My first thought is that if you squeegee the shower, that's good enough. What are you hoping the vinegar/lemon spray will do?

The general idea of cleaning products is that you apply something to a soiled surface for the purpose of loosening the dirt and then wipe or rinse off the soil and cleaning substance. In your case, you are spraying an acid on your shower - but to what end?

@graywings: thanks for your feedback. My goal with the vinegar is to provide an inexpensive but effective natural way to keep mold & mildew off my show walls & enclosure.

It obviously works as my shower has been extraordinarily clean ever since we started using this process.

However, I've read contradicting articles & opinions on line as to what the acidic nature of vinegar will do to the tiles & grout.

I use straight vinegar too in my shower and I've never had a problem with it doing any damage. It is good against mould

What has worked well for me for over 20 years is to squeegee the shower and let a fan blow into the shower. I leave the fan on all night after showers.

There will be no mold in a dry shower and no possible damage of an acid gradually eating into the tile or grout surface.

http://www.flceramic.com/en/faq.html

Good info.