Faux (fake) Rocks: Build Log with Pics.

mh32 · #1 (**permalink**) 10-11-2008, 02:25 PM

Well I've been working on this for a while now and decided it's time to post my progress. I attempted a fake rock process I saw on dendroboard. I think it has turned out ok so here it goes.

First off I decided I wanted to make this outside of the tank to save on clean up inside the tank during the cement process. I'm glad I did for ended up causing a few problems in the end but I still think it was worth it. So I made my false bottom out of egg crate and made it small enough that I could take it out fairly easily.

I started out with some chunks of foam I believe polyethylene foam (like the stuff those pool noodles are made of also same foam as some computer supplies are shipped in.) I cut them into smaller chunks and hot glued them into a rough shape resembling rocks.

I mixed up a very runny batch of thinset (the type of concrete used to level out cement floors before putting down tile) It was so runny I used a paint brush to just paint it on probably the consistency of cream. I used it so thin so I could get into all the small cracks. I used Ultraflex 2 brand found at Lowe's. You use this type because it has a polymer added to it to allow different layers to stick to each other.

After that layer had set up a little I put on another layer (this stuff dried pretty fast) This layer was a little thicker but still thin enough I could use a paint brush.
This is after it dried up a bit a lot lighter than I thought but it's fine.

After the first two layers the edges were still pretty square and not very rock like. I made the third layer pretty thick more like peanut butter and just slopped it on with my hand (use gloves with this stuff it will dry your hands out fast.) I let this layer set up for a bit and then started to smooth out the shape with my hand (if it sticks to your hand let it set up a bit longer or just get your hand a little bit wet.)
You can see on the top left where I started to smooth it out a bit.

I wasn't 100% pleased with this layer so I did one more. Really thick this time. I could almost make a ball out of it. This layer was fairly easy to shape and finally got the look I wanted. The good thing about this method is if you don't like the look add more cement and do it again. After the last layer set up a bit longer I carved out some of the cracks just to give each rock a little better definition.

Next came the easy part. Soaking. I put whole thing in the tank where it will go, weighted it down (even with all that concrete it still took 35 pounds to hold it under water) and filled it with water and vinegar. I'm told the water and vinegar help the cement to cure and neutralize the pH. I soaked it for about two weeks changing out the water every few days.

Next came the painting I used a non toxic acrylic paint. For the first layer I thinned the paint out quite a bit using water. It was basically black water. I covered the whole think in this black paint/water and let it dry for a minute then I took a damp cloth and wiped off as much as I could. It still looked a little dark to me so I sprayed the whole thing down with the hose. Leaving the black paint in all the cracks and crevices.
This is after the first black coat and spray down.

After that I began to add some more color. I used browns and orange and green. All watered down. I made the mistake of just painting the concrete when I tried a small scale version and it looked like painted concrete. So I watered it down and just dabbed it on with a sponge and then would lightly wipe it off until I had a fairly natural look.

I did several layers until I was pleased.

After I was pleased with my color I let it dry a for a while and then did one more layer of the black paint/water mixture. Just to get the black in all the cracks again and create more depth and shadows. I sprayed it off again with the hose and here is the final product.

Now to the problems I was talking about. I've had this problem in other vivs as well. You fit everything perfectly take it out do everything you planned and when you put it back in it doesn't fit quite right. Well it happened to me. With all the concrete on the foam and shaping it didn't fit in the corner like I wanted it to. It was flush in some places like I wanted but other places there were up to one inch gaps. These gaps needed to be filled so a curious critter doesn't climb back behind and get lost or stuck. I assumed this was going to be the case so I had some great stuff standing by (amazing, I'm actually going to use great stuff in the way it was intended to be used). I wanted to keep this tank not totally permanent just in case so I lined the tank with wax paper then filled the gaps with great stuff. When it had cured I peeled the wax paper off and put a small bead of silicone around the edge and VOILÀ!

All I have left now is to put in some gravel on the bottom and a little substrate and a few plants. I might try to cover up the great stuff on the side and top but it is not very visible I'm not to worried about it. There won't be much land area mostly water. I will fill the tank up about half way so it will be about 12 gallons of water. And will put some fish and probably some fire belly toads.

sinflspeed · #2 (**permalink**) 10-11-2008, 03:13 PM

Nice job. Looks great! Can't wait to see it planted.

froggsong · #3 (**permalink**) 10-11-2008, 09:49 PM

Simply amazing! Want a sticky????? Too late! Great job.

tat2stu · #4 (**permalink**) 10-12-2008, 08:41 AM

great piece of construction
love to see it fully functional
great 3rd pic looks like loads of chocolate

Pavel · #5 (**permalink**) 10-12-2008, 09:57 AM

Well done!

I'm really surprised how much the thinset lightened up -- from brown to gray -- wouldn't have expected that.

So now a few Qs
1) What's the bule material on the bottom of the tank?

2) How light wieght is you finished rock?

3) Do you have a pump in there? & if so how easy is the access?

4) Is there going to be waterfall action going on? (& again, if so take a pic of the access and openings for us nosy folks!)

Again, very nice job!

mh32 · #6 (**permalink**) 10-12-2008, 09:51 PM

Thanks for the comments. Yeah you wouldn't want to eat this chocolate.

To answer your questions:

1: The blue on the bottom is an under gravel filter I was thinking about using. I changed my mind though.

2: The whole think weighs maybe 5 pounds

3: I do have a small pump underneath to power a small waterfall access is fairly simple I'll post some pics.

4: Yeah I'm hoping to have two waterfalls one just for fun and the other will be from the filter.

I'll try to get some pics up tonight.

mh32 · #7 (**permalink**) 10-12-2008, 10:22 PM

Well I was able to get these sooner than I thought. To access the small waterfall pump I just have to move this sphagnum moss.

Remove the screen and eggcrate.

And I can reach it fairly easily.

The only problem will be if the pump dies. I'll have to cut the cord to get it out (it's siliconed in the back) But that's not a huge deal any way.

P.S. are these photos too big?

MBS · #8 (**permalink**) 10-13-2008, 10:58 AM

Very nice! I always wondered about using paint in aquariums though... Will it not come off on the half that's submerged?

mh32 · #9 (**permalink**) 10-13-2008, 12:05 PM

Quote:

Very nice! I always wondered about using paint in aquariums though... Will it not come off on the half that's submerged?

From what I've read it eventually will but hopefully by that time there has been some algae or moss growth to make it look even more natural.

froggsong · #10 (**permalink**) 10-14-2008, 01:03 PM

Isn't there a clear sealant that is aquarium safe that you can use? It seems like one of the guides on building faux rocks that I have read said something about using a sealant... I'll have to try to go over the links I have and see if I can find the one I am talking about.