There is a lot of debate about the safety of silicone caulking. But most professional mermaids today agree that it's not safe and shouldn't be used for tails.
Why isn't it safe and How do we know it's not safe ?
Fun fact: If a food contains less than 1g of sugar per serving size it can be marked as 0 sugar. Companies will change the serving size to be smaller to mark the box zero sugar. It contains some sugar but not enough to count. But what happens if you eat an entire box? Those little bits add up.
It makes sense that the same rule applies to other things right? So let’s say small amounts of toxins are allowed in a product meant for industrial use. That small amount adds up the more you use. Making a tail from tubes of silicone caulking can take over a dozen tubes!
If something is technically safe to be used a certain way. Nobody knows the effects it could have by using it a different way and it's only tested for quality and safety for its specific use. If it’s “safe” in small amounts, who knows how dangerous it could be in large amounts when all those micro measurements of allowed toxins add up.
So what does that have to do with mermaids tails? Caulk!
Silicone caulk is made to be used for sealing sinks, tubs, aquariums, other household appliances and spaces. It’s available at the hardware store and can be very dangerous when uncured. When cured it’s only tested for things like accidental food contact or long term mold resistance. So why do some people think it’s a good idea to take a somewhat toxic material made for sinks and smear multiple tubes of it on themselves to make mermaid tails? I honestly don’t know. Here’s what I do know:
Things meant for consumption have high standards and regulations because it’s a safety issue. Things meant for construction are just marked as dangerous they don’t do any experiments to see how it will effect people long term Because why waste money testing things for skin contact and long term exposure when it’s not meant for things like that in the first place?
Some caulkings are marked “meets standard for accidental food contact” this means, if it’s on your sink (where it’s supposed to be used) and you accidentally drop food on it then quickly scoop it up and eat it. You will be fine. It meets the absolute minimum to be considered safe but only a one time accidental contact.
Some caulks are marked aquarium safe. There is a big misconception that aquarium safe and skin safe are the same thing. When used on an aquarium and allowed to properly cure it is safe for fish.
it is important to remember that aquarium safe does not mean skin safe. Aquarium safe means if cured properly it's ok in small amounts to secure a fish tank together, that is far from smearing a gallon of it on fabric and wearing it as a tail.
It hasn’t been tested for repeated skin exposure. It’s not tested for stretching, will stretching it over and over cause it to break down and perhaps release some toxins? We don’t know it hasn’t been tested for that because it’s not supposed to be used that way!
It is always important to read the MSDS which is the material safety data sheet: this is the safety information that comes straight from the manufacturer. This is referred to in the event of an emergency. It tells the risks, results of experiments on lab animals, emergency procedures, and toxic ingredients that are or may be included.
Basically because it is not made for skin (it's made for construction and plumbing) there is a chance that the toxins are in it. It is not regulated as something meant to be put on skin repeatedly, so legally it can contain these toxins.
Silicone caulking is an RTV silicone or Tin cure meaning it cures on its own at room temperature. Platinum cure silicone has 2 parts that need to be mixed at a certain ratio in order to cure but Tin cure does not.
The industry standard for skin safe silicone is dragonskin it's a medical grade platinum cure silicone that is certified skin safe.
here's what they have to say about Tin cure silicones and skin safety:
sometimes it doesn't cure all the way through but you think it has. If you swim and it is not cured all the way, the uncured silicone will wash off and you will be swimming in water full of toxins from the uncured silicone. this is dangerous.
There are different types of silicone and while they are all regulated somehow, they are only approved for the recommended uses of that product. So caulk isn't made for or recommend for or approved for use on skin or use for tails.
Some caulk says it meets the standards for accidental food contact. This means if you seal your sink with it, and you are cooking and the food accidentally touches it, you are ok. This does not mean it is food safe. Be careful with wording and make sure to carefully read all labels and the MSDS.
Are any caulkings safe for tails?
There is 1 specific type of caulk that is generally accepted by the mermaid community as well as a few tailmakers as safe for tail purposes in very small amounts. GE silicone 1 (not 2!) clear, is generally ok in small amounts like a small tear repair, but is still caulk so make sure it is 100% cured before you put it in the water and don't use in a place where it is in direct contact with skin. Entire tails made of caulk are a generally a huge no no. Honestly silpoxy silicone adhesive is the best for tail repairs and fin attachments. It's safe and it works better so just use that.
While it's true that there have been no reported problems with one particular type of silicone caulking used on tails (there is still a risk. There are many unknowns about long-term skin contact repeatedly because it's not made for skin.
Long-term effects might not become apparent for many years you might not even make the connection between your health problem and the tail you used years ago.
More issues with caulking for tails (as if there weren't enough already)
Another problem is that some caulks are very toxic (like Alex plus) and young or inexperienced Mers trying to create their first tail on a budget based on caulk tails they have seen, might not understand that there are different types of caulk and this is potentially dangerous.
why risk it?!
Why would you risk things like blood poisoning, cancer, and killing animals you are swimming with? To save money? you won’t even save much because caulk tails don’t stretch and don’t last so you will have to pay to make a new tail soon anyway.
Tail-makers have been experimenting with different types of silicones for years and have determined dragonskin to be the best. It’s safe and it’s long lasting and stretchy. If something else worked just as well and was cheaper, we wouldn’t be paying $250 a gallon for dragonskin.
Why would you risk possible health issues for a tail that won't last, looks sloppier and less realistic than a dragonskin tail, and doesn't stretch?
Conclusion
Just do everyone a favor, including yourself, and if you want to silicone tail, get one made of certified skin safe materials like dragon skin.
Caulking stinks (really it smells awful) only use it in small amounts for tail repairs or fin attachments where you won't touch it over and over, use GE silicone 1 clear or silpoxy and wear gloves and a mask.