Silicone Comparison

[Mr. Maingano]

There are always a number of threads wondering about the best silicone to use for tank building and/or reseals.

My question is slightly different. I am looking at possibly resealing a 4' (120 gallon) tank and have 2 brands in mind. They are used by tank builders here in Canada and I want to use the same. I will only purchase Momentive RTV 100 Series or GE SCS1200. Please do not cloud my thread with suggestions of other brands.

What I am wondering is....

When comparing data sheets (I have printed them for comparison), what are the most critical qualities (tensile strength, etc.) to compare?

I appreciate your feedback.

 

[Ulu]

Shear strength vs elongation is the real clue. Some formulas are twice as strong as others, and others stretch much more.

A window needs some stretch, becuse buildings move a lot. You don't need much stretch (elongation) on a tank. A tank isn't supposed to expand and contract because the temp is always constant.

But high shear strength is desirable.

The only real things to be concerned with here are:

- clean, clean clean glass
- correct joint geometry
- adequate curing time without movement or temp changes

And one fourth thing. Test each tube.

I've been buying silicone since the early 70's, and after all these years I finally got a bad tube.
I used it to glue up a small mirror and it didn't cure at all. A week later samples I shot were still gooey.

So, a day beforehand, open the silicone and shoot some on a scrap.
If it's hard the next morning, start wiping the glass down and shoot some glue!

I just had to clean goo off my windshield and a mirror, but imagine if I'd had to scrape goo off an entire tank twice because of bad silicone.

Ritual suicide would be considered . . .

 

[Mr. Maingano]

Anyone else care to chime in?

Are shear strength and elongation all that need to be considered?

 

[Lepisosteus]

they are all critical qualities. Cure time to tensile strength, all will play a role in the outcome of your reseal.

For resealing, the most important attributes in my opinion are cure time, work time, shear strength, tensile strength. The others are more important if you understand the fluid dynamics of an aquarium (elongation, joint movement etc).

And one fourth thing. Test each tube

This is good advice. Some silicones never cure

 

[Mr. Maingano]

Great. Thanks to both of you.

As it turns out, it looks like I won't be doing the reseal after all.

I just picked up a 135 gallon in beautiful shape for $200.

So stoked.