I haven't bothered doing a workbench thread before as I intended putting most of this sort of thing in my blog. I'm not sure the blogs are that widely known about and some of the stuff I've been working on may be of interest to a wider audience so I thought I would also do a workbench thread.
One thing I have been doing quite a lot of is using plasterboard as a medium for cliffs, walls etc. It has the benefit of giving a more authetic appearance than paper or plastic and in my case, being free; sort of.
While renovating my garage I used a substantial amount of plasterboard and was left with a fair bit as I had over ordered which I had initially intended to chuck, but was advised strongly against doing at the time by my father in law who cited various DIY projects where it could be used. I had been doing a fair amount scenery building with plaster and it dawned on me that the same brick/rock effect would obviously be available from plaster on plaster board as it would on plaster. I had a fair amount of rock cuttings to do and thought that as many of them would be cuttings as opposed to cliffs that I could use the plasterboard to make these.
The plasterboard modelling process is pretty straightforward. I would recommend doing this outside and over a bin if you can. You may wish to use a mask and goggles as this is very messy.
The section of plasterboard cut to size.
Insert stanley knife or screwdriver between the card covers into the plasterboard.
Prise away the plaster on one side.
Continue to remove all of the paper from one side of the plasterboard leaving the other to maintain structural integrity. I initially used a screwdriver but this is incredibly slow and found a Stanley knife far quicker. By wedging the knife in the side and twisting a shattered rock effect can be gained while removing the paper. Once all the paper is removed from one side you can use a screwdriver to add more effects to make it look more like shattered rock.
Once the paper is removed, a series of coloured washes can then be applied to resemble the rock of your choice. For the first coat I used a matt enamel type paint diluted with turps to seal the plaster. The colour to choose depends on what type of rock you are after, white for chalk, grey for Oolitic Limestone, beige for Portland Limestone, red for Central Scottish sandstone. You really don't want any dust getting onto the tracks or into the inner workings of your locos. For subsequent coats you can weather the rock face or add other colouring to resemble the type of rock you are trying to represent, e.g. spots of pinks or whites for granites.
This is the sheet when placed in position on a slope. If you are using water based stains for the secondary coats it is best to do this on a warm day or in a heated room as you want the plaster to dry quickly and not absorb the water. I tend to use several layers of washes to build up the weathered look. I have a large container of stain wash which I apply every time I am out there to build up the layers.
And with a bit of scenicing.
Plasterboard would also be ideal for making brick walls too however once you have removed the surface paper lining you will have to level the surface again by sanding it flat. It may be easier to apply plaster to the surface you intend to look like wall than to do this however it does offer one major advantage; it is difficult to line and etch the plastered surface while it is attached to a structure on your layout. It is comparatively easy to work with a sheet of a foot or so of plasterboard and to etch lines into it with a modelling knife and steel rule. There is also the ability to "point" the brickwork which is best done on a flat surface.
As before the first step is to strip the paper from one side leaving the paper intact on the other to preserve structural integrity.
Having done a fair bit of this over the last month I have found that you now want to file the stripped surface flat if you want an even new build sort of finish. If you do not then leave it uneven and it will represent older crumbling brickwork. The next stage is to use a steel rule to etch the brick work effect into the plasterboard.
The vertical lines have to be done by hand and yes, this is very time consuming.
Next step is to give it a colour wash with your choice of brick colour thinned with turps. I then add subsequent layes of water based washes to weather.
These are added in the form of tiles one by one to make up the area required. Joins can be disguised, if not tight fitting, by buttresses or weeds.
These are all attached with PVA glue. The ends and buttresses can be easily made up from small offcuts.
Here are some pictures after scenicing has been applied to the brickwork.
In conclusion it is a lot of work but is worth it for the authentic effect. It's probably better for stone than brick as bricks are pretty small in HO/OO scales. Here are some more pictures of structures I have made using this technique.