them level with the face of the board. I then used a web type drywall tape, I think it is plastic or nylon over the seam. Then you start applying mud in layers going wider between coats. I would go at least a foot on either side. This will take a few days so don't hurry. Sand lightly between coats.
This is the most important step to having invisible seams. While sanding, close your eyes and feel for rough spots. If you can feel them with your fingers with your eyes closed you will most certainly see them when painted or covered.
Go ahead and get as close as you like. You won't see a seam.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
Cisco KidI have pretty much decided to simply put drywall compound over the seams with no drywall tape. My seams are very very tight. I think I trust the drywall compound to stay on the masonite even more than I trust packing tape....
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Cisco KidMy seams are very very tight.
Although the seams seem tight, what is the masonite attached to? I believe that the attachment structure will move over time as it expands and contracts. As that structure moves, I think the seams will try to open up.
I don't know the cure for this, other to suggest that it might have been better to have used a continuous piece as long as possible rather than the panels.
Packing tape will not adhere to the masonite and remain there. It will turn loose after some time passes.
Float over the joint with compound, getting it as smooth as you can. Let it dry at least 24 hours, then lightly sand it to remove any imperfections.
Don Z.
Research; it's not just for geeks.
(sorry to go on about this, but I am just about ready to commit my backdrops to the wall, and they are expensive so I am being very cautious...having ruined some cheaper ones on an earlier layout)
I found a thread in the O-gauge (OGR) forum site exactly on this topic. I'm still waiting for my membership to be confirmed so I can directly quiz users there.
However, wanted to put up a thread topic here in my favorite forum on this.
Has anyone here ever used just 3M clear packing tape on masonite panels to smooth over the seams? I am still concerned about just using drywall compound and tape for a couple of reasons.....in the past my drywall seams look crappy, and I am not sure about the compound sticking for long periods to something as shiny as masonite.