Making A Cement Decoration

[Katty]

I just rescaped my tank, and had the idea that a certain object would look good in a particular place in there. I wanted a sort of horizontal stone pillar with an aztec motif on it (Maybe it's cheesy, I don't care!), but they don't really sell what I'm particularly looking for. I've seen people make 3d styrofoam backgrounds covered in cement before, and was thinking I could do the styrofoam/cement method to make this little decoration.

Is there any specific styrofoam or cement I should use? Will I have to coat the object in anything or soak it before putting it in the tank? Is this even a plausible idea? I've never worked with cement before.


To give you an idea of what I'm going for, I'm trying to make something that looks similar to this or this in style/detail, but about maybe 4x2x2 inches in size.

 

[AstonN24vantage]

ive heard that cement can poison a tank?

not sure but if someone could confirm it...

 

[dayzofspeed]

i've seen journals on here dealing with this topic and they were using polysyrene and covering it with cement but i would double check if i were you.... i think i saw quick dry cement mentioned

 

[Katty]

I'll have to dig around on the forum then for some journals dealing with the backgrounds. I did see one that mentioned the polystyrene was better than the normal Styrofoam. I was also thinking maybe florist foam could work because it is so soft, I could get more detail onto it. But it might just dissolve and smoosh when I try to cement it...

 

[dayzofspeed]

that stuff is called oasis and i'm not sure how useful it would be because it tends to break up very easily and you could get polystyrene free from lots of places as it tends to be just thrown away. btw i think the design is kinda cool especially if you are going for an amazonian tank, it fits rather well imo

 

[Katty]

Thanks.

I think we might have bits of polystrene packaging in the basement. I could even experiment between the polystrene and the floral foam, if only I could determine what type of cement is safe to use, if any.

I have read that portland cement is the type to use? Also my tank's pH is about 7.2-.4, so I want to prevent the decoration from turning the tank into a lake Malawi paradise with the concrete.

 

[dayzofspeed]

its your choice obviously but i wouldnt use the oasis as its a bit of an unknown quantity and could easily deteriorate, and in my opinion i would seriously look into using a resin finish as its quite an intricate design you are going for and although i think cement would be fine for a rough finish like artificial rocks or something, I have used cement to make artificial stone in my garden but it isnt that good for intricate work. one thing i do know is that cement would definatly need sealing before going into the tank to stop it leeching. another idea that has sprung to mind is why not try to use the faces mouth as a way of circulating the water (sort of like a church gargoyle) or for aeration if you use an airpump. whichever route you go down i would love to see pics of the finished article.

 

[raptorrex]

I just rescaped my tank, and had the idea that a certain object would look good in a particular place in there. I wanted a sort of horizontal stone pillar with an aztec motif on it (Maybe it's cheesy, I don't care!), but they don't really sell what I'm particularly looking for. I've seen people make 3d styrofoam backgrounds covered in cement before, and was thinking I could do the styrofoam/cement method to make this little decoration.

Is there any specific styrofoam or cement I should use? Will I have to coat the object in anything or soak it before putting it in the tank? Is this even a plausible idea? I've never worked with cement before.


To give you an idea of what I'm going for, I'm trying to make something that looks similar to this or this in style/detail, but about maybe 4x2x2 inches in size.

when thy talk of cement, they are talking of SILICONE sealant,(used to "cement" parts together) well usually. even when using a concrete sealant. most sources suggest BIG PH problems with concrete.

just look at the ingredients in a bag of concrete. honestly, would you really use it, in a aquatic environment?

 

[dayzofspeed]

cement/concrete can be used in an aquatic environment providing it is properly sealed to prevent leeching, garden ponds are a prime example, there are also journals to be found on this site and others showing the use of cement (as in building cement not adhesives) as a surface for giving a rock like finish but it must be sealed, but as i said in my previous post i personally would use resin in this situation. I do understand where you are coming from tho as i remember as a kid building airfix models with polystyrene "cement" (glue)

http/www.fishforums.net/index.php?/topic/339846-my-diy-3d-background/ not sure if the link works but this is a 3d background using polystyrene and coated with cement

 

[Katty]

Did some more google searching and came up with some links (I'm kinda putting them here more for my reference so I can find them later):

http/www.plantedtank.net/forums/diy/42402-cement-concrete.html -suggests curing and/or sika top seal to deal with pH
http/ice1forum.suddenlaunch3.com/index.cgi?board=DIY&num=1115002332&action=display&start=0 -someone using sika topseal
http/www.aquaticcommunity.com/cichlid/homemaderocks.php -suggests curing for three weeks, perhaps adding acidity to the water

The sika looks promising but I don't know if I can find it in my area and not for a ridiculous amount of money :\

If anyone knows any good sealants/resins/coatings, I'd love to hear them. I'm not sure if I entirely trust waiting for the cement to cure to keep it from leaching stuff, and I'm not going to wait years for it to cure just so I can put it in my tank.

 

[dayzofspeed]

i think even when cured it should still be sealed but you can do this by painting the surface with the resin

 

[Katty]

i think even when cured it should still be sealed but you can do this by painting the surface with the resin

I agree, but do you have a recommendation for any brand/type of resin?
Would this kind of product be something I should use or am I looking for the wrong thing...?

Edit: also found this stuff?

 

[dayzofspeed]

what you need is an epoxy casting resin and i'm not sure of those loctite ones, are you sure they're not a glue. i've just checked online and read that you should be able to get an epoxy casting resin from a good crafts store. you need to make sure you mix the ingredients carefully so that the resin sets correctly and hardens properly because until it sets resin is actually toxic, but once its "cured" it becomes inert, it basically turns into something similar to plastic. I have been thinking more about your project and think that due to the small size you might be better making a mould rather than trying to sculpt a piece of polystyrene, it seems quite straight forward from what i've seen online just make a model out of modelling clay or plasticene then make a latex mould, it should allow you to get good sharp details too. you could try doing a search online for diy statues or something, there are loads of people out there doing this kind of thing so you should be able to get some really good tips, you would also need something to colour your resin with from what i've read it can be done by mixing an oxide into it,seems like a lot to take in right now huh? bet you wish you hadn't bothered lol, but who knows if you make a good one you could start selling them once you have your mould. just remember to check that all the ingredients you use are aquarium safe and you'll be fine

 

[Katty]

Haha no I actually appreciate the ideas. I'm a really crafty person so making a mould and stuff actually sounds fun. I'm going to do some searching around for resin casting tutorials and stuff. Thanks for the idea, I really like it.

 

[Katty]

I found out we have a few really good plastics stores in the area (Tap Plastics), which also has some good video tutorials on youtube. So I think the casting resin idea is pretty plausible at the moment. It's a bit more expensive than concrete and styrofoam but it sounds safer and I can use the materials to make other things as well.