I made roofs for some of my structures with 0.040 sheet styrene from Evergreen and painted them with rattle can paint. Several have warped, some more than others but all will need to be replaced.
Has anyone else had this problem? What does one do to prevent warping? Is there a better material to use?
Roger,
What glue did you use to bond them down?
Did you prime the styrene first?
I’ve had roof where I used something that had a bit much solvent in it to bond it to foamcore or something else underneath. These ended up warping, but it didn’t happen right away. Not sure of the process, other than maybe the bond let’s lose unevenly. I thi nk it was Goo that I used, probably NOT following labels directions.
While most rattle can paint on styrene will not warp it, heavy coats might.
I tend to make my roofs out of sheet styrene, covering them with paper-printed shingles or corrugated roofings. For large expanses, I tend to use the black formcore. Mostly I use 3M 77 spray adhesive and have had no issues.
Another reason for warping just came to me. Are you roofs supported underneath well? .040" seems stiff enough, but it will sag if not properly supported. Maybe that’s the issue instead of actual warping?
I have had styrene “warp” when I tried using adhesive to bull it into position. Unfortunately it did not warp the way I hoped. And sometimes styrene sheet warps when sprayed with solvent based paint (in addition to crazing the surface).
I have heard of, but not experienced, styrene warp when laminating one sheet to another - presumably due to the cement but perhaps also due to differences in the chemical makeup of the styrene sheets.
And I have certainly seen the hot sun do some horrid things to plastic models which were left in a hot car on a sunny day. I particularly remember a hilariously distorted plastic Mantua tender body …
I also once attached a styrene flatcar deck to a styrene flatcar body using Walthers Goo, forgetting the advice given to MR to drill a few holes in the body to allow the gasses that Goo gives off to escape. Result: odd looking bulges on the supposedly flat deck, that could not be resolved even by slicing into the styrene along the scribed lines. Some guys have had similar experiences when Goo-ing in the weight into an otherwise closed tank car body. I remember posting about that experience on these forums and receiving a mocklingly exasperated reply from the late Andy Sperandeo along the lines of “you didn’t listen to us, did you?” [:$]
Dave Nelson
Mike,
No glue to bond them. They just fit down inside the walls resting on ridges all around.
No, I did not prime the styrene first. And that may, indeed, be the problem. But what to prime them with short of dragging out my airbrush and using some acrylic paint?
These are flat commercial building roofs so bonding shingles, corrugated metal, etc. would not be appropriate.
I don’t think I put on heavy coats but, as I noted above, the paint may well be the problem.
The roofs are not supported underneath but the two worst ones are only 3" x less than 5". I have one that is about 18" long but only 5+" wide that I strengthened lengthwise with strip wood glued to the underside. It warped 90 degrees from the lengthwise center line.
Dave,
As noted in my response to Mike, no adhesive was used in securing the roofs. I used contact cement to bond the strip wood to the long roof and have had no lengthwise problems.
Then have not been in hot sun. My layout is in a lower level room with pretty constant temperatures in the mid to high sixties and the sum coming in the windows doesn’t reach the dayout.
‘‘braceing’’ the right amount at the right place.
depending on the size of the roof,could be sagging as mutch as warping
040" sheet styrene will warp or sag of its own accord, and so will the .060" styrene that I use.
This not yet finished freighthouse has a sub-roof and unseen back wall of .060" sheet styrene:
Both the structure…
…and its removeable roof are braced with the same material:
Likewise for this kitbashed Walthers warehouse:
…and this one, made with DPM modular walls. The flat roof is supported by a grid of 1" on-edge strips of .060" material cut from the same 4’x8’ sheet:
This one is built entirely of .060" sheet, exterior and bracing:
Wayne
I’ve used Zinser 1-2-3 in the spary can to prime pink foam so I can spray can it for scenery. Foam is much more sensitive than styrene, so I’d think a light coat of 1-2-3 would solve it if it’s due to paint.
Echoing Wayne’s and others comments on bracing, a 3"x5" roof should have at least one brace between the walls.
Krylon and Rustoleum both make plastic compatable spray paint. Krylon calls theirs Fusion.I do not remember what Rustoleum calls theirs.
I do what doctorwayne does in most cases. However, if you want to detail the interior you can detail the roof trusses too:
Dave
I have had styrene warp when only one side was painted. Painting both sides seems to prevent this problem.
Mark Vinski
The more I read this thread, the more confused and depressed I become.
I am in the middle of a relatively large scratch build, and the last thing that I want to hear about is warped styrene sheet.
How soon is this happening? During construction? Shortly after? Long after?
Is this on walls? Roofs? Both?
What’s the cause? Glue? Paint? Lamination?
So many questions, so few answers.
Rich
What brand spray paint did you use?
When Floquil disappaered, I started checking out spray can paint to collect and air brush. I found solvets or propellants in some spray brands were not plastic friendly and some were too quick drying to use in my air brush. They set up and gummed it up something fierce. Even laquer thinner would not cut it in some cases.
I have had good luck with Rustoleum primers straight from the can. I stay away from those that claim to dry to the touch in 10 minutes, the solvents are too agressive.
You need to brace the stuff even more than wood.
I once bought a whole bunch of 4’ x 8’ sheets of 1/2" thick art foam board as backdrops and used a roller and latex paint to cover the sheets. The next morning, the sheets warped like crazy.
So, what is the problem here? Is it the paint?
Rich
Hi Rich.
To try to answer your questions:
“When is this happening?” That depends on the cause. If it is a paint or adhesive issue its going to happen as the solvents dry. If it is a lack of support the problem may not show itself for months or years. Keep in mind that you are not just bracing to support the weight of the roof. Temperature differences can cause warping if your lighting is heating up the top of the roof. Age will be a factor as the chemicals in the styrene dissipate.
“What causes the warping?” Paint could definitely be a factor. The easiest way to deal with that is to paint both sides with equal coverage. However, I think that proper bracing is the most important issue. It needs to run vertically like roof trusses, and it should run horizontally. The best place for the horizontal bracing is along the eaves just inside where the roof will sit on the walls. The vertical bracing can be simple 'V’s just like Wayne has used.
“Is this on walls, roof, both?” Any flat surface should be braced. We have already discussed roofs. The easiest way to brace the bottom of a wall is to install a floor or at least a partial floor along the walls. External porches or loading docks, or even sidewalks can also help keep the walls straight. At the top of the walls .040" or .060" x 1" styrene strips glued perpendicular to the walls will work well.
The roof on the Coors mansion already has a fair amount of bracing just by virtue of the design itself. All those ridges and valleys serve to stiffen the structure considerably. However, I would still use some fairly substantial horizontal bracing along the edges of the roof just inside the walls. Something like the strips used at the tops of the walls would work. Alternately, you could install .040" or .060" ceilings if you are going to detail the inside. Vertical bracing should be done at least in the larger areas as well.
Dave
Edit:
Dave, thanks for that reply. So, you attribute the warping or sagging to lack of bracing. I will add the V-shaped supports to the underside of the roof on the mansion. As far as wall bracing, last night, I constructed a styrene base and added styrene strips onto the base to lend bracing to the walls of the mansion.
Rich
If you think about it, a prototype roof has a “brace” every 16-24" under it. Model one should have braces every 3-4" or at least no more than 3-4" unsupported.
Solvent paints and glues can warp plastic (I’ve had really bad results with sheet styrene and Pliobond).
I used Plastruct Plastic Weld on my scratch build. I hope that provides good results long term.
Rich