A couple of people looked at me in absolute astonishment at the idea that I could possibly not have known sealant was applied using a sealant gun.

You can buy sealant in a squeezy-tube rather than an inna-gun tube. I did the sealant round our bath, the sticking-on of tiles, and the grouting between said tiles, all done 'by hand' with squeezy-tubes. It's like piping icing on a cake!