There are several products that can be used to fill the hole, which can then can be re-polished to blend in with the existing floor. We do our best to create simulation, however, this will be a patch and it may still be noticeable in the finished floor.
All spills should be cleaned as soon as possible. Our polished concrete floors are coated with a stain resist product which helps protect against water and oil based stains. Though an exception for staining will include a material, especially acid based and left on for a long period of time, making the polished concrete vulnerable to marking.
The process is not dust-free, however, the machines are connected to vacuums that greatly reduce air particles. Sometimes we may need to wet polish to expose more aggregate, this process will produce a wet slurry that we work to great lengths to contain for our disposal.