Having used both SIG model airplane dope and super glue, my preference is super glue. As Lloyd mentioned, not all of the model airplane dope is fully “fuel proof”. The SIG brand is good but getting hard to find and is pricey. Once opened, the remainder tends to harden in the bottle and ends up being wasted.
The “Original Super Glue” comes in tiny twin packages at the local dollar store. You can coat any float for around 50 cents or less. There is virtually no waste, and it works. I had a float in a pressure tank immersed in fuel mix for a couple of months and when I took it apart the super glue finish showed no degradation. 2-3 light coats with a disposable brush works well.
It is very important to give whatever sealant used plenty of time to cure before exposure to the harsh effects of gasoline. Some expose the coated float to gas the next day after coating it, then complain that the sealant is no good. A week or more to cure is much better.
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