Good adhesive for gluing rock formations.

[windmill]

I'm going to build a tall rock formation for my 47 gallon pillar and I want a safe, strong adhesive that will hold the rocks without worry of release and won't discharge harmfull stuff into my soon-to-be seahorse tank.
I've used silicone in the past with decent results, but I was building a simple "cluster" of rocks, not an actual tower. For those that haven't used it before, silicone is pretty flexible and not very strong when bonding very porous pieces. It'll let go if you pull very hard and will twist and sag if any stress is put on it.
Like I typed, I'm planning on building a "tower" type structure and would like some ledge-like things at various heights. I'm sure silicone will not be ideal for this purpose and am looking for a better adhesive. In my line of work, we have many different types of adhesive for many different applications. The strongest and most permament of these adhesives is called 5200. It's a high strength polyurethane formula for above or below waterline applications. Primarily used to seal and provide extra adhesion to underwater parts like propshaft logs, rudder ports, and thru-hull fittings on large, inboard boats. I think this stuff would be perfect.
Now for my concern, is it safe/non-toxic? It doesn't say anything about mildew repellant or having any additives. The only warning is eye and skin irritant and to those who are sensitive to isocyanates. Contains - urethane prepolymer, talc (may be the coloring), titanium dioxide, zinc oxide, diethylene glycol monomethyl ether acetate, fumed silica, alkyl isocyanate silane, toluene diisocyanate, toluene, and hexamethylene diisocyanate. Everything a growing boy needs. Any ideas suggestions, anybody use this stuff before?

 

[chipmaker]

There really is not one.....Only method that I would trust to retaining all the pieces in place is to stack the rock how you want them and start to pin them together with plastic rods. Stack em up, then de-stack em keeping them in order as to how they go. When yu get back down to the lower rocks, use a drill and a long drill bit (reg HSS will work or a masonary bit) and drill right through them all. and insert a plastic rod. Stack some more up and do the same thing. You can buy plastic rods from hobby shops, or look around in places like wally world, and you can find lots of stuff that will work. I use the plastic welding rods used with hot air plastic welders, and you can buy a pack of about a 100 for about 3 bucks at harbor freight. Once its all stacked and driled and pinned only the top rocks will have any holes showing and they are easily filled in with sand or live rock rubble pieces or stick a shroom over it......To much messing around with glues and epoxies. Drilling and pinning is fast and easy.

 

[f14peter]

Another option is to use plastic zip-ties to lock the rock pieces together.
I understand 0ver time they'll get covered with coraline and/or algea and become virtually invisible.

 

[patandlace]

I would use zip ties and epoxy putty. It should be strong enough and is non toxic for sure.

 

[windmill]

I was hoping someone would have some experience or prior knowledge with 5200. I'm thinking, if this is non-toxic, it'd be perfect.

 

[fgcu14]

My LFS carries something called Reef Glue for that purpose. I've never used it but it may be something you want to check out.

 

[chipmaker]

Unless thre rock is scrubbed free of any loose junk coraline included, its not a very good joint no matter how strong the adhesive used may be. The bond is only as good as the substrate its adhered to, and live rock tends to be pretty darn weak if your looking to achieve a strong bond. I do not think I would want to set there looking at nylon tie straps either waiting for them to get covered with coraline. The 5200 adheswive you mention is like scotch or 3M 5240A, from what I can tell. It probably will be fine in regards to toxicity, but its still something that is way stronger than what is being bonded, so its really a false sense of security in how and what its actually holding together.
Thick thixotopic putties also generally suck at adhering rock or corals since most apolications do not penetrate into any pores etc of the rock sufficiently due to the viscosity of the epoxy so it is also adhering to a weak substrate surface as well.

 

[rappa]

Doesn't that 5200 take like a week to dry? Plus you would have to clamp things together. I would think you would want something that dries quick? I have used that stuff before, and really didn't like it. It bonds great, but just too long to dry. You could try black windshield urethane. It will dry within a day and gets very hard. It bonds great. I bet when it is fully cured, it wouldn't release any contaminants. You can get it at NAPA.

 

[windmill]

The 5200 i'm talking about is 3M brand. And yes it does take about a week to fully cure, it's usually tack-free (dry) within 24 hours though. I'm planning on using the fast cure formula which is supposed to fully cure in no more than 48 hours. We also have some other stuff by 3M called 4200, i'm going to read up on that stuff and see if that might be better. There some stuff called "Life-Calk" that we carry too, I think it's a universal sealant that can be used in windshield installations too, I'll check on that one as well.
Appreciate the responses and feedback.

 

[windmill]

Alrighty-then.
The Life-Calk is nixed as it's a thiokol LP polymer based rubber compound requiring 1-3 days to be tack-free. Plus it's black. It's a toss-up between the 4200 and 5200 fast cures. Both chemically react with moisture to cure (can cure underwater) and both are sandable and paintable. I'll likely go with the 5200 because it looks like the only difference is strength - and price.
So, for now, that's my decision. A tube of white 3M 5200 fast cure to be used to glue my rock formations. Anybody curious if this stuff will eventually kill sealife just look for my name and my eventual thread on my 47 pillar w 55 sump to be stocked with seahorses. I'll be on here freaking out if it's not safe.

 

[bojik]

A substance that might work and is readily available at many car parts/hardware stores. Quick steel, I have used it with success on some applications requiring creative adaptation of submersed filter pipes and such. It is rated safe for drinking water tanks and pipes. Good for a quick patch on a gas tank too. It will harden enough to be drilled and tapped. Cures in about 10-15 minutes. (longer if under water). This stuff. http://www.vintagetractorspares.co.u...new_page_1.htm
I assume its much like the putty they sell for aquariums for the purpose your looking for.
Stack the pieces where they sit at least moderately stable as you go up and adhere each layer. Let each stacking cure before adding the next sections.
Good luck with your project.

 

[sharkbait9]

I know a LFS that used "great stuff" to put all the rock together around the over flows and what not. Fish and coral never seemed to have a problem.
The next time i'm by i'll stop and find out. I'm pretty sure its great stuff.

 

[wattsupdoc]

I've used that "great stuff" on a lot of things around and IN my setup. I dont believe it has any ill effects, it does cure under water, it bonds really strong and rerally is great stuff. I believe it's pretty much the same product as weld on #16 (methylacetatolulene or sometin' like 'at)but doesnt contain any acrylic resin.

 

[1journeyman]

I'd go with the rod idea...
I just had a 3 inch piece of live rock crack lose and fall to the bottom of my tank a couple of weeks ago. The only thing it had growing on it is Encrusting Gorgonia.
My point is; as was posted earlier, live rock really isn't that strong.

 

[chipmaker]

Originally Posted by wattsupdoc
I've used that "great stuff" on a lot of things around and IN my setup. I dont believe it has any ill effects, it does cure under water, it bonds really strong and rerally is great stuff. I believe it's pretty much the same product as weld on #16 (methylacetatolulene or sometin' like 'at)but doesnt contain any acrylic resin.

Great stuff is far from being the same as Weldon 16. Great Stuff is expanding polyurethane foam. YOu can also get self expanding foam in black color. Look in the ponding section of big box stores etc. Its commonly used to seal gaps etc in rock work for water falls in koi and gold fish ponds, but it has a bad habit of letting loose in those situations just the same. Its main intended use was to fill gaps but folks started to use it to actually adhere rocks etc together like motar is used.

 

[windmill]

I appreciate all the suggestions.
I'm giving the 5200 a try first. I'll try anything at least once, so here's my go.
Well I stacked my rocks (NOT LIVE) to a beautifull formation last night. Didn't use any glue and everything was oddly stable. I used a TV dinner tray as a platform and placed the rock on a piece of egg-crate (that is the plastic square things that are commonly used in office fluorescent light fixtures right?). I stacked it up about 22 or so inches using about 15 pieces of base rock with wonderfull ledges and caves and overhangs. I shook the tray and pushed on different sides of the assembly and to my surprise, it didn't budge at all. So I think I can re-assemble it in my tank just the way it was sitting on my tray......yeah, that was a dumb idea. I had to re-dry the rock and stack another tower. So I did, and it looked damn good, very similar but a little better in my opinion; more rocks and more overhangs. Then I opened that fast-cure 5200 and squeezed a bead around each rock connection, pushing bits into crevaces and all. I did it in my bathroom because that 5200 likes heat and humidity. Finished up the majority of the tube then eventually went to sleep.
So I wake up this morning and poke the bonds to see if it's hardened up. It has for the most part, but you can tell it still has a little ways to go. Tugging on one of the top rocks felt like the bond was satisfactorily strong, definately stronger than silicone. When I get home from work today, i'll check it further and let ya'll know how it works.
One thing I've been worrying about is how the hell am I going to get this enormous mountain of rocks into my tank. Everything is now glued together and I might have to break the bonds halfway up to make two seperate pieces. I mean the whole structure probably weighs 30-40 lbs out of water, and as I mentioned earlier a little over 22 inches tall by probably about 10 wide and 16-18 long. How am I going to delicately lower this thing into my 30" deep aquarium? I don't think the 5200 will hold the weight of the rocks if I lift the whole structure by the top......I'm going to need a ladder, and some rope and pulleys.

 

[windmill]

Well sh!&.....The 5200 did amazingly well at bonding slightly wet tuffa rock together. Some spots felt solid and others let go at the first tug, which I should have expected, too much variance between one rocks texture and another's.
So I was banging my head against a wall for the majority of sunday morning trying to figure out how in the world I was going to lift the 40 lb monstrosity. The only feasible way was to tie strings around the milk-crate thing the structure was sitting on and lift from those. So I had to get a screwdriver to pry up a corner, thread some string under it, and repeat for all 4 corners. I was fairly confident it would work, the string was strong, the rocks were fairly stable....I was ready to go. I lift it a few inches to see how stable it is and notice the strings are pulling and putting pressure on certain rocks (the rocks protruded a lot from the edges of the milk-crate), one rock slides a little bit and the structure is heavier than I anticipated. So I slowly lower it back onto it's tray and as soon as it has to support it's own weight again, it falls apart. So I start cussing and get pissed off.
Anyways, tank is still empty, most rocks are broke and back in their worthless buckets. I'll give it another go eventually and hopefully break my goddamn tank so I don't have to pull out any more hair.

 

[chipmaker]

Well its not like you were not warned........
"Unless thre rock is scrubbed free of any loose junk, coraline included, its not a very good joint no matter how strong the adhesive used may be. The bond is only as good as the substrate its adhered to, and live rock tends to be pretty darn weak if your looking to achieve a strong bond
"My point is; as was posted earlier, live rock really isn't that strong."

 

[wattsupdoc]

Originally Posted by chipmaker
Great stuff is far from being the same as Weldon 16. Great Stuff is expanding polyurethane foam. YOu can also get self expanding foam in black color. Look in the ponding section of big box stores etc. Its commonly used to seal gaps etc in rock work for water falls in koi and gold fish ponds, but it has a bad habit of letting loose in those situations just the same. Its main intended use was to fill gaps but folks started to use it to actually adhere rocks etc together like motar is used.
OOOh DUUUUH!

What was i thinking? :notsure: That stuff wasn't great stuff. I dont know why I said that. Now what was that stuff called? :notsure:
OH yeah Seall All!
It really is "Great Stuff" though!!

 

[wattsupdoc]

Being as alot of people make Lr outta concrete mix, I'd say you could use a good mortar mix and build it on a piece if plywood , then get someone to help you lift it into the tank. If it's allready full of water then the rock will become bouyant and you will be able to handle it better in the water. The plywood wont sink very well though.

You're gonna have to have some help regardless though. Also, I've tried this before with my previous cichlid setup. The problem i had was when the rock entered the water, the water immediately began penetrating the gaps between the rock and sealant and it fell apart allmost instantly.

I gave up after the 4th try.