How to make rock faces

Creating realistic cliffs and rock formations in miniature is surprisingly difficult but with these techniques, some practice and a bit of time anyone can do it.

I can’t believe it.

I’m just starting to think about creating the rock faces and quarry for my Cornish themed layout and went to refresh my memory on the technique by looking up making rock faces amongst the hundreds of tips here on ModelRailwayEngineer.

To my surprise, I discovered only one tip on my making them and that was using bark to make for small rock outcrops! In the five years writing about my experiences and model making on this blog I’ve completely overlooked making model rocks!

Tut-Tut!

Model making ladies and gents, let me correct this omission now with these, my two best techniques.

For Small Areas and Gauges

First up is the Aluminium foil method.

This is easily my most preferred choice for rock faces covering smaller areas, diorama’s and railways in the smaller scales, N or Z gauge in particular.

It’s explained below by TheTerrainTutor.

Essentially, it’s is a 5 step approach:

1. Crinkle up aluminum foil,
2. Form it into a square with upturned sides, creating a box into which you can pour fluid without it spilling,
3. Mix up a very fine Plaster of Paris like substance,
4. Pour this over the mold and leave to set,
5. Peel off the foil and then paint (covered below).

In the past, I’ve used normal plaster but more recently, and as per the video, I’ve switched to using Ultracal 30 Gypsum Cement. The benefit being it hardly expands when setting – so you know the size of the area you spread it on will be the size of the finished rock face. I’ve found some other materials can expand by considerable amounts and spread well beyond the space I had in mind. This is particularly annoying when you’re making cliff faces that run close to track!

It’s also very fine and gives a smooth finish.

Rock faces covering large areas

For larger areas and larger scales, perhaps mountains and OO/HO gauges and above, a different technique is used:

I apply this over a basic shape formed from polystyrene (as found in sheet and packaging material).

As you can see this creates very credible larger rocks faces that can cover big areas although it is time-consuming.

The above technique works well for nearly all types of rock. The only difference will be when modelling slate or granite, as I’m doing on my railway.

For these, apply the plaster as in the second video and then use the technique described by Tony Hill in Creating Realistic Landscapes for Model Railways: drag a ruler or flat surface against the wet surface and drag it across creating a flat finish. Then use the edge or tip of the tool and draw vertical or slightly angled cracks so creating slags of slate and granite.

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Extra: Don’t forget to cover your track with masking tape before working with the plaster etc. Cleaning this off your rails isn’t a fun job!

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To this technique, I’d add perhaps the best piece of advice and something I learned when doing some wall plastering.

I couldn’t get the smooth surface I wanted until a colleague recommended I grab some of the plaster mix and experiment with it away from the actual area to learn how it drags with different tools and stages of it’s drying time and then how paints behave when applied.

This was invaluable at the time and has proven even more so when making model rock formations. Understanding how the Ultracal or plaster mix behaves makes a massive difference.

What colours to use for rocks

With the surface shape made, it’s then a question of painting them.

I find it really useful to have a photo or two of landscapes and scenery to refer to when doing modelling. This helps me get the right colouring and and this is even more so when colouring and painting the rocks, which is covered below.

For colouring, there’s a helpful breakdown of what rocks (and their colours) are found around Great Britain in Creating The Rural Scene by David Wright:

• Limestone: Found from Dorset to Yorkshire, ranging in colour from grey to mellow golden to reddish.
• Sandstone: All over, with shades of grey to pink, purple and greens.
• Slate: Common in North Wales, Scotland, Cornwall and Cumbria, colouring includes greys and purples but also green and brown.
• Flint: Typically, in the South and South East of Great Britain and East Anglia.
• Granite: Scotland and in the far West (Cornwall). Usually, dark grey.

So that’s it, my two favourite techniques covered and a huge omission corrected.

These techniques have produced some of the best rock faces I’ve seen.

You may need a few ‘practice runs’ (or more than a few in my case!) but a good rock and cliff face will transform yours and my layouts and the satisfaction gained by developing new skills and improving your layout will more than make up for the time.

Good luck, and as always I’d love to see any photos of your completed rocks faces. If you’re not already a member join the websites companion group and community on Facebook and share your photos.

> A final, personal, note: I spend a huge amount of time testing, photographing, writing and researching techniques for these articles and pay for all the running costs of MRE out of my own pocket. If you found this article useful you can support me by making a donation on my fund-raising page. Thanks and happy modelling, Andy.

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