Silicone or epoxy...?

kass · Post by **kass** » Tue May 09, 2006 12:06 am

Yea, I was thinking of using some very small gravel, maybe even sand. Just something for a more natural look, instead of the transparent plexiglass.

YBeNormal · Post by **YBeNormal** » Tue May 09, 2006 12:35 am

How soon are you planning on starting this project? I have some acrylic scraps and can test with silicone and some other ideas but it would have to be be later this week or on the weekend.

kass · Post by **kass** » Tue May 09, 2006 1:43 am

Well I cut out the acrylic pieces today and am just waiting for my order of weld-on cement to come in. I think tomorrow maybe I'll test it with silicone. The website where I got the idea for the paludarium said they used silicone to stick rocks to the divider.
http://filebox.vt.edu/users/efalwell/pa ... arium.html
The rocks looked fairly large. I'm going to email the author of the site and see if they had any difficulties with it.
Thanks a lot for the offer. I dint see how the silicone would not hold very small gravel, but I have no experience at all with it, it just seems do-able.

Post by **RTR** » Tue May 09, 2006 11:40 am

I have used silicone to hold gravel to glass strips for terraces, but not to plastic. I prefer epoxies for the job, but it a bit tricky.

YBeNormal · Post by **YBeNormal** » Tue May 09, 2006 9:17 pm

Yeah, epoxy is one option and would work great. Smelly, nasty to apply and not real cheap are among the drawbacks that come to mind though.

Krylon paint is safe to use in aquariums (people use it in reef tanks!), adheres to glass and plastics and makes a decent base for silicone. I'd probably try that instead of silicone directly on acrylic. JMHO

kass · Post by **kass** » Tue May 09, 2006 10:21 pm

Is the krylon a spray paint? And are you suggesting applying it to the acrylic and then silicone the the gravel to the krylon covered surface?
Is there a certain type of epoxy to use that is aquarium safe? or just any epoxy resin?
I tried the silicone and weld-on cement to attach the gravel and so far it hasnt worked out well at all. The silicone doesnt even really stick to the acrylic very well. Do you think it will work to seal the acrylic to the tank, which is glass?

YBeNormal · Post by **YBeNormal** » Tue May 09, 2006 10:59 pm

Is the krylon a spray paint? And are you suggesting applying it to the acrylic and then silicone the the gravel to the krylon covered surface?

Yes and yes. No guarantees but I think it would work. This is one of the tests that I would have done later this week.

Is there a certain type of epoxy to use that is aquarium safe? or just any epoxy resin?

I have no experience using epoxy in or on aquariums.

I tried the silicone and weld-on cement to attach the gravel and so far it hasnt worked out well at all. The silicone doesnt even really stick to the acrylic very well. Do you think it will work to seal the acrylic to the tank, which is glass?

As I expected and no, not very well. Silicone can be used to hold an acrylic tank divider in place in a glass tank or sump but you have to use lots of silicone. The silicone sandwiches the edge of the acrylic sheet and sticks to the glass, not so much to the silicone.

Maybe there are some other options that will work. Can you provide a drawing or post a link to the design you are working on?

Post by **RTR** » Tue May 09, 2006 11:54 pm

The epoxy I used is the same as used in stained glass work, and I do not remember the brand. Glass studios should have it for bonded panels. It is clear, but is intended for glass, I do not know if there a formulation suitable for acrylic.

kass · Post by **kass** » Wed May 10, 2006 12:24 am

Here's a quick sketch...

Brown is land and blue is water, obviously.
The "empty space" and the river, on top of the empty space, is where I want it to be "waterproof". The other land area is going to have the filter (fluval 2+) and heater. This will just be wedged in place so I can remove it to access the filter and heater. The underwater wall of the land where the heater and filter will be has many holes in it for water movement.
I have cut out all the pieces and glued most of them together, which the cement did a great job of doing, but the cutting was a PITA, I used a little hand tool to score each piece out... kept me busy for MANY hours.
I want to stick the gravel to the ramps leading onto the land and the land area above the filter/heater.
Sorry I cant get the pictures any bigger... i drew them on Paint, i don't have another program to do them on. The empty space is the white area under the larger land mass on the right of the tank.

YBeNormal · Post by **YBeNormal** » Wed May 10, 2006 1:33 am

Sounds interesting and the pics work fine for this discussion. We will expect high quality camera pics of the finished product though.

If the land area(s) on the right side will be fixed in place and you want the underside to stay dry, silicon should work OK for that if you apply a heavy bead where the acrylic meets the glass. I would either make completely sealed box(es) though or at least place another piece of acrylic underneath on the right side to support the weight of the "land" area. As you noted, silicone barely adheres to acrylic and won't support any weight or lateral movement.

I decided to go ahead and set up a quick test. We already know that silicone will stick to glass, sand and gravel and I have little doubt that it will stick to surfaces painted with spray paints such as Krylon. The real question is how well spray paint will stick to acrylic. I painted the backside of a 75g tank a couple of days ago. Since it is cured and handy, I applied a bead of silicone to the paint tonight. I also spray painted a small piece of scrap acrylic. I will check the silicone and the paint tomorrow evening and let you know the results.

kass · Post by **kass** » Wed May 10, 2006 1:53 am

Yea I was going to have weight barriers under the right side land mass, probably rows of acrylic, as I have a lot of extra.
Thanks a lot for all the help!
I will for sure post pics when it is all done.

YBeNormal · Post by **YBeNormal** » Wed May 10, 2006 2:01 am

Quick interim update:

The thick silicone bead on the painted glass is barely skinned over and already feels like it has a firm grip on the paint. The paint on the acrylic is still not fully hardened but I could not scratch it off with a fingernail. So far so good.

I think this combination will work but will give you a final answer tomorrow. If it works, you might even be able to find spray paint that is close to the color of your sand and rocks!

kass · Post by **kass** » Wed May 10, 2006 6:06 pm

The silicone I have is black, which was kind of disapointing as it didnt even say on the package (unless I missed it) and the picture on the back shows it comming out as white and it is made by all-glass aquariums so I just assumed it would be clear. So i guess the spray paints colour would not matter.

YBeNormal · Post by **YBeNormal** » Wed May 10, 2006 8:25 pm

I would gladly take the black silicone off your hands if you were local. Oh well...

OK, the test was a total success. Paint stuck to the acrylic and silicone stuck to both the painted glass and the painted acrylic. I think painting the acrylic and using silicone would be your best and cheapest solution.

kass · Post by **kass** » Wed May 10, 2006 8:30 pm

Sweet! So you used krylon paint right?

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Silicone or epoxy...?