# Silicone Fumes?



## DJboston (Oct 25, 2008)

Anyone have any problems with silicone fumes? In the past, I never really thought about it too much as usually a couple days after using silicone I don't notice a smell.

Recently, I haven't changed a thing but I've been smelling fumes and I can't understand why. This is WAY after the silicone cures. 

I'm using GE silicone 1. Brand new bottles. I have used a few different bottles bought from different places. 

Using the silicone to make conversions to 20 gallon extra tall tanks. 

It's not the the silicone isn't curing. It is totally cured. 48 hours later the fumes are still bad. Just really annoying and I can't do anything with the tanks if I'm smelling intense silicone. I'd like to get these tanks done so any suggestions? I'm going to give them a good cleaning with diluted dish soap in water and see if it helps.

Thanks
Dan


----------



## Nightstalker (Mar 30, 2010)

I can not say that I have had that problem. Like you said, usually within a day or two it is all gone. And is it the GE II silicone? How thick is the layer of silicone that you laid down?


----------



## Frogman8 (Sep 28, 2010)

It took the fumes in my tank approximatly 1 month to go away. Did you try leaving it outside in a garage or shed for a few days, that may speed up the process!


----------



## Pumilo (Sep 4, 2010)

Pumilo said:


> Without knowing complete information here, I'm going to hazard a guess agreeing with Dave. I think it may have been a curing issue. Some brands will cure faster than others. Under the best of conditions, Silicone takes 24 hours to cure nad this refers to a 1/8" bead. Personally, I try to give any silicone twice the cure time the manufacturer recommends as there are various things that may affect curing time. Things that will affect curing time are; temperature, humidity, thickness of the bead, age of product, and containment. At least some brands will lose stability with repeated freeze cycles during storage. Containment would refer to air being able to circulate around the silicone. According to Boss brand silicone, curing time generally refers to a bead 1/8" thick with no containment. A half inch bead may take up to 72 hours to cure. A thick bead with full containment may never cure.
> *So if we are sealing the inside of a viv, it is important to leave the lid off. Even so, you have partial containment as the sides will be blocking airflow. A small fan to circulate the air will help this.* One thing to remember is that if there is ANY SMELL AT ALL, then the product is NOT fully cured...BUT not being able to smell it, does NOT necessarily mean it is fully cured. A thicker bead could still be curing deep inside, but the smell is "sealed off".
> I'm a window repairman and I use an estimated 100 tubes of Silicone per year, for the last 20+ years. I have tried to use old tubes that remained tacky fully two weeks after application. At that point I assumed project would never cure and it was disassembled and redone with fresh silicone.
> 
> ...


Some thoughts for you from another thread. As far as waiting two weeks, that is really for completely filled aquariums. If smell is gone, you are good to go. I do recommend GE silicone 1 after studying this thread. http://www.dendroboard.com/forum/parts-construction/35720-bio-seal.html


----------



## DJboston (Oct 25, 2008)

I thought air doesn't make a difference. Silicone is a chemical cure. I've made silicone molds for years but the molding silicone has no smell to it even when curing. Not to mention it's two parts and I never understood what tells the silicone to begin curing once it leaves the bottle with the silicone we use.

Usually silicone is 2 parts though the window and sealant silicone is always 1 part.

I'm just going to let them air out and not touch them for a couple weeks. 

D


----------



## DJboston (Oct 25, 2008)

By the way, I've been using this silicone for 13 years alone with dart frog tanks...It's something I never had to put as much thought into. I'm going to put some computer fans inside the tanks.

D


----------



## earthfrog (May 18, 2008)

Part of the issue is condensation from the outside air---given nighttime temperature drops, the moisture tends to settle inside the tank overnight, which will prolong curing in a small enclosed environment with little air exchange. This is part of why it cures faster when applied to other more ventilated surfaces as contrasted with inside a compartment.

If you are still smelling acetic acid, it is still completing the curing process. 'Hard to the touch' isn't always fully cured. 
For example, I recently applied shellac to a table surface. While it was hard to the touch within a day, it still is not fully cured for several months afterwards even though there is no smell. 
Silicone cures faster of course, and letting the smell dissipate completely is a safe way to do it IMO.


----------



## DJboston (Oct 25, 2008)

I agree. Once I can't smell it, I feel safe enough.

D


----------



## Steve88W (Jan 21, 2011)

Yup, my tank still smells and it has been curing for 2 weeks. I gave mine a couple of gentle rinses and let it dry in the garage. I read somewhere that adding plants after a week or so helps eliminate the remaining smell. If in doubt rinse, dry, and let it air out. 
Has anyone tried to place a box of baking soda in a bowl inside the tank to help absorb fumes?


----------



## DJboston (Oct 25, 2008)

I wonder how much of lingering smell is actually "fumes" anyway. Fumes take a while to build up and smells don't.

I once coated a foam background I sculpted. Just brushed the silicone on. After it was cured I shoved it in the tank and never thought twice about smelling it. The pair of frogs it was in with just gave me 13 eggs in 5 days...

I wouldn't think it would have much more curing to do after 2 weeks. Just a matter of getting the smell gone.

D


----------



## Pumilo (Sep 4, 2010)

DJboston said:


> I thought air doesn't make a difference. Silicone is a chemical cure. I've made silicone molds for years but the molding silicone has no smell to it even when curing. Not to mention it's two parts and I never understood what tells the silicone to begin curing once it leaves the bottle with the silicone we use.
> 
> Usually silicone is 2 parts though the window and sealant silicone is always 1 part.
> 
> ...


My information came direct from from Boss brand silicone manufacturer. Besides, think about it. If exposure to air did not matter, it would already be hardened and fully cured in the tube, long before you ever got it! It may be a chemical cure, but as you pointed out, silicone sealant is a one part tube. The only change that triggers the cure, is exposure to air.


----------



## DJboston (Oct 25, 2008)

You're right. So that must be the difference then. Ever since I put a fan on the new tanks, I've been smelling the fumes less and less and I've been turning off the fan to see if fumes build up and I can barely smell anything. So it does seem to be working.
D


----------



## Ed (Sep 19, 2004)

DJboston said:


> I wonder how much of lingering smell is actually "fumes" anyway. Fumes take a while to build up and smells don't.
> 
> I once coated a foam background I sculpted. Just brushed the silicone on. After it was cured I shoved it in the tank and never thought twice about smelling it. The pair of frogs it was in with just gave me 13 eggs in 5 days...
> 
> ...


With the silicone used in the enclosures, curing results in the formation of acetic acid, which then has to outgas from the silcone product. In a closed space (like the inside of an enclosure) the fumes, build-up (which is typical of outgassing) and depending on how thick the silicone is laid onto the surface changes how long it takes to outgas and to fully cure. 

Depending on the actual product used silcone can either be a one product system or a two product system. Systems that don't smell and require exposure to moisture are typically the result of a formulation that includes organotins and results in the outgassing of ammonia, other formulas can use a titanium epoxide. 

If I remember correctly, the curing of the silcone typically used in the hobby is the result of exposure to atmospheric moisture. 

Ed


----------



## DJboston (Oct 25, 2008)

Oh interesting! I can always count on Ed for weird info no one else would know! haha

Seriously though, a lot of the molding silicones were in fact tin based as you mentioned and were two parts. I also experimented with platinum based silicones as they're cutting edge for replicating human skin for prosthetic use.

Didn't know moisture in the atmosphere mattered so that's good to know. So I assume the fan is just moving along built up fumes faster.


----------

