One way to make a Fake Rock

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Caveman

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G'day everyone, just thought I'd share an easy way to make realistic fake rock. This technique is just a modification of techniques used to make concrete rocks for landscape gardening. All I've done is take the final finish and apply it to a lightweight polystyrene base. The result is a tuff and very realistic lightweight rock that will easily handle dragons and small monitors. With a few more coats it would probably handle larger monitors too. The downside (like most realistic fake rock) is that it is not a sanitary surface. Like a real rock it is rough, slightly porous and hard to spot clean. I would try to make it so you can remove it occasionally and hose it down. Anyway this is what you need.

Polystyrene
Scavenge around to find polystyrene. Try tips and junk yards, I got more than I'll ever need from a junk pile at a milk factory. It was an old freezer lining but once I removed the tin, stripped the glue and soaked it in bleach overnight it came up as good as new.

Color Hardeners
Color hardeners are a mixture of off-white portland cement, mineral oxide pigments and fine sand (1:1:1). They are used to add color to various cement based products and dry almost as hard as concrete. They are sold in powder form and you can buy the oxide powders separately and make your own by mixing the above ratios. Art and hobby stores sell small amounts of mineral oxide powder and common colors can be found at most hardware stores. A 1kg tub of black, brown or red pigment costs less than $10 and a small bag of portland cement around $5.

Concrete Bonding/Sealing Agent
You need a concrete bonding/sealing agent (acrylic polymer) to bond the color hardeners to the polystyrene as well as each layer of hardeners to the next. This forms a plastic like bond giving flexibility that strengthens and holds everything together. There are many different brands available so look for a cement additive/surface bonder/sealer that dries clear and non-glossy. A similar product that you can readily find is Bondcrete and a 500ml bottle costs less than $10.

Note: This is essentially a concrete rock and these products will not harm your animals but if you want to use your rock as a water feature I would use a product like Pondtite between the base coats and final color.

The polystyrene before I ceaned it up and color hardeners. The dark black powder is straight mineral oxide pigment and the lighter black above has been mixed with sand and cement.
Foam_Colors.jpg


OK, lets start by making a rock formation. In theory you could use any material that's rigid enough to hold it's basic form but polystyrene is easy to shape. Just start breaking the polystyrene away at the edges and shaping it. I use a paint scrapper and a couple of screwdrivers. Don't get too fussy it will break away and look natural on it's own just use your thumbs to round off sharp edges and make the shapes you want. Use the KISS principal because you don't want areas that your animals or insects can get to but you can't. Also watch out for crevices you can't get to with a paintbrush (if you have to get complicated coat hard to reach areas before gluing your layers together). Making a built in wall is pretty easy, just start at the bottom and go for it. Making a 'free standing' rock is a little harder and it's easier to start at the top and work your way down.

The basic polystyrene structure. I use a latex based glue to hold everything together. It dries fast and seems to hold better than fast drying hard glues.
Foam_2.jpg


Now just coat a section of your formation in Bondall and Sprinkle color hardener over it (just use a common color for the base coats, I use grey). Now grab a paintbrush and tamp it down so the powder becomes damp and pasty. Continue sprinkling powder and Bondall as needed until you have an even first coat over your entire formation (you don't want to make it too thick, just cover the polystyrene). Leave it overnight to dry and repeat this step (use Bondall and let it dry between layers) until you have the thickness you need.

Here is my rock after two base coats of color hardener. It's now a hard solid structure that would break your knuckles if you punched it.
Rockwork_1.jpg


Now all you need to do is color, texture, highlight and age your rock. The colors you use are totally up to you this is just an example of how to go about coloring your rock. Sprinkle a few colors over your rock so you get good variation and tamp it down with a paintbrush dipped in Bondall so that the rock is mostly one color with some areas darker and some lighter (use a dryer brush to get less mixing of color). Now mix a little dry sand with black, red, brown or whatever colors your using and sprinkle it over the surface while it's still wet, this will bring out the texture. Now leave it to dry overnight then wash off the excess and loose sand. What you are left with is the overall color of your rock and it's almost finished.

Rockwork_2.jpg


To add highlights to your rock mix the color hardeners with water to a thick pastey consistency and with your hands just add highlights of color here and there. Now all we have to do is tone the color down and age the rock. Mix black oxide powder, with water until you have an almost transparent mix (this is known as a tint or dye). Now just flick the transparent mix over the rock work. The idea is to tone the color down and make it look natural.

Adding color highlights. You can't really see it in the pictures but highlights add that extra touch of realness.
Rockwork_3.jpg


The almost finished rock after being tinted with black oxide pigment.
Rockwork_4.jpg


Once the tint has completely dried give it a final coat with bondall to seal in the color and your rock is finished. If you made your tint to dark wash some of it out and let it dry before sealing it.
Rockwork_5.jpg


And thats all there is to it! You now have a very realistic hard wearing rock, that is much lighter than a polyurethane rock of the same size.
 
RE: Fake Rock

thay look great caveman wish i had the time to make some... welldone
 
RE: Fake Rock

caveman they look great just wondering were you live and would you be interested in making them and selling, if the price is good i may be interested...if you live in sydney
 
RE: Fake Rock

That is awesome!

I've always wanted to have a go, but not known how to go about it. This topic should go under feature articles, or be made sticky. In any case i'm going to copy it to a word doc. So i can print it off.

Just out of curiosity, how much did it cost to make the rock, start to finish, in your guide?
 
Re: RE: Fake Rock

Pyror said:
This topic should go under feature articles, or be made sticky.

Your wish is my command! Well, sometimes....! ;-)
 
RE: Re: RE: Fake Rock

Great stuff. Based on the price of fake rocks these days, it really is a great way of doing things. I used to know a website that also gave step by step instructions on how to make them. If I can find it, I will post the link. :)
 
RE: Re: RE: Fake Rock

thanks for sharing your idea, ive seen other ideas using polystyrene and makeing fake rocks, but they usually end up looking abit tacky and not very hard. this one looks very good, ill definatley be trying this

can a rock pool be made for these, or would teh chemicals in it be released into the water?
 
RE: Re: RE: Fake Rock

That's phenomonal, I can't believe how strong your daughter is :) . You've done a brilliant job with the fake rocks - I don't have an artisitic bone in my body though so it wouldn't matter how good the instruction are, mine would still look crap.
 
RE: Re: RE: Fake Rock

Awesome Thanks mate, have saved it, will give it a bash. Looks great! :D
 
RE: Re: RE: Fake Rock

Thanks Caveman for taking the effort to share this with us.

Jason said:
just wondering were you live and would you be interested in making them and selling, if the price is good i may be interested...if you live in sydney

Me too and I said it first...:wink:
 
RE: Re: RE: Fake Rock

Nice work Caveman :) Have you had a go at making fake rock hides in a siimilar way?
 
RE: Re: RE: Fake Rock

You're a champion Caveman. That finished product looks excellent. I am going to give it a go as a lining for the back wall of my aviary using polystyrene sheets i had for fish tank bases
 
RE: Re: RE: Fake Rock

That looks brilliant Caveman!

In paragraph 3, titled "Concrete bonding/sealing agent" you don't actually name the agent you use, but later you start talking about Bondall, so I'm guessing thats your preference.

I recently read another article on making fake rocks that had an interesting technique - to give the polystyrene a natural 'rock' look (pitted surface), they suggested you use a brush to paint on Turps or paint thinner. This dissolves the foam, and by concentrating on one area you can create some really natural looking surfaces.

Haven't had an opportunity to try it just yet.

:p

Hix
 
Thanks guys, it's good to hear they look alright, usually I get the "why would you want to make a rock" response.

Hey Jason and Alexr, i'm down in Vic sorry guys but i'm confident you'll be able to do it.

Pryor, this rock would have cost around $15. You can expect to pay between $8 - $16 for each 1kg container of pigments and $10 for a pre-mixed bag of sand and cement but this makes a few rocks. You could even just use black and acheieve your color variations using sand.

Tommo, I don't think the thin layer of concrete would hold much water but you can definitly make waterfalls from it.

Browns, I haven't made any hides but I've been thinking about it. Polysyrene has unreal insulating properties.

Hix, Bondcrete is made by Bondall. I use another product but listed this because everyone would be able to find it. It's all much the same.

Cheers everyone.
 
G'Day caveman SPECTACULAR LOOKING ROCKS pat yourself on the back......... She who must be obeyed is copying your design but is getting a little disgruntled and not game to use the bondall as a final sealer. As she is doing a waterfall it needs to be very waterproof and the worry is that by sealing it this way will lose the "rock look". Does this stuff dry clear and will it be good enough for water on it all the time?
 
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