The Medway Handyman wrote:
I re-seal a lot of baths, popular job. Key to doing it properly is
getting all the old silicone out & starting on a clean surface.

Bath I did today had a rigid plastic trim around it which had to come
off prior to re-seal. Under this in areas which could trap water,
the silicone seemed to have degraded badly.

Consistency of cottage cheese! Never seen anything like it before. Does
silicone degrade if kept permanently wet?

Yes, I have come across this. I struggled to think where and when but I
think I was the cause of it Whilst an impecunious post grad student in the
early 70s, my wife and I bought an end terrace house that required a lot of
work - hence how we could get on the property ladder. The kitchen had to be
stripped and the bathroom tarted up. I sealed the fittings with some cheap
silicone bought from a high street store that still exists, (I'm pleased I
Googled before I mentioned it).

We were only in the house for about five years and I had to replace the
cottage cheese several times.

Moving to a brand new house, after a few months, I had minor issues to fix
such as a loose hand basin in the downstairs loo and sealant coming away
round the bathroom handbasin. Fortunately, I still had the residue of this
tube of sealant. Fool!

Had to be replaced smartish.

Bought some proper sealant and no problem.

Never bought cheap sealant since.