# Building a fake rock background - The definative guide



## Jonny357 (Nov 8, 2008)

Im half way through building a fake rock back ground for my chinese water dragon and i though id right a step by step guide. alot of people post pics of the finished product but it can be difficult to work out how they did it! so here goes....

Materials you will need:

polystyrene / space foam
sharp stanley knife
Plaster-board saw
No More Nails (prefereably the tube and gun version)
brush
fine sandpaper (wet and dry paper works well)
tile grout
paint (emulsion or acrylic)
sealent (G4 pond sealent, epoxy resin, boat varnish)
strong paintbrush
A very understandng girlfriend

Step one

visualisation - the most important part of the process, make sure you have a clear idea of what you are setting out to achieve, draw a few pictures, designs etc

Step two

construction. i found space foam much much more suitable than polystyrene, its far denser and easier to care, and does not break up into small balls/chunks. you can get it from b&q for 20 quid for four times 4ft by 1.75ft sheets.

Using the plaster board saw cut out the desired shapes, it works a damned sight better that hacking away with a knife, and its flexible blade and knife handle mean it has it can easily cut corners, waves, notches as you saw. you will find this creates a very rough unsightly egde when cut. use the brush to remove excess foam. do not glue them together yet

then use the stanley knife to bevel and shape the areas along the cut to give it a more rock like shape. cut notches in the top of the background and continuing them downwards as cracks looks especially good. you will want to use a stanley with a long flexible blade. if you extend the blade to its fullest you will be able to use its flexiblity to cut concave shapes out of the flat board giving you greater texture and depth.

Once you are happy with your indiviual shapes and formations you will need to sand them down. while you may think that the lumpy rough areas left by the saw may provide good texture, they are not, as they are a bitch to grout over, and most rock formations have a natually smooth shape due to erosion by wind and water. use the sand paper to smooth these off, and over the flat surfaces to remove the texture of the poly or space board. make sure any platform/ledges you build are well supported as they will not support themselves and the lizard without any form of support structure

once smooth and sculpted its now time to glue them together. you realy cant skimp here, use no more nails, dont use own brand grab adhesive. i tried with b&q's own grab adhesive and it didnt prove to be anywhere near strong enough. dont skimp on the glue and make sure you seal around the edges with glue

Grouting

You will need to leave your construction to dry for around 24 hrs as the adhesive needs air to cure, and so if you grout over it straight away the glue will not dry. once the glue is dry its time to grout apply with a sturdy paintbrush. you can get 1kg boxes of grout powder for around £4. its best to use the powder rather than ready mix as that way you have a greater degree of control over the viscosity of your grout. your best bet is to use wall tile grout that is water proof and suitable for showers/swiming pools etc. however, if possible find one that does not contain fungicides as these can be harmful, however its next to impossible to find ones that dont. 

the first coat needs to be very runny in order to fill all the pours in the board. dont be tempted to use few thicker coats as this will leave you with a difficult texture. after this i would advise applying two thicker coats to fill and smooth over the background, giving it a more natural, organic look. also these provide most of the strenght. finally a last runny coat will help to fill in all the little gaps/holes created by the grout itself. when you apply this, take time to ensure its well work into the background with the brush and you will be rewarded with a nice smooth, well textured final result

make sure the each layer of grout has plenty of time to dry between each coat, as with the adhesive if you grout over a damp layer it will not dry, and will fall off and break appart fairly quckily.

Painting

which paint you use is entirely up to you. i used emusion as it is cheaper in large qaunties, however make sure you look on the back of the time and choose one that is low VOC (volatile organic compound) acrylic is also entirely acceptable. emulsion is good however it is not as waterproof as acrylic, i will explain sealing later.

the first stage is to paint a strong solid base coat. for rocks such as granite i would use black while for rocks such as sandstone a dark red would be perfect. 

next build up layers using a technique called drybrushing. dip your brush into the paint and then, using kitchen paper wipe the paint off, so you brush appears 'dry' this will leave a residue on the brush. next gently brush the brush over the background. you will find that this highlights the raised parts while leaves the darker shades in the recesses. make each sucessive coat lighter untill you achieve the shade you want. the first layer should be a fairly heavy drybrush which each coat after being progressively lighter.

a nice effect is to highlight with a light colour all the stark edges, along crack lines, ledges etc.

of course instead of painting you can use pva and sand, the red exoterra desert sand would make a sweet desert sandstone.

Sealing

this is a tricky issue. some people do not seal afterwards, if your lizard is from a desert environment and is exposed to low humidities it may not need to be sealed if painted thuroughly, in this case i suggest you use acrylic. however, tile grout contains some nasty things like chromium and lime, which can cause burns, so i would always suggest always sealing it. however asthetically it can be a bit displeasing, leaving the rock with a shiny 'wet' look. 

there are a few things you can use to seal. G4 pond sealent is cheap and effective (around £10-15 for 500ml said to cover 5m square) , although for high humidity will require 3 coats for full water resistance, however for desert conditions i think one coat will suffice. although it needs 2 weeks for a full cure before you use put it in the viv. 

Best bet is epoxy resin. however this is expensive, around £20-30 per kg it is completely water resistant and non toxic. even the fumes are said to be non toxic. however it is still best to aireate for a few days anyway. however epoxy CAN yellow under high UV. i am unsure if this would be an issue in a viv but its worth bearing in mind.

Finaly boat/yatch varnish is a good choice. its completely waterproof (obviously) and resist to high levels of UV. however this will need several weeks to aireate, so all the chemicals can be released before its put inside the viv.

i would not advise sealing with pva, though it may be fine for dry vivariums, for high humidty vivs and those areas in direct contact with water will cause the pva to cloud and go milky. while this does not compromise its strenght as a barrier it is unsighly. 

Instalation

just a quick note, use no more nails again to stick it to the back of the viv and then use aquarium sealant (about £20 quid a tube) to seal the edges, sides and bottom to the viv to stop water and those pesky crickets getting behind. 


Right im done now, i hope this helps all those who want to under take such a project, it is hard work and time consuming, but very rewarding. sorry i havent got any pics, i will post some up tomorow. i dont know if this is worth of it, but maybe a sticky?

cheers!!!


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## snowyj99 (Feb 28, 2008)

Very good guide but probably better under the habitat section":2thumb::lol2:


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## Jonny357 (Nov 8, 2008)

good point lol


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## jack14 (Oct 4, 2008)

thanks i am thinking of making 1 of these soon this will help alot this should be a sticky :notworthy:


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## makeitandskateit (Jun 15, 2008)

sticky, I'm so bored of all the "how do I.." posts


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## thescalesofbabylon (Mar 29, 2009)

wud ov taken me weeks write that lot :lol2: so take me hat off to ya there.

personally i would not wait 24hrs for ya grout dry... use a fan heater : victory: ya can do all coats in a morning or afternoon, far quicker. thats what tilers use to set it off in cold weather so do it !

and i would not use grout at 4 kwid, i used flour and water mixed wiv ya pva... same result at a fraction of the cost :whistling2: think i paid 9p for a big bag of flour... then ya crestie can sit on the plains(flour) setting :lol2:


sorry that 1 was tacky :blush:


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## snowyj99 (Feb 28, 2008)

thescalesofbabylon said:


> sorry that 1 was tacky :blush:



Shouldn't be tacky if you use a fan heater to dry it!:lol2:


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## Jonny357 (Nov 8, 2008)

yeah same mate, its so annoying everyone asks the same questions because theres no definative answers for everyone to refer to


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## lewi (Mar 15, 2009)

Nice one mate, 

You might want to add that instead of painting it you can give it a coat of PVA then cover in sand, then coat in PVA if worried about impaction to seal sand, what i did anyways, looks pritty cool.


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## Seems Unlikely (Feb 2, 2009)

Jonny357 said:


> Sealing
> 
> this is a tricky issue. some people do not seal afterwards, if your lizard is from a desert environment and is exposed to low humidities it may not need to be sealed if painted thuroughly, in this case i suggest you use acrylic. however, tile grout contains some nasty things like chromium and lime, which can cause burns, so i would always suggest always sealing it. however asthetically it can be a bit displeasing, leaving the rock with a shiny 'wet' look.
> 
> ...



I have built a rock face in one side of my current viv build but have come up against the problem of whether to seal? having read your bit on chromiium content and lime in the grout it probably is best i do. I have not painted as i have used a beige tile grout from screwfix, with a brown grout as an undercoat. This has given (in my opinion) a reasonably good looking finish. I want to get it finished soon as possible so have been looking at epoxy resin, as you say though this is expensive. I found the following article about epoxy vs polester resin,
Carbon Fiber 101!
which states that is is polyester resin rather than epoxy that yellows in UV. It does however warn that epoxy is toxic in liqud form so this will need to be taken into account. I will get some purchased and post how well it goes. 

Also looked at yacht varnish, this has a high VOC so may be rather toxic and smelly, also looked at eco-varnish but reading the small print it contains 30ish%less petrochemical content, replacing it with castor oil, not sure this amount is enough to merit choosing it? 

It's a bugger aint it, you want to do right on the job and end up talking yourself into a corner!!

Corin


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## paulab (Mar 26, 2009)

thescalesofbabylon said:


> wud ov taken me weeks write that lot :lol2: so take me hat off to ya there.
> 
> personally i would not wait 24hrs for ya grout dry... use a fan heater : victory: ya can do all coats in a morning or afternoon, far quicker. thats what tilers use to set it off in cold weather so do it !
> 
> ...


Well i need to go out for grout. So come on tell how much flour water and pva do we need to mix.


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## thescalesofbabylon (Mar 29, 2009)

paulab said:


> Well i need to go out for grout. So come on tell how much flour water and pva do we need to mix.


:lol2: sorry m8 been busy and forgot about this 1 :blush:

its just common sense really m8, i mixed enough to do 2 pieces which i had created as a sample for it. but bearing in mind i was using a fan heater also to help it along. 

note:: i already had one going in the loft so dont rush out to buy one lol :Na_Na_Na_Na:

the best advice i could give you is when mixed i found that a consistancy between yoghurt and double cream was sound (can see me starting a cookery course :blush: ) it didnt run all over the place and it didnt stodge to create a blobby mess and dried fairly quickly to recieve another coat.

as for the pva/water well its pva! dont matter how much water you add it will still go off. mix ya pva and water together first though then add to flour. rough guide would be lets say 5 parts water to 1 part pva.

you could be mixing a thimble full or a bath full so cant give the true recipe details, just remember the consistancy your after yoghurt/double cream :2thumb:

try it out on a spare piece like i did, ya cant go wrong, every time its coated its sealed

have not tried adding substrate to the mix, think that could get messy so once you have got what your after, just use pva/water to coat then bang ya sand or whatever on, i got carried away and was doing a collage with in night garden and telly tubbies pics :blush:

after that you need to bake it for about 25mins on gas mark5... and if you do this line you need a :bash: :lol2:


and to prove its not a joke :lol2: still a bit of tweaking but ill get there :2thumb:


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## paulab (Mar 26, 2009)

:lol2: Thankyou.


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## Jim2109 (Mar 30, 2009)

great call on the space foam!!

i had a similar thought to you in that polystyrene breaks up too easily, and i thought it would be hard to accurately shape. so i started out using Oasis foam, the green stuff that is used for flower arranging. its absorbent as well, so i was using polyester resin and fillite to harden and seal it.

but its so hard to work with because it crumbles away so easily, and i was pulling my hair out this morning. so i went to Wickes and bought a pack of Space Foam (same price as B&Q for the same size and quantity of sheets), started playing with it, and noticed that it was dense enough that i could probably sand it. but then i remembered some tools i have called "surform planes". they are basically sharp cheese graters lol, which are used for shaping wood. they work an absolute treat on space foam!!! so armed with a loose hacksaw blade, stanley knife, and my surform planes ive finally found a method that is working out without all the hassle. ive done the first layer of grout, so we will see how it turns out.

many thanks for this guide, i havent followed it religiously, but it gave me the ideas i needed to solve my problems


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## Jonny357 (Nov 8, 2008)

Jim2109 said:


> many thanks for this guide, i havent followed it religiously, but it gave me the ideas i needed to solve my problems



now surform planes, thats a brilliant idea, i love how things evolve on forums

your very welcome, in honesty id quite forgotten id written it lol

yeah im so glad i used space foam, bit more expensive, but it really pays dividends in the end

i cannot wait to see you WD build in all its finish glory, looks like its going to be pretty specially, especially the waterfall!

good luck!!!


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## Jonny357 (Nov 8, 2008)

Seems Unlikely said:


> I have built a rock face in one side of my current viv build but have come up against the problem of whether to seal? having read your bit on chromiium content and lime in the grout it probably is best i do. I have not painted as i have used a beige tile grout from screwfix, with a brown grout as an undercoat. This has given (in my opinion) a reasonably good looking finish. I want to get it finished soon as possible so have been looking at epoxy resin, as you say though this is expensive. I found the following article about epoxy vs polester resin,
> Carbon Fiber 101!
> which states that is is polyester resin rather than epoxy that yellows in UV. It does however warn that epoxy is toxic in liqud form so this will need to be taken into account. I will get some purchased and post how well it goes.
> 
> ...


yeah i completely agree, having said that, yatch varnish can yellow aswell (buuut if you imagine the amout of UV a yatch hull is exposed to both from sun and reflection off the sea im hardly suprised) to be honest i dont think the epoxy will yellow under vivarium conditions, if it did i think it would take a fairly long time period for it to do so.

sorry for the late reply, i forgot id writen this, hope everything well ok!


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## joffy (Feb 14, 2008)

Any links to what space foam is please? Looked on B&Q site and googled but just got info on the space shuttle!


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## Guest (Sep 1, 2009)

joffy said:


> Any links to what space foam is please? Looked on B&Q site and googled but just got info on the space shuttle!


It's called space board, you can only get it from a B&Q warehouse, £20 for a pack of 4, I am selling 2 sheets for £8 (taking it to doncaster) as they are pretty big and I am only using it for an exo terra 

linky: http://www.diy.com/diy/jsp/bq/nav.jsp?isSearch=true&fh_search=space+board&x=0&y=0


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## joffy (Feb 14, 2008)

Thanks very much.


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## thepidgon (Feb 15, 2009)

Sticky!!


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## Lizardman092 (Nov 16, 2009)

Is it possible to use any varnish to seal?
as long as it is given time to air?


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## coolturtles (Jan 18, 2008)

from what i can gather any varnish will work but you can get water based which is low oder


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## C.Bruno (Oct 8, 2008)

good thred!


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## Arrogant Dew (Jul 21, 2009)

Is the advice in this thread the same for completely submerged sections. e.g. pond areas and drinking bowls.


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## s3kcy (Dec 4, 2010)

great tutorial, just what i needed


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