Just to add that I've used this recently on a few jobs.
Monday I used it on some tumbled riven chinese slate. For a test I had applied 6 lots of Fila slate sealer to one splashback, and just the BAL temp' sealer to the other splashback.
The second splashback was a late additional afterthought from the customer and so I didn't have time to seal it umpteen times. I explained that I would grout it but he would need to seal it properly later.
I grouted them together, with brown grout. (sorry it was Mapei Chocolate! - Customer's choice)
Surprisingly the temporary sealer did a better job than the Fila. There was no struggle to wipe away dried residue from the nooks and crannies.

You might think why use a temporary sealer? But for this instance it was perfect.

I also used it late one night to protect £4k worth of Botticcino marble I had just finished fixing. I was leaving it for the weekend and I suspected that the builders would walk all over it.
It took around 10 mins to wipe a good single coating on (BAL recommend two coats but I couldn't wait 15 minutes for the 1st to dry - it was Friday and I was thirsty!).
I returned Monday and it was covered in mud. Had I not used temp sealer, it would have been a massive clean-up job.
As it was, a quick wipe over with the washboy and I was ready to grout.

A good product and worth carrying in the van.

I found a new application for this yesterday.
Was tiling a connie floor up to some very rough and porous brick work. No skirts to go on.
I sealed the bricks round the floor edge 3 times with the sealer, it didn't change the appearance of the brick, but it did stop me staining them with sandstone grout.
Worked like a charm.
The bricks were so rough I couldn't mask them, and I couldn't use silicone either.
(Was a small solid floor so I opted for no perimeter expansion)

Good one Mark....another class example of a product being used in the right situation...