Terrain boards - construction advice needed (warping!) - edit: problem solved?

[Charlie_]

If you are leaning 2'x4' boards against a wall - and triply so if the short edge is on the floor - I can pretty much guarantee warpage of just about any wood product as a natural reaction to the forces of gravity.

Ok, guess I'll be lying any new ones flat under the bed!

One thought, what sort of wood are you using for your battens?  If it is soft wood like pine or its 'modern' substitute 'white wood' (whatever that is), you are going to get warping.  I always use hardwoods which are more expensive but much less likely to warp.  I also both glue and screw my battens - doing my best to countersink the screws so they aren't sticking up above the flat surface.  Then some wood putty, some drying time, and some judicious sanding.  Yes, a lot of work but if you want a quality result, it takes time.

Ah yes, it is pine. Both glue and counter-sunk screws. Switching to hardwood is a very good idea....
However I can't seem to find anywhere supplying hardwood of the right thickness  (20mm, to match the blue foam boards). Not at B&Q or any other DIY superstores, not at builders merchants.... I can get 20x20 pine stripwood (which is what I use), and I've found 20x10 hardwood stripwood. But not 20x20 hardwood.
I guess I'd have to go to a a timber merchant to get this....

One other thing to bear in mind is that the warp might have been introduced pre purchase.

Yes it's a good point, I always check the sheets and the stripwood when I buy it. I find 50% of the time the stripwood is seriously bowed, and I'm always careful to select ones which seem to have no bow.

Just a single sheet/layer should do it with watered down 'glue of your choice'.

I'm gonna give it a go this weekend!

[Hu Rhu]

If its any help I use 12mm MDF with extruded foam glued on top with Gorilla wood glue.  I place a few heavy books or piles of wargaming magazines on top and have never had any warping. I store them both vertically and horizontally depending on how the level the terrain I have modelled on. I have never felt the need to add battens or edging but do give the foam a couple of coats of watered down wood filler as both a sealing base and some added protection before painting.

[Charlie_]

Hmm, I may have cured the warping issue?

You could try and glue some single sheet newspaper to the underside of the boards with watered down pva/wood glue to help counteract the warping.

I tried this. I glued newspaper underneath with PVA, let it dry, then put another coat on PVA on the top just for the hell of it. I then weighted the board down with some SERIOUS weight.... I weighted the whole board first for 24 hours or so, then did it again just on the two offending corners that are warped up, and left LOTS of heavy hardback books and a full toolbox there for about 48 hours total.

And it seems to have worked rather well! The warping on the board is now at a minimum, and it doesn't rock back and forth like it did before. It's not absolutely perfect, but it certainly is absolutely usable , much much better than before. Comparing it now to the other three 2x4 boards I have confirms this.

So, problem solved? Let's hope so. It will be interesting to see if it stays like this or not. I'll definitely be storing them flat under the bed from now on just in case.

I don't know whether it's the pva / newspaper combo, or just the weights. I'm tempted to say both of them together. I'm trying it on the next board now WITHOUT the glue and newspaper, simply because I haven't got any paper to hand. I'm gonna leave it weighed down, undisturbed, for 48 hours minimum, and see how it fares. If that doesn't do it, I'll add glue and try again.

There is light at the end of the tunnel! 

Thanks for all the help guys. I think we can say we've learnt this isn't an issue with one magic answer, but there are lots possible solutions worth trying. Please feel free to continue discussing this issue on this thread, it's always worthwhile info.

[OSHIROmodels]

Glad it’s on the mend. It’ll probably still undo the original bend for a bit as the pva has a tendency to dry on the surface first but not fully underneath. It can take a while for it to completely cure and it’s shrinking (albeit not very much) all the time.

Don’t do anymore to the one you’ve done for a good while and see what happens.