Laminating card sheets

[johnco]

I'm in the process of constructing several railway buildings in 4mm to 1ft by laminating 2 or 3 layers of card with PVA (card sourced from cereal packets) then covered with brick building paper.
The results looked very satisfactory.
Two days later the whole lot have developed a significant warp which has rendered them useless.
Could this be an effect caused by the recent high temperatures or the choice of adhesive?
Any suggestions would be welcomed.
Thanks

[Bufferstop]

The heat will certainly have accelerated any tendency to curl. I have my reservations about cereal packet card, it has been destabilised by printing on one side, so is going to have its own inbuilt curl factor which needs to be overcome. The simplest way being to laminate two sheets face to face, then to maintain stability always add laminations to both sides at once. If you regard the stabilized two sheet combination as the core, conventional wisdom (or what everybody says you should do) is to add a balancing sheet to the other side, so if you add brick paper to the outer face you need to add a similar weight of paper to the inside. Seems to work and is also a first step to adding interior detail.

[johnco]

Thanks for your observations.
I'm sourcing some 1mm and 2mm grey card for my next attempt.

[stuartp]

Try 2" double sided tape too (carpet tape). That avoids the water content of PVA.