I have been following most of these threads on re-bedding of fixed port lights with great interest. I have read about, and experienced, the difficulty of removing port lights bedded with various modern squeeze-tube caulks. And I know that butyl tape, while great for bedding things bolted down, is not ideal for something as delicate as our fixed port lights. I can now share my limited experience in using an old-school product called Dolfinite for fixed port lights.
When I got my 1987 32-3 in spring of 2021, there was obvious rot at the aft corner of the aft-most port fixed light over the nav station. I
posted about that issue nearly 2 years ago. Soon after that post, I removed that port light, cleaned it up, and rebedded it with
Dolfinite. Dolfinite bedding compound has been around for a long time. It sells for around $80 for a quart, not much less by volume that 3M 4200, but it never goes off like an open tube of modern caulks, and it never hardens. And it is very easy to work with.
Two years after using Dolfinite on that one port light, with no signs of leaking, it was time to remove the other three fixed port lights for eventual rebedding. Aided by Anti-Bond, as recommended by Christian Williams, it took a total of about 4-1/2 hours to remove them (90 minutes each!). In contrast, I was able to remove the Dolfinite-bedded leak-free fourth port light in only
eleven minutes.
When I eventually re-install the fixed port lights, they will be bedded with Dolfinite.
I have noticed, from my own port lights, and photos of others' here, that typically great massive gobs of "adhesive sealant" materials are commonly used for bedding these port lights. But it occurs to me that there is little need for "adhesive" for our port lights, but only for "sealing", and no need at all for "filling", which is all that most of that stuff is doing.
Dolfinite spreads with the consistency of thin peanut butter, so it is easy to apply. Cleanup is easy, and can be expedited with mineral spirits. The manufacturer claims that it never hardens, but instead it can dry or cure to something like a stiff wax. When I re-bedded my port aft port light, I applied the Dolfinite to the aluminum flange only, where it comes in close contact with the fiberglass hull. There is no value in material placed between the port light frame and the hull material, except at the outboard surface. After installation of the interior trim for the port light, a cloth soaked with mineral spirits can easily remove any Dolfinite which oozes out from between the frame and the hull.
After struggling to remove the port lights, with concerns about breaking the glass, damaging the hull, warping the frame, and even whether successful removal is possible, the ease of using Dolfinite bedding compound looks really appealing.
Port light removed after two leak-free years after bedding with Dolfinite. Elapsed time for removal: 11 minutes.
Dolfinite bedding compound after 2 years. It resembles a stiff wax.
Waiting for the Anti-Bond to break down the caulking. Lots of wedges in use in hopes of breaking the bond.
Ninety minutes of struggle, using Anti-Bond, the fixed port light finally lets go.