Silicone sealant on acrylic?

[ChristineB]

I read silicone doesn't bond well to acrylic, but does anyone have experience with this? I know better than to use it on a structural or load-bearing seam, but I was hoping to use it to seal on a substrate. I have a thin foam textured aquarium background that I want to use as a substrate, and if silicone is only semi-permanent that's actually better for my purposes; a 50-gal acrylic tank is a pretty big investment and I hope it will outlast the substrate, so if it peels off with a little effort, that's ideal.

Follow-up question: Where does one buy gray silicone aquarium sealant? I've seen a couple references to it on here but my Amazon search just turns up black and clear. Any brand recommendations?

Thanks!!

 

[Chinadog]

Acrylic sometimes does weird thing when it gets wet. I have some sliding acrylic panels that cover my tanks that can warp and sag when they get condensation on them. Also, my usual method of using silicone to glue a marble to the sliding glass lids as a handle won't work on acrylic, it just peels off for some reason.
Regarding the gray silicone, you might have more luck searching for r.t.v sealant or r.t.v silicone, it just stands for 'room temperature vulcanising', but that's what its known as in most industrial applications so you might find gray stuff that way, just make sure it doesn't contain anti-mould chemicals.

 

[mr cyclone]

If Acrylic is Perspex , Then no!. I used it for a divider in my tank and the water burst the seal and flooded my terretrial area,School boy mistake,But isnt too easy to get cheap glass for fish tanks.
Glass is the best option if makeing a 50/50 . I am away to try just using expanding foam to see if this will make a good divide between land and water

 

[ChristineB]

Thank you! I checked around and could only find mold-inhibiting silicone in gray. I found mixed reviews from fish hobbyists whether the "GE Silicone II" is safe; it says 100% silicone but then does have a couple additives (potential issue with "petroleum distillate"?) and one person felt it hurt their tank, so I just played it safe and got standard clear aquarium silicone.

I used it to fill the gaps around a textured substrate that's already pretty wedged in there; I'm not sure if it's going to be watertight but at least debris won't get in there. It looks pretty good despite my crummy smeared seam. I will post some pics as I set it up. Still got over 45 hours of waiting! :grin:

 

[JoshBA]

If Acrylic is Perspex , Then no!. I used it for a divider in my tank and the water burst the seal and flooded my terretrial area,School boy mistake,But isnt too easy to get cheap glass for fish tanks.
Glass is the best option if makeing a 50/50 . I am away to try just using expanding foam to see if this will make a good divide between land and water

I had the exact same thing happen to me. Using sandpaper may help, but the best option is to go with glass. I ended up using the really cheap, super thin glass for a divider, and it seemed to hold up pretty well with lots of silicone.

I've seen several successful builds utilizing polyurethane foam as a divider.

 

[Dyelon]

If your looking to bond acrylic to acrylic, dichloromethane will fuse two pieces together. It works very well and very quickly and is pretty much permanent.