I have two different MR books addressing backdrop finishing work at the joints of hardboard. One mentions using spackle, the other: the full drywall application with tape. Pros and cons for each please. I get the impression the drywall mud with tape is more resistant to cracking? I've done plenty of spackling in my day but never done any drywall work.
Thanks
Andy
--------------------------------------------------------------------------------------------
Milwaukee native modeling the Milwaukee Road in 1950's Milwaukee.
https://www.flickr.com/photos/196857529@N03/
Both are susceptible to shrinkage cracking if applied too thick.
I'd go with the dry wall mud and tape, because I've done it many times before, and that's what I used to prepare the wall for my back drop, but, I used drywall and not hardboard.
I would think the drywall method would hide the seams better.
When I think of spackle, I think of filling small nail holes, and divets, and misc imperfections before painting, and not hiding or covering a joint in a wall system.
Just my thoughts,
Mike.
My You Tube
I have only ever used 'exterior' spackle, but only to clean up weathered and badly pitted door trim or sills, or the ends of large beams that have suffered under the weather for a few years. Spackle designed for exterior repairs dries very hard, and it's difficult to sand. So, troweling/smoothing well is important at the outset.
Taping and mudding takes longer, but you might find it more easily handled and shaped.
If you have installed the hardboard already, ignore this post.
If you haven't, you might want to look at using .060 or .080 styrene sheets. In more populated areas they can be found in 4'X8' sheets. That's what I use. I cut them to height the long way, and have something just like a hardboard backdrop. At joints I add a 2-3" doubler in the back, glued on with Testor's gooey type model cement (stays wet long enough to work with on the larger pieces). After dry I fill the crack on the front with Squadron putty and sand smooth. I run a sanding sponge over the entire surface to add some tooth for the paint, wipe down with a damp cloth to remove the dust, then paint. Presto! Long smooth backdrop, (relatively) easily bent to even 5-6" corners if needed.
Mark P.
Website: http://www.thecbandqinwyoming.comVideos: https://www.youtube.com/user/mabrunton
The Milwaukee Road WarriorOne mentions using spackle, the other: the full drywall application with tape.
I suggest making up a little test panel and try both to see what works best for you. Embedding tape on the flat surface will make it more difficult to feather the edges. Drywall has tapered edges to compensate for that.
Something else to consider, since you are only doing small joints would be the Durham's Rock Hard water putty.
https://www.lowes.com/pd/Durham-s-64-fl-oz-Light-Yellow-Patching-and-Spackling-Compound/3143343
Just be sure to smooth it out as best you can as it is more difficult to sand than joint compound.
I use it for some casting work and it is ideal for making "paved" roads.
Good Luck, Ed
Yes, one of the Kalmbach books suggests covering the joint with mud without tape. So that's what I did and it cracked within weeks. I redid it 5 years ago with tape and mud and it hasn't cracked.
Simon
PruittIf you haven't, you might want to look at using .060 or .080 styrene sheets. In more populated areas they can be found in 4'X8' sheets.
Where could I find sheets like that? Would Home Depot or Menards have them?
York1 John
The thing to remember is that neither 'spackle' nor the better kind of 'joint mud' are plaster. They have been loaded with agents like the 'acrylic' additives used as bonding agents in concrete patching, and, in some cases, with composite filling material, to be able to bridge gaps with some elastic capability and better strength even when 'feathered out'.
The tape or mesh is there to further bridge the joint between large panels, so that mutual motion of one panel against the other isn't magnified into more shear or stress than the material can accommodate.
I personally think it's a really good idea to use some kind of tape between boards in a backdrop. The problem is that, unlike drywall sheets, the edges aren't tapered so that the taped joint can be 'full thickness' but the outer surface flat when prepared. Expect that even using something like Mylar as the 'tape' (which I don't recommend because mud generally won't stick to it well without careful compatible priming) you will see the joint as a slightly raised area even if you 'feather' carefully, and perhaps you'll see where the edges of the dutched section are.
I would also recommend that you think about adding a little separate binding agent to the 'spackle' you use, whatever it is, if you want a little more strength, or adding one of the available strengthening composites if you have the need, if you find problems with joints reappearing.
In the old days, an 'answer' to the joint issues (with ceilings) was to adhere a layer of material like fine canvas over the whole plaster and lath structure to form the final 'surface' for painting. In a sense, good wallpapering does the same thing. It might be desirable to dutch the seams of a flat backdrop, say of Masonite or Homasote, with thin paper soaked in a good spackle or mud, then put a whole backdrop painted on paper or other 'art material' over the work when you've sanded it smooth.
After priming and painting all 4 sides of my masonite backdrop panels, I install them with a 1/16th inch gap to allow for any expansion and then use drywall tape and mud, feathering the joint of course. I have not had any problems with cracking or appearence.
- Douglas
This is just an idea, and it may present obvious drawbacks to those more experienced in such things than I, but could you lightly hammer some wire mesh into either side of the gaps? If you can embed it, you'll only have a smear of compound to cover the gap and fill it, and the wire may act something like the tape. Or, use a surform file and file your own tapers, and then use mudded tape. Could work...?
York1 Pruitt If you haven't, you might want to look at using .060 or .080 styrene sheets. In more populated areas they can be found in 4'X8' sheets.
Pruitt If you haven't, you might want to look at using .060 or .080 styrene sheets. In more populated areas they can be found in 4'X8' sheets.
Mark P, I have been considering that. How does it attach to the benchwork, and is warpage or waviness a problem.
I did buy a 4x8 sheet from, I believe, Total Plastics
which is about 20 miles from me The rolled it into a tube, maybe 6-8" in diameter, so they could ship it, but that would increase the cost
Henry
COB Potomac & Northern
Shenandoah Valley
selectorcould you lightly hammer some wire mesh into either side of the gaps?
You can use mesh, but
1) it rusts. And the rust will bleed to the surface;
2) if you sand through to it, the spots will not only rust but bloom;
3) any loose tags of wire will be sharp
Note that the open-weave tape sold for joints can be thought of as essentially the plastic version of metal mesh.
I think you'd be forever trying to cut a consistent taper with a Surform, and the surface you raise on Masonite or Homasote will be rough (and I think relatively water-absorbent). You might get better results with something like an angle grinder equipped with an open disc pad. Be careful not to cut the taper so wide that what you use to sand the joint level 'dips' into the tapered section...
I would recommend using Plastic Wood, by DAP. Stronger than most other suggestions. Easy to use, with a putty knife. Been using the product, since the late 50's, when a similar chemical consistency came in tubes.
https://www.dap.com/dap-products-ph/plastic-wood-latex-all-purpose-wood-filler/
Take Care!
Frank
I'm going to be another voice against using masonite at all.
My choices:
Styrene as suggested above.
Aluminum coil stock.
or drywall.
Yes you can build a curved backdrop with drywall, we build curved walls all the time.....well they end up curved, but it takes some skill with the drywall mud.
For which we would use Durabond, not premixed drywall mud.
Despite whatever success people have had, drywall mud is not designed to stick to the smooth hard surface of masonite.
I'm in construction, and we don't use masonite for anything........
Sheldon
To clarify, I already have the hardboard in place. Approx 1/8" to 1/4" gaps between sheets.
I do have DAP plastic wood already; I had not considered using that. I read about styrene and considered that. Same with vinyl flooring. Decided on hardboard. I have also wondered about the slight "bump" that is inevitable with using drywall mud, but I'm guessing that can be sanded down like spackle or any other material.
I also have Elmer's Probond wood filler but I'm not sure how that would perform over time. I don't know how "elastic" it is. I've used it to fill gouges and smaller holes before but not a 4' tall gap.
ATLANTIC CENTRALDespite whatever success people have had, drywall mud is not designed to stick to the smooth hard surface of masonite.
Raises another question. Both books I've referred to at home (as well as some videos) talk about priming the hardboard with at least one if not two coats of latex primer. I wonder: if that is done *before* the gaps are sealed would the primer help the drywall mud (or spackle or wood filler) to better adhere to the previously smooth surface? Or would this make no difference in the long run?
The Milwaukee Road Warrior ATLANTIC CENTRAL Despite whatever success people have had, drywall mud is not designed to stick to the smooth hard surface of masonite. Raises another question. Both books I've referred to at home (as well as some videos) talk about priming the hardboard with at least one if not two coats of latex primer. I wonder: if that is done *before* the gaps are sealed would the primer help the drywall mud (or spackle or wood filler) to better adhere to the previously smooth surface? Or would this make no difference in the long run?
ATLANTIC CENTRAL Despite whatever success people have had, drywall mud is not designed to stick to the smooth hard surface of masonite.
Yes, painting it with good primer first will help considerably with the drywall mud.
Thanks Sheldon, I kinda figured that would be the case. Based on your info I'm at the point where I need to put latex primer on, so I will do that first and then come back to see if anyone else has shared anything on the mud vs spackle issue. Thanks to all above.
I'm assuming any latex-based primer will work fine.
York1 Pruitt If you haven't, you might want to look at using .060 or .080 styrene sheets. In more populated areas they can be found in 4'X8' sheets. Where could I find sheets like that? Would Home Depot or Menards have them?
Pruitt
Dap with mesh tape. Always prime the Dap. You won't see a joint even ten years later, go ahead get as close as you like.
When sanding it down close your eyes and feel with your fingers, if you can feel it you will see it.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
doctorwayneAfter 30 years, there is not one crack in any of the walls or at any of the corners, and the impression is of a seamless backdrop...
Wow. Well that is a ringing endorsement for the drywall method! Has anyone here had results this good with any method *other* than drywall mud? 10, 20, or 30 years without any cracks?
I'm planning to do this once and be done. This will be a permanent layout that -God willing- will last for decades. No plans to build and then tear it out in a decade and do something different.
BATMANDap with mesh tape. Always prime the Dap.
If I understand from your picture you primed on either side of the joints and then used DAP spackle to fill in? I'm not familiar with the mesh tape (I know what it is but is the tape you used from DAP as well or 3M or someone else?)
The Milwaukee Road Warrior BATMAN Dap with mesh tape. Always prime the Dap. If I understand from your picture you primed on either side of the joints and then used DAP spackle to fill in? I'm not familiar with the mesh tape (I know what it is but is the tape you used from DAP as well or 3M or someone else?)
BATMAN Dap with mesh tape. Always prime the Dap.
I filled the crack to level with Dap (no tape).
When that dried I put Fibatape over the areas where the crack was.
I then proceeded to layer Dap over the Fibatape until covered and sanded so you could not feel any ridges.
Once dry I primed the Dap overlapping onto the hardboard that is why it looks like that.
My good friend taught drywalling at the local trade school and told me that primer adds a lot of strength to the Dap. He was also the guy that told me about closing my eyes to feel how good your sanding job is.
Make sure you fill the crack to level before you add the Fibatape or it will likely crack.
I also added a 4" wide piece of hardboard on the back behind each crack with glue-gun glue.
BigDaddyMark P, I have been considering that. How does it attach to the benchwork, and is warpage or waviness a problem. I did buy a 4x8 sheet from, I believe, Total Plastics which is about 20 miles from me The rolled it into a tube, maybe 6-8" in diameter, so they could ship it, but that would increase the cost
I've got some that have moved with me several times plus sat in unconditioned storerooms, and never had an issue with warpage or waviness. They're basically immune to humidity and temperature changes (unless you go after them with a torch or soldering iron!).
Overmod selector could you lightly hammer some wire mesh into either side of the gaps? You can use mesh, but 1) it rusts. And the rust will bleed to the surface; 2) if you sand through to it, the spots will not only rust but bloom; 3) any loose tags of wire will be sharp Note that the open-weave tape sold for joints can be thought of as essentially the plastic version of metal mesh. I think you'd be forever trying to cut a consistent taper with a Surform, and the surface you raise on Masonite or Homasote will be rough (and I think relatively water-absorbent). You might get better results with something like an angle grinder equipped with an open disc pad. Be careful not to cut the taper so wide that what you use to sand the joint level 'dips' into the tapered section...
selector could you lightly hammer some wire mesh into either side of the gaps?
Ah, you are right. However, and in me own defence, I was thinking about some galvanized chicken wire, or even something finer. The cut ends would be a problem, though....
Thanks Brent, that is good info
NlI used mesh tape for some joints when drywalling my basement. The rest was done with paper tape. A number of the joints done with mesh cracked. None of the joints done with paper tape crack.
FWIW
Rio Grande. The Action Road - Focus 1977-1983
I have found that the mesh tape acts more like rebar in that it allows the Dap/mud to go right through it filling any voids that may be in behind it. This gives much-added strength. Nothing wrong with tape, just make sure every bit of it is firmly secured to the wall and not lifting off. With the mesh the Dap goes right through and fixes that problem.
Cracks again and come again and again....never ending story, and no good way to make cracks vanished from the backdrop.
All the layouts we see for the most have a cracks in a place of the backdrop or have had cracks in the backdrop joins
In fact contraction and expansion are normal for any wood structure or wood fiber stuff like masonite or MDF; these materials are not stable and are affected by wheather change or humidity in the air.
Put on these expandable materials some kind of rigid mud will give one day a crack; there are no issue about that and we can't do nothing against it
Plasterboard panels suffer from the same trouble in time unfortunately.
I use a different method for backdrop, seldom seen in US but in Europe some well know layouts use this technique and is quiet easy to use.
These layouts use a vinyl floor carpet hanged against the walls.
Vinyl floor carpet is easy to paint with latex or acrylics paints.
Course this need some clever trick to hang the vinyl floor to the walls and fix it or glue it on some supports because there is not a lot of background about it, but nothing really more difficult than the construction of a conventional backdrop
The vinyl backdrop can support any curves and there is no crack or join, this is a one piece backdrop since we hang a roll of vinyl floor along the walls of the layout room like a curtains
They are sold in lenght which can go to around 120' and with a width of around 3 to 5 feet sometimes more.
This is not really expensive beside a full wood structure backdrop
And eureka no more crack in the future which come back
No dust work to prepare and finish the backdrop seams,and no dust on a existing layout when you need to repair cracks.
Fast to make up when support are in place, a friend of mine used it for an HO layout in a room of around 36' by 12'; this was a one day job to hang and fix the vinyle roll all around the layout room
This layout is now more than 20 years old and no any trouble with the backdrop
Now living in Canada and on the way to extend my original layout I will use this kind of backdrop without any hesitations.