advice wanted on board warping

[dexter]

 I was planning to make a series of 12inch by 12 inch boards .
i built this one  during Jan and Feb

played with it in March and early April then put it in a cardboard box. GOT it out this week and the board has warped. This means it warped approx 8 weeks after it was made

Does anyone have any suggestions how i can stop future boards warping?

The board is 5mm thick made up of 3 layers of wood pressed together. The surface was made using filler and painted with acrylic

thanks
Dexter

[Ramshackle_Curtis]

Hmm, there really is no sure fire way to stop warping Im afraid. Maybe use steel sheet next time? Ha, no but seriously I used to work for Aardman animations (wallace and grommit) and they used to get serious issues with stuff warping. Imagine that with animation even a few mm makes all the difference. They used to do things like leave the lights blazing overnight, or have warm up periods, as the models and even the camera fittings would change size due to heat.

I feel for you buddy, but even sheet steel can be made to warp.

I tend to try to work with the warping. Plan for it in advance, either by making smaller based things or by giving your scenic elements time to properly cure before applying them to a board.

[Fitz]

As a first step, make sure your boards are thoroughly sealed on both sides and all edges before you start working on them. If you can keep moisture out it will go a long way to keeping them dimensionally stable.

Try, wherever possible, to use non-shrinking paints and glues for terrain work, especially if you're laying down large areas of flock. If you have to paint or glue all or most of the board, do the other side as well so that shrinkage is equal on both surfaces.

Store the finished boards somewhere dry and not too warm. It might be worth investing in some sealable plastic crates and some silica gel (you can get reuseable silica packs that can be dried out in the oven when they become saturated).

[FramFramson]

Ha, no but seriously I used to work for Aardman animations (wallace and grommit)

Well ain't that a thing. The wife and I were just re-watching the three old shorts last night. 

[Ramshackle_Curtis]

Well ain't that a thing. The wife and I were just re-watching the three old shorts last night. 

I only worked on Chicken Run.

[Funghy-Fipps]

Early last year I started using 3mm Palight foamed PVC as basing for all my scenery projects and have since never had any problems whatsoever with warping (and remember: it's only 3mm thick!).  Using thicker MDFs and suchlike in the past I too have had the occasional accident.  Additionally you can cut foamed PVC with a Stanley (I haven't used my Jigsaw since!) and even use it as a superior substitute to foamcore!  I highly recommend it and source mine from Antenocitis Workshop here. 

[traveller]

It sounds like you are using thin plywood. The only way to avoid warping is to glue/nail woodem battens on the bottom side. I make a frame around my plywood boards and then put another couple of wooden battens across. Good luck!

[Centaur_Seducer]

I seriously think its a question of material, I'm afraid

Plywood is great in many ways, one of its main advantages is the elacisity, however, this also means that it'll warp really badly unless you bolt it to a frame or some other surface.
I use it for minor repairs on the boat when I'm on the go. It really eats up the water and is a perfect plug until you can get the boat into a dry dock or lift it for major repairs

[Argonor]

It sounds like you are using thin plywood. The only way to avoid warping is to glue/nail woodem battens on the bottom side. I make a frame around my plywood boards and then put another couple of wooden battens across. Good luck!

Exactly what I've been told. Chipboard, plywood, MDF - all need stabilizers if you want to completely prevent warping.

[Scout_II]

Sort of depends on what caused the warping.

Since this happened after completion - chances are they warped because moisture was absorbed (probably from the air) that warped the base material.

The solution is to seal all sides of the base during construction.  You find the same problems with wood trim and siding on houses - if you don't paint the back side, it will warp.  I always give everything a good coating of paint before I get started with the finishing details.  Remember to use paint though and not just a primer.  Most primers are not designed to seal (though for terrain - you can get lacquer based primers by the gallon if you prefer).

The other common cause is tension.  Sort of like stringing a bow.  Most of the stuff we use to make terrain shrinks as it dries.  Since we usually only put that on one side of the terrain - it pulls the base in that one direction.  In order to avoid this - you have to use a base material that is stiffer than the pull of whatever you put on top of it (or minimize the pull).  Wood, plywood and MDF is actually stiffer than most of the alternatives (cellular PVC, plastics, foam) - so as long as you seal them...they should stay put.

To minimize the pull - use thinner coats of whatever...glue, paint, terrain gels...  It also helps to work in patches as opposed to all at once.  If you cover a board from side to side with something like PVA glue, as it dries it will create a significant force pulling up at the edges.  However, if you work in quarters at a time - each dried section will pull at its own area.

Certain materials also have internal stresses (extruded foam for example).  If you carve into the top of these, you can see the internal tension cause the board to warp downward.  It is most apparent in the direction of the grain with extruded materials.

[snitcythedog]

I seal the living hell out of my bases to stop it.  First a coat of dull coat on both sides.  Then after I add my basing material I either do a coat of wood glue or a coat of superglue to seal the top.  The bottom gets covered in felt attached with a spray adhesive (Super 77 from Scotch).  I end up with an airtight seal both top and bottom.  Humidity here can range from 2% to 90% depending on the time of the year so warping can be a real issue. Hope my two cents helps.
Snitchy sends.

[former user]

wood is not inert to moisture actvity
I presume the boards warped upwards, towards the surface
only thing you can do is glue thin cardboard on the underside, it will bend the wood back

otherwise - dont use wood panels

[inkwell]

For a 12 by 12 I would use ceramic floor tile.Seiously cheap-NEVER warps.I base all my buildings on ceramic and I love it!

[dexter]

aren t ceramic floor tiles fragile though? whenever i see them in DIY stores there are always a number which are cracked or have their corners chipped off.

dex

[Cory]

Ceramic can chip and does not hold white glue well, but I have seen it used successfully.

One option to consider is to use a frame to prevent warping. One of our local gamers cut one inch wide strips of 3/4' plywood and attached them to the back of his mdf boards, the grain of the plywood layers perpendicular to the board. Fifty or so boards with no warping what so ever.

Like this.