How to glue dry rock together?

[Kinetic]

What do I use to glue rock together? I want to create some fancy smancy rock formation with my marco/reeferrock, but aside from balancing them with skills of a circus performer, I'm not sure how to.

I know I may be able to drill through the rock and use an acrylic rod... but that seems really difficult getting the right angles, especially for smaller pieces.

I have some of that epoxy that's green on the outside, grey on the inside, that I once tried to use for frags (later reverted to super glue gel). Will that hold up?

This will be in an entirely dry environment.

Thanks!

 

[Al G Blenny]

Use spray foam. Home Depot has it for about $5 a can. I think it's called Great Stuff.

 

[fishnfst]

I think that the epoxy will work fine.. They make grey as well.. IT should hold quite well on dry rock...

 

[Kinetic]

<a href=showthread.php?s=&postid=10027906#post10027906 target=_blank>Originally posted</a> by Al G Blenny
Use spray foam. Home Depot has it for about $5 a can. I think it's called Great Stuff.

Sounds interesting. Do I just spray it on and it'll harden? That'd be neat to balance or hold the rocks on top of each other, spray and let dry. Any experience with how fast it holds?

<a href=showthread.php?s=&postid=10027909#post10027909 target=_blank>Originally posted</a> by fishnfst
I think that the epoxy will work fine.. They make grey as well.. IT should hold quite well on dry rock...

Ok I'll try this one too. I remember once it dries, that stuff is pretty darn hard.

Anyone also try to flatten the bottom of rocks so they don't create pressure points?

 

[dots]

Pin it with the rod which will limit most of the degrees of freedom. Then you can use a minimal amount of epoxy to "lock" it down. By using a little epoxy this way and pinning it, you can modify it easier later on.

 

[fishnfst]

I never thought about spray foam.. I didn't know it was fish or reef safe.. That stuff is super strong though... At the Hilti dealer in SF they have cans of it embedded in the foam and you can't get it out.. Its expanding though.. If the pieces aren't secure the foam will just push it apart.. I've seen it push sheetrock out on walls it was sprayed into....

 

[Al G Blenny]

Epoxy isn't adhesive so I don't recommend using it to hold rock together. You can only really use it to prop things up. I let the spray foam sit overnight.

 

[GreshamH]

Spray foam is NOT UV stable in will break down in the slightest of UV amounts.

Use Thorite or Hyrdrolic Cement. It's your strongest option and it's easy to use. If you want more info, email me and I'll tell you all about it. FWIW, you can find it in the specialty cement section of HD. It's in a yellow 10 pound bucket and it's called water plug IIRC. Just let it air cure for a week and your golden. If you want to see an example online, Sanjay's build thread has a great example and same with the thread in the ADvanced forum call "reef Ceramics"

 

[GreshamH]

<a href=showthread.php?s=&postid=10029811#post10029811 target=_blank>Originally posted</a> by Al G Blenny
Epoxy isn't adhesive so I don't recommend using it to hold rock together. You can only really use it to prop things up. I let the spray foam sit overnight.

Depends on the epoxy really. Epoxy resin has plenty of bite to it, while putty epoxy (plumbers) has none

 

[GreshamH]

BTW, use fiberglass rod, not acrylic. Acrylic becomes brittle and will collapse at some point. I did a tank like that for a customer (on their request) and it lasted about 3 years before the rod started to fail and drop rocks.

 

[Al G Blenny]

<a href=showthread.php?s=&postid=10029838#post10029838 target=_blank>Originally posted</a> by GreshamH
Depends on the epoxy really. Epoxy resin has plenty of bite to it, while putty epoxy (plumbers) has none

You are right. I just assume people are talking about the putty.

 

[GreshamH]

After rereading the thread, Art definitly indicated it was the plumbers putty he was using, so I guess I was just being Mr Symantics Guy, sorry

 

[Kinetic]

<a href=showthread.php?s=&postid=10029904#post10029904 target=_blank>Originally posted</a> by GreshamH
After rereading the thread, Art definitly indicated it was the plumbers putty he was using, so I guess I was just being Mr Symantics Guy, sorry

nono symantics guy is definitely helpful nevertheless! I appreciate the thorough responses, you guys really take your time to help others!

Now I know what to use. I'll probably goto home depot for that cement stuff.

Thanks!!

 

[GreshamH]

Check out the "Reef Ceramics" thread in the Advanced Forum. Mr Wilson has some great info on it. Also do check out Sanjay's work. He made some awesome pillars.

Tom (Sparkss) used the fiberglass rods if you need advice on those

 

[dots]

My rockwork is lucky to stay as is for 6 months because I get bored with it, so the whole brittle thing I don't know much about, I would assume that it is from saltwater breakdown if any.

Im curious and would like to hear more on this.......if thats true is that the same for acrylic tanks and sumps made from the same stuff? This is the first I am hearing this.

Could the rod have been supporting too much from the get go and was snapping over time, this would be my first thought....

They "epoxy" I am speaking of if the two part stuff that we all use to attach corals.......not the Hardware store stuff, speaking of which, I would be leary of the foam of how stable it would be in the water and what it could leach into the water.......perhaps over time and after a good flushing....but for an existing tank........

 

[Al G Blenny]

The acrylic rods do get brittle. I have seen it also. I think it might be because they use a different type of acrylic than the types used to make tanks.

The two part stuff is the same as the stuff found at Home Depot. It works just the same.

Lots of people have used the foam and it works great. Not to mention Kinetic said he is looking for an answer for attaching dry rocks. He didn't say it was for an existing tank. Never the less it does work great.

 

[GreshamH]

Epoxy resin + acrylic rods is what we used on the tank. Two part will seperate over time when holding liverock. Wayne Shane can vouch for this as will my old boss.

Arcylic rods are not the same acrylic used in our tanks. We use cast, it's extruded. Extruded has the entire surface area under tension, and can absorb water, making it brittle fairly quickly. Our sumprs are cast, as are our tanks. Cast has no real surface tension and does not allow water to be absorbed.

 

[fingerwrinkles]

Definitely use fiberglass rods (recommend 3/8") as your main supports but be careful when cutting (noxious dust) and be sure to wear gloves and sand the ends after cutting (glass shards will get in your skin much like touching a fireworm). Dowel the rocks using a standard mortar bit on a plug in drill (battery powered drills tend to run out of gas fairly soon if you hit a tough patch of rock). Use the epoxy or mortar to bind the rocks together after they've been doweled. You can get some really amazing formations with this method (I'd post a photo but don't have anything small enough). Don't use the mortar / epoxy just by itself if doing anything other than stacking, as the binding agent may hold but the LR itself will decompose after time.

 

[GreshamH]

Good point.

Ever hear about that huge aquarium in Chicago that was built using several tons of live rock stacked on each other? Rock collapsed under the weight and broke the tank. IIRC there is a product liability suit over that one, but that is not for me to even speculate about

 

[dots]

Yeah I agree on the epoxy.....Ive seen it myself and use it mainly for a saddle and try to line the centers of gravity and let the rocks themselves do most of the work......the rods and epoxy, at least in my case, are not under large loads. I use both sparingly.....but then again am not into making grand arches and only have a 75g, which means I don't have 300#s to need to deal with. Just stacking a few in a column.

In fact, with the cube I am planning on getting I am planning on a minimalist approarch and have no rock stacked.....rather select tall pieces or make them myself that are single standing structures.

I am ultimatly wanting something like CWARD's tank with large rare pieces that are the focus.

http://reefkeeping.com/issues/2006-10/totm/index.php

I hear what you guys are saying, I think our applications are different for the two materials. Thanks for the heads up!!