Structural silicone

EDJFA

New member
I'm replacing a broken top brace on a 210g Oceanic tank. I checked with my LFS to see what they carried. They carry tank sealant. Not sure that's what is called for in this situation.

This is the piece that keep the tank from bowing, so it's got to be a strong joint. Will the typical GE silicone work or would you guys use something different? Or at the end of the day is silicone silicone.
 

jerpa

Team RC
Momentive RTV or GE SCS1200 are two I would recommend but you may be able to find other suitable structural silicones.

I would use the appropriate silicone for the job.
 

Daimyo68

Active member
Momentive RTV or GE SCS1200 are two I would recommend but you may be able to find other suitable structural silicones.

I would use the appropriate silicone for the job.
+1 Momentive is a structural adhesive.

Check you local Grainger, many keep it in stock
RTV103 is Black
RTV108 is Clear
 

jimmyj7090

aka John K
And the stuff at the LFS is most likely not an adhesive. Make sure to check the date codes on the RTV 100 series, sometimes it is sold past it's prime.

(I don't know how to decipher the date codes, but it's here somewhere in this forum)
 

wolfblue

New member
I'm a little lost by "structural", but I don't think 795 will be it. I use it for gasket type things where I would need to get it apart later. Sets up slow and if the tube is old it may just skin over and not set at all.

For all normal aquarium uses if your using Dow, use 732 in black or clear.

--John
 

sleepydoc

Team RC
All of these should have spec sheets that show the tensile strength and adhesive properties. That would be the best way to compare them.
 

uncleof6

New member
I have friends who have used Dow 795 with great success and swear by it over the Momentive RTV stuff for strength.

http://www.mcmaster.com/#7452A212 is the black stuff.

Dow Corning 795, is a neutral cure silicone. The same stuff that sparks all the controversy concerning GE Silicone II: the 'fabled' mildew resistant 'tank killer.' There is more contradiction in this hobby, than there is solid information...

In terms of strength, 795 tensile strength is irrelevant, as that is NOT what holds a glass tank together, rather it is the adhesive or "peel strength." The two (RTV100 series, and DC 795) are comparable and can be used interchangeably.

That said, Neutral cure silicone does NOT adhere to glass, as well as Acetoxy cure silicone, and is better suited for use with metals, etc. where the corrosivness of Acetoxy cure silicone would be a problem. This in and of itself, makes the RTV100 series the better, wiser choice. Really does not matter what your friends swear by.

The recommendation has been, and always will be:

1-part Acetoxy cure
100% silicone (no co-polymers such as acrylic)
FDA approved for food contact.
Suitable for the task at hand (adhesive to hold stuff together, sealant to keep water in, though an adhesive covers both bases.)

DC 795 does not fit that criteria, never has; never will. Some prefer what is "easier to come by," or cheaper, than what is actually best suited for the task at hand.
 

EDJFA

New member
I'm a little lost by "structural", but I don't think 795 will be it. I use it for gasket type things where I would need to get it apart later. Sets up slow and if the tube is old it may just skin over and not set at all.

For all normal aquarium uses if your using Dow, use 732 in black or clear.

--John
By structural I meant that it's not just holding a baffle in place in my sump. I need it to hold together so that 210g's of saltwater don't end up on my office floor and consequently the business below mine. That would really **** off the new neighbors.
 
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