New Floor: how smooth is ideal to prep for epoxy?

[ersatzs2]

Thanks for the earlier advice on making my new concrete floor level vs. pitched. Follow up question: how smooth should I have them finish the surface? My inclination is that the smoother it is, the more durable the finish will be since it will be a more uniform coating thickness. On the other hand, 'smoother' costs extra so if it is unnecessary or worse, undesirable, it would be nice to know...

 

[twostory]

I had a power "steel trowel" finish. It is very smooth and does not cost extra. I have read that I will actually have to rough it up before I epoxy the concrete. I figure a good acid etch will do the job. It will be next summer before I epoxy the floor, so for now I have a nice smooth bare concrete floor.

You do not want a "bull float" finish, that would be too rough, same with a broom finish, that is what an outside sidewalk gets.

 

[rizzorace]

After doing my floor ultra smooth with a power trowel in preparation for epoxy I wound up having to rent a scarifier to make the surface of the concrete rough so the epoxy has something to bite into. I used benjamin moore M40 and M41 industrial epoxy. My floor has 1 coat of the sealer and 3 coats of the epoxy, each sanded in between coats, it reflects the ceiling like a mirror!

 

[twostory]

After doing my floor ultra smooth with a power trowel in preparation for epoxy I wound up having to rent a scarifier to make the surface of the concrete rough so the epoxy has something to bite into.

Nice looking floor.

My question, would an acid etch rough the floor up enough? Maybe a few acid etchings?

Did the scarifier rough the floor up too much? I think the epoxy producers want a 120 grit surface. How rough was your slab after the scarifier?

Thanks in advance.

 

[Winmon]

You do not want the floor smooth for epoxy. Alot of guys will use a Edco Grinder/Surfacer or ShotBlast it. Most companies that do epoxy floors will Shotblast it first. As far as the muratic acid goes, if you mix the it right (i.e. strong enough), you will just have to do the muratic acid wash once. Be sure to rinse very throughly!