# Is grout etc a must-have or can i use paint only?



## sparrow (Nov 14, 2015)

So I'm considering doing a background in either styrofoam (blue, hard kind) or a mix of that and some foam. (We haven't got the Great Stuff here. I could order a pond-safe one but I will not have any animals in this setup so I'm wondering if I can use whichever foam I get hold of or if plants will suffer? Or ...well, me?)

I've painted a styrofoam background for a tiny aquarium before. I used only acrylic paint on it and sealed with a transparent fish safe silicone. Didn't look great with the seal, tbh. I think I would have been better off just using the paint.

I see a lot of you use grout and epoxy when making styrofoam backgrounds, and I want to ask if there is a specific reason? Could I just not paint with acrylic paint right on the styrofoam/foam and leave it at that? (I want to make a rock colour)

Another question I have is, I saw some use a sort of silicone spray. Is this an aquarium-safe silicone spray? If not, is it not harmful? Or are sprays different from normal silicone? We have some types here but none say anything about being safe/vinegar based, so I'm a bit wary to use them. But is it a sort of "free for all" since I am not introducing animals, or should I still try to keep it as animal safe as possible? (due to the plants.)


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## chin_monster (Mar 12, 2006)

There are a few issues to deal with about grout -some of them are incidental, some a bit more serious.

-Grouts gets heavy very quickly. 

-Gout leaches quite nasty alkali chemicals while it cures (for weeks) which must be dealt with

-Grout obscures details created in the foam substrate, which may or may not matter depending on what kind of "rocks" you're intending to make.

-Grout is gapping filling, which means that the under structure needn't be perfect -sometimes this is a good thing

-Grout has a natural self imposed "melted" texture that either works for you or against depending on the type of "rocks" you're making



I build styro rocks with foam, toothpicks, gorilla glue and acrylic paint tinted Drylok masonry paint -and sometimes titebond 3 glue.

I'll carve, glue (GG or TB3) and secure (toothpick) a "rock" together and then coat it with a few layers of tinted Drylok to seal it and the paint it rock like.

Drylok isn't gapping filling so the details of the foam telegraph through which means the seams between layers of foam must be invisible before there are painted over -less you end up with weird straight lines in your "rocks".

Gorilla Glue expands and can be used as a gap filler, also to glue irregular chunks of foam together. Titebond 3 works better to make big solid pieces out of layers of foams.



I wouldn't be too concerned about using other brands of expanding construction insulation foam -it all seams to the same expanding polyurethane stuff. 

The only silicone sprays that I am aware of are lubricants not sealants / adhesive


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## sparrow (Nov 14, 2015)

I think you're right about the silicone spray, I only saw we're selling it here and thought it was silicone as in glue-like, but now that I look into it, they're all for lubrication, haha. 

(By grout I meant all sort of cement/sandy stuff just to be clear)

Thanks for the very good explanation, it means a lot. 

I've checked before, but cannot find Drylok anywhere in Norway. What is it exactly, and is Drylok special in it's type or would any brand similar be ok?

Would I need it to mixed with paint/over paint or would acrylics work alone? I mean, i know acrylics dont fade with water an humidity, but it seems everyone wants to cover the paint with something.


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## Seth W (Dec 19, 2015)

I'm sure you've checked their site DRYLOK Masonry Waterproofer but maybe a good hardware store has something like this?

Another option is to use self leveling (underlayment) concrete on open cell foam. I did this for my first tank and it worked pretty well, you still run into the issue of needing to neutralize it with viniger and baking soda. Sharp edges need some extra attention when building up a 2nd a 3rd layer but this is another option. This guy has a awesome thread about it http://www.dendroboard.com/forum/members-frogs-vivariums/22002-60-gallon-construction.html I've been told but havent tried it but the concrete used on making pools is like this but doesnt have the alkaline leach that normal concrete produces after it cures that could be another option. 

If you go this route use silicon cauking to glue the foam to each other and the background vs hot glue. I've only built 2 tanks so far so I'm no expert on this stuff. Given the choice I think the drylok and pink hard foam is a better option but sometimes you got to use whats available.


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## chin_monster (Mar 12, 2006)

Drylok is a masonry waterproofing paint that is approved for potable water storage. It's quite a bit thicker than "normal" paint with a lot fine mineral / sand content that makes it durable.

I'm sure there's other brands of similar paint. I'd look for paints that were designed to prevent water seepage in basements or building foundations if I were to be looking something like it in another country

I wouldn't have a problem using waterproof acrylic paints by themselves if I didn't have Drylok but I do like it's thickness, strength and substance compared to layers of normal paint.

If I were wanting to make eroded, round-ish "rocks" I'd be much more open to using cement / grout coated foam but I'm more into jagged sharply fractured looking "rocks" and the thick oozing nature of concrete obliterates most of the details carved into my foam "rock" bases


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## Sammie (Oct 12, 2009)

I would suggest you contact "HX" here on the boards, the rock work he does is quite amazing. I'm sure he could help you with which materials to use.
He's from Finland but it's likely that the same products are sold in Norway as well.

Here's his website: https://planethx.com/


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## sparrow (Nov 14, 2015)

That website doesn't seem to be working for me. I was looking into DRYLOK some time ago when I wanted to do some scaping for aquarium and needed something fish safe, etc. But it's not found in Norway, from what I gather. And "fish safe" or any sort of safe paint/whatever seems to be very hard to come by. I found a sort of epoxy mix that was safe, some years ago and I still have it - but I doubt I will be using it because it was very hard to handle and you had to finish it all in like 30 mins or something. It was just too fussy.

Thing is, I want to use as little as possible of stuff, (grout/cement, drylok, masonry paint etc) - and more wondering if anyone has experience in using acrylics only on foam. I know acrylics with silicone stuck with coco fibre etc works, but I wonder if the acrylic paint will chip off/wear off without the silicone, or if it will stay. I might have a small diy drip system but I won't be having any water feature or animals. Only some misting to keep it a bit humid. 

I'm a fan of painting so I was hoping that painting a rock like feature would be enough withut having to fix it with some sort of mix of anything else, tbh. A sealant would be fine, but I would need to know what I'm looking for.


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## jgragg (Nov 23, 2009)

It might help people understand your needs if you tell what kind of animal, roughly. Frog, snake etc. I think one issue is that the expanded polystyrene is a little toxic and will leach chemicals into water. Having it perfectly encapsulated with a non-leaching, waterproof material like Drylok, epoxy, silicone cement, or whatever is important if there's to be much water loose in the cage. Acrylic paint is not a waterproof sealer. Especially with amphibians. In a dry terrarium, who cares? No water, no leaching.

I just went to HX's site that was linked earlier here. I got there no problem. See his "mudskipper paludarium reborn" video. He does *amazing* stuff, I'm glad he's still active with the hobby and also online. He was prominent - here, I think? - a long time ago. Maybe like 6-7 years?

Earlier replies to you match my experiences and impressions of grout, self-leveling cement, etc. I, personally, am done with that stuff - I like epoxy putties now (I figured out how to get along with it, now we understand each other and do nice things ha ha). Although I would add one thing about the concretes - there is a phase in the curing of concrete materials where you can sculpt it beautifully. (HX is a master of this!) Obviously, before it has gotten hard. And after it has stopped being so sloppy wet. But if you thought epoxy was fussy you may have similar feelings - this phase doesn't last long, especially if you've applied a thin layer of grout and it wants to dry really quickly. I learned to go a bit thicker, but then the weight really adds up. Tradeoffs...

Anyway, I gotta go eat breakfast with my wife. But I want to leave you with an idea or two:

1) In Norway you have a huge aquaculture industry, yes? I strongly suspect they have need of fish-safe, waterproof sealants somewhere. They must use epoxy paints (not putties - paints), or a Drylok substitute, now and then. That's one likely fruitful avenue to explore.

2) You have a human population that, like every other one, needs safe drinking water. So you have plumbing, water storage and delivery and treatment systems etc. Like all of us. Just like with the aquaculture people, the water managers MUST have need of - and access to - some nontoxic waterproof coating materials. OK that's another place for you to look.

Good luck, man. People here are kind and helpful, you've come to the right place.

cheers,
Jimi


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