Building False Rocks for your Enclosure

Written by Stuart McDougall on December 10, 2006
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PART 1 (...Continued) - Getting funky with the poly!

Now use the craft knife open the knife to 1" of blade showing. I made several cuts into the 2" foam up to 1" deep and ½ inch to 2" wide into the foam then literally pulled it out with my fingers giving a rough undulating effect before covering it with grout. This will give you a great uneven surface and a better look for the finished project.


Now cut the first shelf and fit like before by cutting a snug groove into the poly then add a second shorter shelf above the first using the same process. Then make a central support column where the ramp joins the shelf. I made mine from larger to smaller as I went up.

In retrospect I think I would of preferred an hourglass shape. Those I have seen since in this shape tend to look more realistic.

Once all the shapes are cut, it's time to get funky with glue and poly expandable foam. I also added some bits to the shelves just by ripping apart off-cuts of poly.

This was then left for 12 hours to dry

At this point, I carved in some detail to the central column using a craft knife, to make it stepped. I also removed any extra expandable foam and did more detailing in to it. Lastly, I removed the square edges and arched the bottom edges of the horizontal shelving and the ramp. After which, a I gave it a quick rub with a good medium grade sand paper. This finished off rounding the edges of the shapes.

PART 2 - Layering The Grout

Day 1

The 1st layer was brushed on using a thin paste grout making sure I covered the whole thing.

The 2nd layer was done once the first had partly dried. I repeated the steps of the first layer but slightly thicker and some places were stippled (mostly the vertical ones). Then I left it overnight to dry.

Remember to cover all of the structure including the inside of the hide.


Day 2

For the 3rd layer, I used the larger flat artists pallet knife. I used this knife for all the flats so as to apply a good thick coat to walking areas. I also carved some basic features into the grout.

For the 4th layer, stippled the vertical areas with a thick paste grout. About 2 hours later, I went over any thin looking areas. Then I again left it overnight to dry.


Day 3

The 5th layer was the most important for me, as this is the main detail layer where I applied grout to all the bulges and flats.



Image Apply a thick coat of grout to an area to be detailed. Allow the grout to set for a while without letting it go to hard. 20 minutes or so should do it. It will look a little lighter in colour with a sandy sort of texture. At this point I started to carve details. I used the side and the rounded points of the smaller artists tools, dragging, cutting or pressing the desired strata shapes into the grout.

Once you have it looking the way you want, leave it again for a few minutes. Then brush very lightly over the top with a soft 1" paint brush. This will remove harsh edges giving it a more sandstone look of being worn and weathered.

If timed correctly, you can apply the thick coat of grout to an area, and as this is setting, you can be detailing somewhere else.