I am having my floors sanded and refinished with a water-based poly mix call Mega (commercial grade). They are not staining, just finishing. They said they would seal it and put 3 poly coats (water based) on and do it in one day. I asked if they could do it in two and they said no. They said they only need 45 minutes of dry time because it's water based. The price is really really good so I want to believe this guy but some of the other quotes were saying 2 and 3 days. Im a little nervous about this.

There are some waterbased formulas, that do dry fast. The cost of the product is pricey, but production time makes up for it.

OMU, will take days.

dmuse, We have been using Mega for a long time and it's great.
"They said they would seal it and put 3 poly coats(water based)on and do it in one day".
I would call that 4 coats and we would do it in 2 days. It tells you on the Mega container to allow the first coat to dry 2-3 hours but I guess they will be using Bonaseal for the sealer and it will dry very fast.
We use a moisture meter to determine if the finish is dry enough for another coat. We have used many types of water finish and in our climate(Mississippi Gulfcoast) we can only get 2-coats per day. We could put all 4 coats on in a day but if enough dry time is not allowed between coats the finish will never harden properly and will scuff and scratch more than normal.
If you are in a very dry climate it may work. I hope they use a moisture meter to know for sure.
Buddy

Only way to get 4 coats in one day is to use laquer or real thin coats and high speed fans and heaters. Neither way is good.

dmuse,

Even here in dry Wyoming it is hard to apply 4 coats i one day. You do need a moisture meter to do it just like Buddy said.

Maybe they can sand and seal the first day, then get down three coats. Start early, stay late, dry climate this seems do able. Zinnzer Seal coat is the bomb, but all 4 in a day is really pushing it, I agree. If you can stay on top of it, use a moisture meter, 3 is possible under good conditions.