Thread: Silicone - chemical removal

A short report on my recent attempts to lift cured silicone from a fibreglass panel on a boat. The panel is interior and does not have a smooth, flat surface. The silicone was spread over about one square foot and the panel isn't very thick, maybe 2-3mm.

I attach a photo showing some of the shavings of silicone that I removed by using a blade. These shavings are about 1 to 2mm thick.

Of course, the problem is, after removing these shavings, there is still a thin layer of silicone left that is sticking to the fibreglass like cow s... to a wool blanket.

I am aware of advice along the lines that if I were to use sanding or abrading to get this final layer off, it would just cut microscopic grooves in which silicone particles would be embedded untill the end of time. And the surface not being smooth makes scraping tough.

So I thought the answer must be "chemical" removal. So I bought two products (here in Australia) from hardware suppliers (shown in photos):

1) Selleys Silicone Remover (diluted sulphuric acid in a gel form)
2) Mötsenböcker’s Lift Off® Silicone and Acrylic Caulk and Foam Sealant Remover

Results after application as per instruction:

1) Selleys: Left for 24h; seemed to convert a bit (possibly 20%) from the thickness of the shaving leaving crumbly bits that could be wiped off. But the rest of the 2mm shaving is pretty much intact and tough as before.

2) Mötsenböcker’s: No effect on the shaving at all.

Pretty disappointing results.

Should mention that I have tried the usual stuff: Acetone, Mineral turps, Petrol. In respect of these, it sounds like Xylene would be the superior option in this class. I quote from a web site:
"Soaking in solvents, such as xylene, has been used to swell and soften the silicone to allow removal by mechanical tools. This method risks damaging the substrates and assembled package, due to the intricate and compact nature of microelectronic assemblies. It also may fail to remove any remaining silicone residues on substrate surfaces."

However, ideally, I am looking for a "silicone digester" - ie. something that "CONVERTS" cured silicone to a soft cream.

So went to do a web search for products available anywhere. The following consumer reviews in Amazon caught my eye:

- " After a few hours I came back and wow the Mckanica just melted the silicone. You could literally wipe the silicone away with a cloth with no silicone left behind. The Mckanica also did not affect the paint on the metal flashing"

- "It was safe on my shower stall, tub and granite sink. I left it on for 3 hours and every bit of silicone caulk was melted- Amazing.... "

Seeing phrases like "could wipe the silicone away with a cloth" and "melted" makes me deeply envious. But after my experiment with Selleys, I find it hard to believe. One thing to listen to Amazon users, but probably much tougher to hear the cold scepticism of boat builders.

So, has anyone tried the McKanica miracle gel, or know of purely chemical methods of "converting" cured silicone to a paste?