resetting a sink on a fiberglass countertop

[Steve Hague]

Our 1978 Trillium 4500 developed a water leak into the cabinet below the sink on our last outing. The primary source of the leak was worn O-rings around the hand pump, which was a simple replacement of the two O-rings.
The secondary, and more problematic problem was that water was flowing under the rim of the stainless sink and into the molded fiberglass cabinet below. When I pulled the sink I was surprised that there was no sealant putty or tape between the sink rim and the fiberglass countertop. The 3/4 inch plywood underlying the fiberglass countertop had minimal water damage, but had sagged about 1/4 inch across the back span of the cutout, so I fashioned a support to bring it up level.
Questions:
Has anyone else seen this lack of setting seal when pulling their sink from a molded fiberglass cabinet?
When I reset the sink, what should I use to reseal the sink? I have butyl tape, so I'm tempted to use as I already have it and its flexibility, adhesiveness, and resistance to drying seem to be advantageous.

[jon carpenter]

We have owned 2 Casita SD's with water leaking around the sink lip down into the cabinet below. Upon closer examination, neither one had any sealant nor gaskets around the lip. One didn't even have the screw clips on the underside of the sink and was only held in place by the plastic drain p-trap. I used the grey plumbers putty and new screw clips for correctly mounting the sink. Did NOT used silicone.....just the plumbers putty. There are a couple thoughts on this as to whether the putty will eventually stain the fiberglass but after 6 years on the first one there was no sign of any staining.


Others may chime in with other ideas or opinions.


good luck

[Alex Adams]

I second plumber's putty. I have removed sinks that had been in place for 75 years where the plumber's putty was still pliant and forming a seal.

[Steve Hague]

I appreciate the replies. Plumber's putty it is unless I hear a convincing case to the contrary.
Thanks
Steve

[ordjen]

Originally Posted by Alex Adams

I second plumber's putty. I have removed sinks that had been in place for 75 years where the plumber's putty was still pliant and forming a seal.

I would avoid regular plumbers putty. There is a special plumbers putty made for synthetic sink materials. The oils in conventional putty will leech into the plastic material and stain it yellow. I have observed this many times around the sink drain plug where regular putty was used on plastic composite sinks.

[CharlesinGA]

In a pinch I would think that Butyl tape like is used on the outside under fan installations and the like would also work. But Plumbers putty applied liberally and the excess removed would be the preferred method.

Charles