Pre-sale Home Improvement: Kitchen floor re-grout

Hubby decided to re-grout the kitchen floor before we hold the open house to find our buyer. There were holes in the poor grouting job done for the previous owners.

Here's how we did it:

1) He gets out his handy-dandy DeWalt Oscillating tool:

2) He gets a blade for the oscillating tool for removing the grout. The DeWalt blade had a rivet which is where the blade separated. This rockwell one worked much better.

3) He got some help from the house painter who also does some odd jobs for us when there aren't enough painting jobs around. They removed the grout easily from almost the entire kitchen.
4) *I* got to then clean the entire house because there was a fine dust on EVERYTHING!!!
5) He then did 4 batches of grout and made the floor look gorgeous!!!!

It's so beautiful and the grout job is so clean and no more gaps! I absolutely love it!

Next job for the floors is to clean the grout lines under the dining table, entry way, & bathroom also. I'm going to try method #4 from the following link:
https://brendid.com/ultimate-guide-to-cleaning-grout-and-tile/

Any grouting experiences you have had?