another layer of silicone

[dvs]

I have been trying to reseal a 125 gallon tank and had to restart once already. The first attempt did not look good at all and I didn't even test it. I just redid the silicone and I am hoping that the tank will hold water. It looks like it will, but I would like to add more silicone in some of the spots that are either light or have shelving from where the tape was removed and the silicone wasn't tapered enough. I had a lot of trouble with the silicone drying so fast and was working on it alone. One spot got messed up by the tape when I pulled it and I added a new layer over the half set mess.

Can I clean this job up with another layer of silicone to smooth out some of these spots or is that a bad idea? Like I said I think it will hold water, but I am worried about the durability of a couple spots. I would also like to smooth out the rough spots if possible.

 

[jcardona1]

silicone will not stick to silicone. your best option would be to remove the bead in question and redo the section

 

[CHOMPERS]

^^^ Unfortunately this is repeated often and not tested.


The fact is that new silicone will bond seamlessly to clean cured silicone. This information came from a Dow chemist, and I have since tried it. It bonded to the cured silicone.


New silicone will not bond to dirty silicone. A thin film of organics between the layers is enough to prevent bonding.

 

[dvs]

How would that work if silicone won't stick to itself? Doesn't it have to be one continuous seal?

 

[carcrazy]

I have sealed a used 10 year old 25g tank that sprang a leak by cleaning the old silicone and applying new silicone over top of it. That was 15 years ago and it hasn't leaked since. (Just watch, it'll probably start leaking now because I'm talking about it).

 

[dvs]

^^^ Unfortunately this is repeated often and not tested.


The fact is that new silicone will bond seamlessly to clean cured silicone. This information came from a Dow chemist, and I have since tried it. It bonded to the cured silicone.


New silicone will not bond to dirty silicone. A thin film of organics between the layers is enough to prevent bonding.

Great thanks for your response! I will add another layer over the sloppy sections tonight and let it cure until Tuesday or so. Hopefully it will be looking good and holding water. My fish are ready for the big move for sure!