refinish shellac floor to polly

First if the floor is in good shape, I would specify that they not use a drum sander on it. If it is just a worn finis, then a cleaning with alcohol is all that is needed. That will remove the old wax and most of the shellac and anything remaining will act as a sealer.

How would one go about using the alcohol and what type to purchase? denatured at home depot?

About 6-8 months prior to pulling rugs I spilled a large bottle of alcohol on rug so when I pulled rug I noted a irregular circle on floor of mostly removed shellac and that the floor shade was much lighter so the alcohol also reduced the stain.

After using alcohol can I just buff with brush pad and then start with rag to put down water based urathan And repeat brush and rag second cote then rag down third coat 24 hours later?

Yep, that's the stuff.

That all depends on the specific situation - condition of the floor. Sometimes you get lucky and sometimes not. It is not unusual to find some damaged or uneven areas. If after cleaning up with the alcohol it looks and feels even and good, then you should be ready to go. I would expect a little buffing as you suggest would be a good idea.

In removing the shallac do I just brush it on and then off sponge off the residue till the floor is clean? Stan

I am guessing it is more a matter of finish than a residue. Depending on what you now have, you might want to do some light sanding and then refinish. Does it feel smooth?

First try a small hidden area and try just using a little finish and see what the results look like.