Silicone sealants in enclosures

[teddywilson]

I’d like to hear from people who have either actually studied on or have personal experience using different types of silicone sealants in reptile enclosures.

We all know that aquarium marketed silicone as well as silicone I are safe- however are others actually dangerous or is it simply unknown?

Almost a decade ago I accidently used silicone II to reseal an aquarium that I then housed 3 fire belly toads in. The aquarium is filled halfway with water. I didn’t realize my mistake until months later when going to get some silicone for another project, I hadn’t thrown out the tube I used for their tank and then realized it was type II not I.
I hadn’t noticed any affects, all three toads appeared happy and even the few fish in the tank were unbothered.
Today, all three toads are alive and well in that same aquarium (the fish ended up being eaten at some point).
I always see people saying how deadly silicone II is- but in my own experience that doesn’t seem to be the case. I have used silicone II in several of my reptiles’ enclosures now for years with no ill effects- but I also allow at least a full month for curing.

Thoughts and experiences?

[armiyana]

From what I remember, Silicone 2 is more likely to have additional ingredients for mildew and mold resistance. It’s a matter of tracking down the information on it and checking if the label says it should not be used in aquariums, ponds or drinking fountains. Not every brand of Silicone 2 is safe

If it is indeed 100% it shouldn’t be an issue as long as it’s cured properly. The acid cure properties in Silicone 1 have the fumes that dissipate when it’s done, 2 doesn’t. It may lead to uncured silicone in the seams in the aquarium and easier to damage later.

[caryl]

@armiyana

Silicone 2 is more likely to have additional ingredients for mildew and mold resistance.

That’s my understanding as well from what I remember back when I was teaching chemistry. I don’t remember the specifics about what gets added to various proprietary formulas, nor is all of that info necessarily public as there are patents for specific brands. Chemically, the silicone itself is the same. It’s the rest of the ingredient list which can be problematic. Even if the product is not considered food and animal safe, problems may not be immediately obvious. Some things may be immediately lethal while others are carcinogenic or impede reproduction of certain species.

Here’s a handy trick. There’s an easy way to know if the product is food-safe, which means it’s made without compounds known to be harmful to humans, which is also aquarium and vivarium safe. Take a bit that’s dry and stretch it. If it looks blue, it’s food, aquarium, vivarium safe. If it looks white, it’s not.

[socraticmonologue]

There’s no reason to believe that any cured silicone sealant will have any acute toxic effects on any herp. There’s also no reason to believe that any cured silicone sealant will have any confirmed chronic toxic effects on any herp; that would take epidemiological data that really isn’t available. Neither of those facts, though, entail anything about which products are safe, safer or safest.

But there are plenty of known facts that can help make the choice, and a lot of hobby claims don’t correspond very closely to those facts.

GE Silicone 1 (which is an example of an acetic cure sealant) and GE Silicone 2 (which is an example of a neutral cure, AKA ammonia cure, product) both contain mold/mildew inhibitors (at least as of the last time I know about that someone contacted them about it). So that’s not a deciding factor.

One reason products like GE 2 are not safe for aquatic applications is that they release ammonia while curing, and ammonia is acutely toxic to fish and other aquatics. A search of the aquarium forums can pull up a couple such reports (I’ve done this in the past). Acetic cure products (of which GE 1 is an example, as are all silicone sealants marketed as ‘aquarium safe’) don’t have this problem.

One aspect of aquarium-marketed silicone sealants is that they (in contrast to at least some other silicone sealants) have been tested to be suitable for underwater applications. This may or may not be relevant for a particular herp use.

Another aspect of aquarium-marketed silicone sealants is that they tend to (i.e. this has been true among the products I’ve dug into the SDS sheets on) avoid more toxic siloxanes such as octamethylcyclotetrasiloxane. Siloxanes are the basic chemical compounds that constitute the ‘silicone’ part of these sealants; contrary to widespread claims, it is simply not true that the silicone itself is the same in all silicone sealants. It is also irrelevant whether the label claims ‘100% silicone’, since that simply refers to whether the silicone was augmented with latex or some other sealant; though all ‘aquarium safe’ sealants I’ve come across are indeed 100% silicone, this factor cannot be used to judge their appropriateness.

The most pressing reason, IMO, to avoid all neutral cure (e.g. GE 2) silicone sealants is that they all use organotin curing agents. These compounds are known endocrine disruptors, carcinogens and teratogens (I’d post some links but a general web search will give months of reading material).

@caryl

There’s an easy way to know if the product is food-safe, which means it’s made without compounds known to be harmful to humans, which is also aquarium and vivarium safe.

The connection between ‘food safe’ and safety for animal use isn’t that direct, and there are some easy counterexamples (such as copper cookware, which would kill marine inverts kept in it; also chemical treatments of certain foods that would kill a range of animals, such as chlorine treatment of cut vegetables, and CO treatment of meat). ‘Food safe’ products are regulated based on their expected risk to humans (not fish, not amphibians, not reptiles) when used in the expected food-exposure way (which is different than living in contact with it 24/7, which would be the case for many products for many herps and aquatics). Supposing that ‘food safe’ means ‘safe for animal care uses’ isn’t accurate.

[caryl]

@socraticmonologue

The connection between ‘food safe’ and safety for animal use isn’t that direct, and there are some easy counterexamples (such as copper cookware, which would kill marine inverts kept in it; also chemical treatments of certain foods that would kill a range of animals, such as chlorine treatment of cut vegetables, and CO treatment of meat). ‘Food safe’ products are regulated based on their expected risk to humans (not fish, not amphibians, not reptiles) when used in the expected food-exposure way (which is different than living in contact with it 24/7, which would be the case for many products for many herps and aquatics). Supposing that ‘food safe’ means ‘safe for animal care uses’ isn’t accurate.

You’re quite correct. Thanks for adding that additional clarification. I am well aware that many substances which are safe for humans are wrote dangerous for other creatures and vice versa. I did not mean to imply otherwise. I was referring solely to silicone sealants, which was what I had been discussing, but I did say “the product.” I did not at all intend that to refer to anything else.

[socraticmonologue]

Yes, it looked like you were simply referring to silicone sealants. My point was that a silicone adhesive that is food safe is not thereby “also aquarium and vivarium safe”. I simply zoomed out to the general considerations that make that association (food safe silicone adhesive = animal safe silicone adhesive) false – that way the point was made about the particular topic at hand, and the overarching explanation can be used in future cases that involve something other than adhesives.

Here’s an example of a food safe silicone adhesive is not aquarium and vivarium safe, just to illustrate.

[mcdean1047]

I just sealed my uromastyx’s new enclosure with silicone 2 before realizing the difference and it has now cured. Do I need to remove it and get something else to seal it with? I sealed it for the sole purpose of putting in play sand.