# Creating an entire background using Great Stuff



## QHgal (May 18, 2006)

So, like the title says, is it possible? I've created backgrounds in my dart frog tanks with Great Stuff, and its safe for them. I want to seal the entire thing with drylock, just like the styrofoam backgrounds everyone else is building. I don't really have the tools to carve the styrofoam like I want it to look, so why not build the rocks with Great Stuff and then carve it into shape, just like the dart frog tanks?? Is there any reason NOT to use GS for a background?


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## mightyevil (Oct 23, 2008)

In my experiences, it is very hard to carve and shape great stuff but if you have done it before for dart frog tanks, then you may have a technique to be able to shape it easily. Also, drylok does not stick to great stuff like it sticks to styro, I think you will need to cement the background and then drylok it to be able to get the drylok to stick. What are your plans?


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## QHgal (May 18, 2006)

Well, I've built it and trimmed it to shape. I'm going to try the drylock on it tonight. Once its trimmed, the surface is rougher than if you just left it after it dried. I also put a couple of decent size rocks into the background for weight. I doubt it'll be heavy enough to not float, but once I get it into place, I think it'll be alright. I'll have to see how thick the drylock is before I know if I'm going to have to cement it or just seal it with drylock.

How thickly does drylock apply? Thick enough to fill tiny holes, or is it more watery? I haven't opened the can yet...


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## clgkag (Mar 22, 2008)

There is a great stuff foam made for ponds that is fish safe. One of the LFS here made their background in a salt tank by spraying the back with the pond foam and implanting rocks in it before it dried. Looks very nice.


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## mightyevil (Oct 23, 2008)

Drylok has almost the same consistency as paint so all the detail in the background will be visible. Yes, the top layer of great stuff is very hard to use Drylock on, so I am guessing you are removing all the top layer of the great stuff by carving it... what are you using to carve it? I don't think that the rocks are going to be enough weight for the background to stay down, if great stuff is as buoyant as styrofoam (and I think it is!) then it is going to float.


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## QHgal (May 18, 2006)

I picked up a can of Drylok last night, and this stuff is like water... I can't get it to stick to the great stuff unless I thicken it up with sand... Is that normal, or did I just get a bad can of drylok?


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## DanniGirl (Jan 25, 2007)

QHgal said:


> I picked up a can of Drylok last night, and this stuff is like water... I can't get it to stick to the great stuff unless I thicken it up with sand... Is that normal, or did I just get a bad can of drylok?


That's the normal consistency for Drylok. (Hence why it doesn't adhere well to "Great Stuff") 
Try roughening up the surface of the background.


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## QHgal (May 18, 2006)

Hmm, I didn't seem to have much problem with the styrofoam, even on the parts under the great stuff (I used broken pieces of styrofoam to lessen the amount of GS I needed to use for larger rocks), but on the GS itself, it just wouldn't adhere very well unless it was really thick. I might try to get some textured spray paint and spray the whole thing down with that, then seal it with drylock.


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## mightyevil (Oct 23, 2008)

I told you so... :roll:

It is not a big deal, just buy some cement and do a very light coat of cement on the parts where the Drylok is not sticking. Then you can go over it with Drylok and it should stick...

You know what? If you have any areas where you have the the top layer of great stuff (you know, the hard shiny layer when great stuff dries...), you might want to take some rough sandpaper and give that some texture. In my experiences cement and Drylok will both fall off in those areas if fish poke at it or if you accidentally rub against it or hit it when doing maintenance and then you have the ugly yellow layer visible.

I hope everything works out!


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## DanniGirl (Jan 25, 2007)

mightyevil said:


> I told you so... :roll:
> 
> You know what? If you have any areas where you have the the top layer of great stuff (you know, the hard shiny layer when great stuff dries...), you might want to take some rough sandpaper and give that some texture. In my experiences cement and Drylok will both fall off in those areas if fish poke at it or if you accidentally rub against it or hit it when doing maintenance and then you have the ugly yellow layer visible.


+1


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## DanniGirl (Jan 25, 2007)

Double post


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## QHgal (May 18, 2006)

You said drylock wouldn't stick to the shiny parts, and I carved all of it, so there are no shiny parts, its all rough and textured, sanded and all that jazz. The drylock will run off of the smooth edges, I already had that figured out, so I sanded everything. My problem was getting the drylock to actually put color on the foam without looking like I put a very light layer on it. I got some Krylon Fusion spray paint and sprayed the entire thing, then repainted with thickened drylock and it worked. Its like the drylock was too thin and just sunk into the GS, wouldn't actually color it.


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## mightyevil (Oct 23, 2008)

In my first post I said it wasn't going to be easy to put Drylok on Great Stuff (in general). The way you do it is not as easy as with styrofoam. You have to put many layers of Drylok on GS to make it stick, the GS will soak the Drylok in but you need to let it dry and then put another coat on it and repeat this until the Drylok stays on but that doesn't matter anymore, you figured it out! :thumb:

Got any pictures? We would love to see the progress opcorn:


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## QHgal (May 18, 2006)

I didn't take any pictures of the build, cause I wasn't sure it would come out. Now that it looks like it just might work, I'll take some pictures tonight LOL

It was surprisingly easy, tho... I've used GS in my dart frog tanks, so I was familiar with carving it. I tried to start with styrofoam, but the only thing I had available to cut with was a jigsaw, and after the 3rd piece it made my hand go numb, especially on the pieces already glued together with gorilla glue.


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