Its time to get away from flat poly styrene and add hills and hollows (so too speak) . Ive been told plaster of paris is too brittle, and to use plasterboard cement with netting , liquid glue added and when mixing it add coloured paint . I have used this process but was wondering about the longevity once set . What do others use ?
I use Cornice cement for the scenery. I once tried the adding of glue to the mix but found it really did not achieve any benefit. I colour the mix with brickies coloured mortar powders, which you can mix to make up various shades.
In the past I tried the plaster clothe & then netting over the styrene & found that it just added another layer of work to the process, although that is not saying it is something not to do. So in order to simplify the work I use Styro foam boxes & break/cut it in pieces to form the basic shape I am after, then cover with the cornice cement mixture working it to the shape I am after.
In the mix I put vinegar to help with delaying the setting of the mix, also disinfectant, & washing liquid. the Diso helps keep mould at bay, with the dishwashing liquid seems to keep the plaster in a dampish state for a couple of days, even though basically set. That provides time to scrape & cut the plaster for rock cuts & any other working.
By covering the foam with at least 12mm of the mix it helps not having cracks. Using this sort of mix, & application I find it sets quite hard, & the old layout prior to moving had some sections of the scenery moved here but I never used it & it survived that, & some was around 7 years old when we moved & it arrived in a trailer no worse for wear.
I also use the same mix to raise the levels on the layout by just pouring on the baseboard & no problems with cracking so far. In corners & layout edges such as low embankments, I use flat styro foam with the same mix over the top, cheap & I cut down the thickness of the mix on these locations, the foam under the mix provides the best method for me to plant trees into.
We live in an active soil area where there is a fair bit of movement created, that shows up more on the backboards but so far that movement has not affected any of the scenery, except some very narrow embankments which have been replaced.